SecProbe.io

December 1, 2025
Lynne Fitzpatrick
President & Chief Financial Officer
CME GROUP INC.
20 South Wacker Drive
Chicago, Illinois 60606
Re:CME GROUP INC.
Form 10-K for Fiscal Year Ended December 31, 2024
File No. 001-31553
Dear Lynne Fitzpatrick:
            We have completed our review of your filing. We remind you that the company and
its management are responsible for the accuracy and adequacy of their disclosures,
notwithstanding any review, comments, action or absence of action by the staff.
Sincerely,
Division of Corporation Finance
Office of Crypto Assets
cc:Jonathan Marcus

CORRESP
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September 25, 2025

U.S. Securities and Exchange Commission

Division of Corporation Finance

Office of Crypto Assets

100 F Street, N.E.

Washington, DC 20549

ATTN: David Irving

    Mark Brunhofer

Filed Via EDGAR as Correspondence

    RE:     CME Group, Inc.

        Form 10-K for Fiscal Year Ended December 31, 2024

        Form 8-K Filed July 23, 2025

        File No. 001-31553

Dear David Irving and Mark Brunhofer:

This letter sets forth the responses of CME Group, Inc. (“CME”, “the Company”, “we”, “our” or “us”) to the comments of the Staff of the U.S. Securities and Exchange Commission (the “Staff”) from comment letter dated September 12, 2025 with respect to the above referenced Form 10-K and Form 8-K. For your convenience, we have duplicated the original comments of the Staff as set forth in the comment letter below in italics in providing our responses to each of the Staff’s comments.

Form 10-K for Fiscal Year Ended December 31, 2024

Notes to Consolidated Financial Statements

Note 18. Segment Reporting, page 82

1.Please represent to us that you will revise future filings to include the geographic disclosures under ASC 280-10-50-41. Otherwise, tell us why they are not required.

1

CME Response:

We will provide the geographic disclosures in our future annual filings, as required by ASC 280-10-50-41. The following is an illustration of the proposed disclosure to be included within footnote 18, Segment Reporting, in our Form 10-K.

Material revenue and long-lived assets are defined as those which represent 10% or more of total revenues and long lived assets. Revenue and long lived assets by country for the years ended December 31, 2025, 2024 and 2023 and as of December 31, 2025 and 2024 are set forth in the table below:

  Revenues (b)

  Long-lived Assets (c)

(in millions)  2025  2024  2023  2025  2024

United States $ xxx $ xxx $ xxx $ xxx $ xxx

United Kingdom (a)

  xxx  xxx  xxx  xxx  xxx

Other foreign countries  xxx  xxx  xxx  xxx  xxx

Totals $ xxx $ xxx $ xxx $ xxx $ xxx

(a) United Kingdom includes Great Britain and Northern Ireland.

(b)  Revenues are classified based upon the location of the customer.

(c)  Long-lived assets represent property, plant and equipment, indefinite-lived intangible assets, amortizable intangible assets, and other investments included in other assets. See Note 5 for further information on property. See Note 6 for further information on goodwill and other intangible assets. See Note 17 for further information on investments included in other assets. These assets are reported in the country where they are primarily used.

2.You reference Adjusted Operating Income and state that you recorded all-time record Adjusted Operating Income in the second quarter of 2025. We note that you do not quantify Adjusted Operating Income or include a reconciliation from a GAAP measure to this non-GAAP measure. Please either remove reference to this non-GAAP measure in future releases furnished on Forms 8-K, or advise otherwise as to why it is a meaningful and useful measure and include all of the disclosure requirements of Item 10(e) of Regulation S-K.

CME Response:

In future filings, the Company will include all applicable disclosure requirements of Item 10(e) of Regulation S-K for non-GAAP measures used. We believe that the presentation of non-GAAP Operating Income provides important supplemental information to management and investors about financial and business trends relating to the company’s financial condition and results of operations. We propose to include the following table within our future releases on Form 8-K to quantify and provide a reconciliation for GAAP to non-GAAP Operating Income.

2

CME Group Inc. and Subsidiaries

Adjusted Revenue, Operating Expense and Operating Income Reconciliation

(dollars in millions, except per share amounts; shares in thousands)

  Quarter Ended

September 30,

  Nine Months Ended

September 30,

  2025  2024  2025  2024

Total Revenues  $     XXX

 $     XXX

 $     XXX

 $     XXX

         Real estate-related costs (credits)             XXX

  XXX

  XXX

  XXX

Adjusted Revenues $          XXX

 $          XXX

 $          XXX

 $          XXX

Expenses  XXX

  XXX

  XXX

  XXX

          Restructuring and severance            XXX

            XXX

  XXX

            XXX

        Deferred compensation(1)

            XXX

            XXX

  XXX

            XXX

        Amortization of purchased intangibles

            XXX

            XXX

  XXX

            XXX

          Strategic transaction-related costs   XXX

  XXX

  XXX

  XXX

          Real estate-related costs (credits)            XXX

            XXX

  XXX

            XXX

          Foreign exchange transactions (gains) losses  XXX

  XXX

  XXX

  XXX

          Unrealized and realized (gains) losses on assets            XXX

            XXX

  XXX

            XXX

          Litigation matters or settlements  XXX

  XXX

  XXX

  XXX

Adjusted Operating Expenses  $          XXX

 $          XXX

 $          XXX

 $          XXX

Operating Income $          XXX

 $          XXX

 $          XXX

 $          XXX

Adjusted Operating Income $          XXX

 $          XXX

 $          XXX

 $          XXX

1. Includes $X.X million and $X.X million for a change in our non-qualified deferred compensation liability in the third quarter and first nine months of 2025. This impact does not affect net income, because the compensation and benefits change has an equal and offsetting change in investment income.

We will also continue to include the reconciliation for GAAP to non-GAAP Net Income, Net Income Attributable to CME Group and Diluted EPS as shown in the following table.

3

CME Group Inc. and Subsidiaries

Adjusted Net Income, Net Income Attributable to CME Group and Diluted EPS Reconciliation

(dollars in millions, except per share amounts; shares in thousands)

  Quarter Ended

September 30,

  Nine Months Ended

September 30,

  2025  2024  2025  2024

Net Income   $         XXX

  $         XXX

 $        XXX

 $       XXX

Restructuring and severance            XXX

            XXX

  XXX

  XXX

Amortization of purchased intangibles(1)

            XXX

            XXX

  XXX

  XXX

Strategic transaction-related costs (credits)            XXX

            XXX

  XXX

  XXX

Real estate-related costs (credits)            XXX

            XXX

  XXX

  XXX

Foreign exchange transaction (gains) losses            XXX

            XXX

  XXX

  XXX

Unrealized and realized (gains) losses on investments            XXX

            XXX

  XXX

  XXX

Unrealized and realized (gains) losses on assets            XXX

            XXX

  XXX

  XXX

Litigation matters or settlements            XXX

            XXX

  XXX

  XXX

Income tax effect related to above            XXX

            XXX

  XXX

  XXX

Other income tax items            XXX

            XXX

  XXX

  XXX

Adjusted Net Income  $ XXX

 $ XXX

 $ XXX

 $ XXX

Adjusted Net Income Attributable to Common Shareholders of CME Group $ XXX

 $ XXX

 $ XXX

 $ XXX

Earnings per Share Attributable to Common Shareholders of CME Group:

     Basic   $    XXX

 $    XXX

 $    XXX

 $    XXX

     Diluted            XXX

            XXX

            XXX

            XXX

Adjusted Earnings per Share Attributable to Common Shareholders of CME Group:

     Basic $    XXX

 $    XXX

 $    XXX

 $    XXX

     Diluted            XXX

            XXX

            XXX

            XXX

Weighted Average Number of Common Shares:

     Basic            XXX

            XXX

            XXX

            XXX

     Diluted            XXX

            XXX

            XXX

            XXX

Preferred shares(2)

            XXX

            XXX

            XXX

            XXX

1. Includes $X.X million and $X.X million of amortization of purchased intangibles (net of tax) at OSTTRA and $X.X million and $X.X million of amortization of purchased intangibles at S&P Dow Jones Indices LLC in the third quarter and first nine months of 2025. This is reported in Equity in net earnings of unconsolidated subsidiaries on the Consolidated Statements of Income.

2. Preferred shares have similar rights as common shares without voting rights.

4

In addition, the Company acknowledges:

•the Company is responsible for the adequacy and accuracy of the disclosures in the filing;

•Staff comments or changes to disclosures in response to Staff comments do not foreclose the Commission from taking any action with respect to the filing; and

•the Company may not assert Staff comments as a defense in any proceeding initiated by the Commission or any person under the federal securities laws in the United States.

Please do not hesitate to call me at 312-930-1309 if you have any questions or would like any additional information regarding this matter.

Sincerely,

/s/ Lynne Fitzpatrick

_______________________________________

Lynne Fitzpatrick

President & Chief Financial Officer

CME Group Inc.

5

September 12, 2025
Lynne Fitzpatrick
President & Chief Financial Officer
CME GROUP INC.
20 South Wacker Drive
Chicago, Illinois 60606
Re:CME GROUP INC.
Form 10-K for Fiscal Year Ended December 31, 2024
Form 8-K Filed July 23, 2025
File No. 001-31553
Dear Lynne Fitzpatrick:
            We have limited our review of your filing to the financial statements and related
disclosures and have the following comments.
            Please respond to this letter within ten business days by providing the requested
information or advise us as soon as possible when you will respond. If you do not believe a
comment applies to your facts and circumstances, please tell us why in your response.
            After reviewing your response to this letter, we may have additional comments.
Form 10-K for Fiscal Year Ended December 31, 2024
Notes to Consolidated Financial Statements
Note 18. Segment Reporting, page 82
1.Please represent to us that you will revise future filings to include the geographic
disclosures under ASC 280-10-50-41. Otherwise, tell us why they are not required.
Form 8-K Filed July 23, 2025
Exhibit 99.1, page General
2.You reference Adjusted Operating Income and state that you recorded all-time record
Adjusted Operating Income in the second quarter of 2025. We note that you do not
quantify Adjusted Operating Income or include a reconciliation from a GAAP
measure to this non-GAAP measure. Please either remove reference to this non-
GAAP measure in future releases furnished on Forms 8-K, or advise otherwise as to
why it is a meaningful and useful measure and include all of the disclosure
requirements of Item 10(e) or Regulation S-K.

September 12, 2025
Page 2
            In closing, we remind you that the company and its management are responsible for
the accuracy and adequacy of their disclosures, notwithstanding any review, comments,
action or absence of action by the staff.
            Please contact David Irving at 202-551-3321 or Mark Brunhofer at 202-551-3638
with any questions.
Sincerely,
Division of Corporation Finance
Office of Crypto Assets
cc:Jonathan Marcus

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 February 27, 2025

VIA EDGAR TRANSMISSION

Securities and Exchange Commission

450 Fifth Street, N.W.

Washington, D.C. 20549

Re:    Filing of CME Group Inc. Annual Report on Form 10-K for the year ended December 31, 2024

Ladies and Gentlemen:

On behalf of CME Group Inc., a Delaware corporation (the “Company”), transmitted herewith for filing is the Company’s Annual Report on Form 10-K for the year ended December 31, 2024.

There have not been any changes from the preceding year in any accounting principles or practices, or in the method of applying any such principles or practices, other than the adoption of the Financial Accounting Standards Board's Accounting Standards Update No. 2023-07 Segment Reporting - Improvements to Reportable Segment Disclosures.

If you have any questions or comments in connection with the foregoing, please contact me at (312) 930-3305. Email transmissions may be sent to the undersigned at meg.wright@cmegroup.com.

Very truly yours,

/s/ Meg Wright

Executive Director, Associate General Counsel & Corporate Secretary

1

CMEG--

United States securities and exchange commission logo
October 25, 2022
Terrence A. Duffy
Chief Executive Officer
CME Group Inc.
20 South Wacker Drive
Chicago, Illinois 60606
Re:CME Group Inc.
Definitive Proxy Statement on Schedule 14A
Filed March 17, 2022
File No. 001-31553
Dear Terrence A. Duffy:
            We have completed our review of your filing.  We remind you that the company and its
management are responsible for the accuracy and adequacy of their disclosures, notwithstanding
any review, comments, action or absence of action by the staff.
Sincerely,
Division of Corporation Finance
Disclosure Review Program

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September 30, 2022

U.S. Securities and Exchange Commission

Division of Corporate Finance

Disclosure Review Program

100 F Street, N.E.

Washington, D.C. 20549

ATTN:  Amanda Ravitz

    Barbara Jacobs

Filed Via EDGAR as Correspondence

RE:     CME Group Inc.

Definitive Proxy Statement on Schedule 14A

Filed March 17, 2022

File No. 001-31553

This letter sets forth the responses of CME Group Inc. (“CME Group”, “the Company”, “we”, “our” or “us”) to the comments of the Staff of the U.S. Securities and Exchange Commission  “Staff”) from comment letter dated September 21, 2022 with respect to the above referenced Proxy Statement. For your convenience, we have duplicated the original comments of the Staff as set forth in the comment letter below in italics in providing our responses to each of the Staff’s comments.

Definitive Proxy Statement on Schedule 14A filed March 17, 2022

General

1.     Please expand your discussion of the reasons you believe that your leadership structure is appropriate, addressing your specific characteristics or circumstances. In your discussion, please also address how the experience of your Lead Director is brought to bear in connection with your board’s role in risk oversight.

CME Response:

It is our belief that the Company’s disclosures in the Proxy Statement comply with all applicable rules and regulations, including Item 407(h) of Regulation S-K. Nonetheless, we will consider the Staff’s comments in due course as we evaluate the extent to which we voluntarily supplement our required disclosures in the future.

2.     Please expand upon the role that your Lead Director plays in the leadership of the board. For example, please enhance your disclosure to address whether or not your Lead Director may:

•represent the board in communications with shareholders and other stakeholders; and

•require board consideration of, and/or override your CEO on, any risk matters.

CME Response:

It is our belief that the Company’s disclosures in the Proxy Statement comply with all applicable rules and regulations, including Item 407(h) of Regulation S-K. Nonetheless, we will consider

cmegroup.com         CME GROUP CONFIDENTIAL

the Staff’s comments in due course as we evaluate the extent to which we voluntarily supplement our required disclosures in the future.

3.     Please expand upon how your board administers its risk oversight function. For example, please disclose:

•the specific risks over which the board elected to retain direct oversight responsibility and why oversight of those risks was not assigned to a board committee;

•the timeframe over which you evaluate risks (e.g., short-term, intermediate-term, or long-term) and how you apply different oversight standards based upon the immediacy of the risk assessed;

•whether you consult with outside advisors and experts to anticipate future threats and trends, and how often you re-assess your risk environment;

•how the board interacts with management to address existing risks and identify significant emerging risks;

•whether you have a Chief Compliance Officer and to whom this position reports; and

•how your risk oversight process aligns with your disclosure controls and procedures.

CME Response:

It is our belief that the Company’s disclosures in the Proxy Statement comply with all applicable rules and regulations, including Item 407(h) of Regulation S-K. Nonetheless, we will consider the Staff’s comments in due course as we evaluate the extent to which we voluntarily supplement our required disclosures in the future.

*   *   *

Please do not hesitate to call me at 312-930-8492 if you have any questions or would like any additional information regarding this matter.

Sincerely,

/s/ Terrence A. Duffy

Terrence A. Duffy

Chairman and Chief Executive Officer

CME Group Inc.

cmegroup.com         CME GROUP CONFIDENTIAL

United States securities and exchange commission logo
September 21, 2022
Terrence A. Duffy
Chief Executive Officer
CME Group Inc.
20 South Wacker Drive
Chicago, Illinois 60606
Re:CME Group Inc.
Definitive Proxy Statement on Schedule 14A
Filed March 17, 2022
File No. 001-31553
Dear Mr. Duffy:
            We have limited our review of your most recent definitive proxy statement to those issues
we have addressed in our comments.
            Please respond to these comments by confirming that you will enhance your future proxy
disclosures in accordance with the topics discussed below as well as any material developments
to your risk oversight structure. For guidance, refer to Item 407(h) of Regulation S-K.
Definitive Proxy Statement on Schedule 14A filed March 17, 2022
General
1.Please expand your discussion of the reasons you believe that your leadership structure is
appropriate, addressing your specific characteristics or circumstances. In your discussion,
please also address how the experience of your Lead Director is brought to bear in
connection with your board’s role in risk oversight.
2.Please expand upon the role that your Lead Director plays in the leadership of the board.
For example, please enhance your disclosure to address whether or not your Lead Director
may:
•represent the board in communications with shareholders and other stakeholders; and
•require board consideration of, and/or override your CEO on, any risk matters.
3.Please expand upon how your board administers its risk oversight function. For example,
please disclose:
•the specific risks over which the board elected to retain direct oversight responsibility
and why oversight of those risks was not assigned to a board committee;
•the timeframe over which you evaluate risks (e.g., short-term, intermediate-term, or

 FirstName LastNameTerrence A. Duffy
 Comapany NameCME Group Inc.
 September 21, 2022 Page 2
 FirstName LastName
Terrence A. Duffy
CME Group Inc.
September 21, 2022
Page 2
long-term) and how you apply different oversight standards based upon the
immediacy of the risk assessed;
•whether you consult with outside advisors and experts to anticipate future threats and
trends, and how often you re-assess your risk environment;
•how the board interacts with management to address existing risks and identify
significant emerging risks;
•whether you have a Chief Compliance Officer and to whom this position reports; and
•how your risk oversight process aligns with your disclosure controls and procedures.
            We remind you that the company and its management are responsible for the accuracy
and adequacy of their disclosures, notwithstanding any review, comments, action or absence of
action by the staff.
            Please contact Amanda Ravitz at 202-551-3412 or Barbara Jacobs at 202-551-3735 with
any questions.
Sincerely,
Division of Corporation Finance
Disclosure Review Program

December 20, 2019
John Pietrowicz
Chief Financial Officer
CME Group, Inc.
20 South Wacker Drive
Chicago, IL 60606
Re:CME Group, Inc.
Form 10-K for the Fiscal Year Ended December 31, 2018
Filed February 28, 2019
File No. 001-31553
Dear Mr. Pietrowicz:
            We have completed our review of your filings.  We remind you that the company and its
management are responsible for the accuracy and adequacy of their disclosures, notwithstanding
any review, comments, action or absence of action by the staff.
Sincerely,
Division of Corporation Finance
Office of Finance

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December 19, 2019

Via EDGAR

United States Securities and Exchange Commission

Division of Corporation Finance

100 F Street, N.E. Washington, D.C. 20549

ATTN: Mr. Robert Klein

Mr. Hugh West, Branch Chief

RE:    CME Group, Inc.

Form 10-K for the Fiscal Year Ended December 31, 2018

Filed February 28, 2019

File No. 001-31553

Dear Gentlemen:

This letter sets forth the responses of CME Group Inc. (“CME”, “the Company”, “we”, “our” or “us”) to the comments of the Staff of the U.S. Securities and Exchange Commission (the “Staff”) from comment letter dated December 5, 2019 with respect to the above referenced Form 10-K. For your convenience, we have duplicated the original comments of the Staff as set forth in the comment letter below in italics in providing our responses to each of the Staff’s comments.

Form 10-K for the Fiscal Year Ended December 31, 2018 Notes to Consolidated Financial Statements

3. Business Combinations, page 62

1.

 We note that you completed the acquisition of NEX Group plc (NEX) on November 2, 2018 and, as disclosed in Exhibit 99.1 in your Form 8-K filed on November 8, 2018, that the pro forma 2017 annual revenues would be $4.3 billion giving effect to the acquisition, compared to your actual 2017 GAAP revenues of $3.6 billion. However, it is not clear where you have disclosed all information required by ASC 805 for this acquisition, such as the amounts of post-acquisition revenues and earnings or supplemental pro forma revenues and earnings required by ASC 805-10-50-2(h). In your future filings, please revise to disclose all information required by ASC 805-10-50 or tell us why you do not think it is required.

CME Response:

We propose to include the following disclosure within footnote 3 Business Combinations in our Form 10-K for the fiscal year ended December 31, 2019:

On November 2, 2018, the company completed its acquisition of NEX and its subsidiaries. For the two-month period ended December 31, 2018, NEX revenues and net losses, which include transaction-related costs, were $133.6 million and ($42.5) million respectively.

The following table presents pro forma information as if the acquisition of NEX had occurred on January 1, 2017. This pro forma information combines the historical condensed consolidated results of operations of CME and NEX after giving effect to certain adjustments, including purchase accounting fair value adjustments, amortization of intangibles, stock-based compensation expense and acquisition costs, as well as the related income tax effects of those adjustments. The pro forma information does not necessarily reflect the results of operations that would have occurred had the company acquired NEX on January 1, 2017. Furthermore, cost savings and other business synergies related to the acquisition are not reflected in the pro forma amounts.

(in millions)

 2018

 2017

Total revenues

 $

 4,983.8

 $

 4,388.4

Net income

 2,030.8

 4,043.3

2.

 Please provide us with a summary of the income significance test pursuant to Rule 1-02(w) of Regulation S-X prepared in your determination of whether audited financial statements of NEX and full pro forma financial information should be provided pursuant to Rule 3-05 and Article 11 of Regulation S-X, respectively.

CME Response:

When an SEC registrant consummates or it is probable that it will consummate a significant business acquisition, SEC Regulation S-X Rule 3-05 (Rule 3-05) may require the filing of certain financial statements for the acquired or to be acquired business. For example, the registrant may be required to file a Form 8-K with financial statements for a significant acquiree. The determination as to whether an acquisition represents a “significant” business acquisition involves three tests:

A.

 Asset Test: Compare CME’s share of NEX’s total assets to CME’s consolidated total assets.

B.

 Investment Test: Compare total purchase price of NEX to CME’s total assets.

C.

 Income Test: Compare CME’s equity in NEX’s income from continuing operations before taxes, extraordinary items and cumulative effect of a change in accounting principle to that of CME’s net income.

All three tests must be performed, and the one that results in the highest significance level will determine the financial statement periods that must be presented. The threshold begins at 20% for such financial statement requirements under Rule 3-05. The below table presents the results

of the significance tests performed as of March 31, 2018 for NEX and December 31, 2017 for CME - the most recent pre-acquisition annual financial statements that are required to be filed with the SEC should generally be used for the significance tests.

 Test

(in millions)

 NEX

 CME

 Result

Asset Test

 $

 2,414.4

 $

 75,791.2

 3%

Investment Test

 5,600.0

 75,791.2

 7%

Income Test

 174.6

 2,526.3

 7%

As the NEX acquisition does not meet the 20% threshold noted above, the disclosure of audited financial statements and other pro forma information in accordance with SEC Regulation S-X Rule 3-05 (Rule 3-05) is not required.

In addition, at the Staff’s request, the Company acknowledges:

•

 the Company is responsible for the adequacy and accuracy of the disclosures in the filing;

•

 Staff comments or changes to disclosures in response to Staff comments do not foreclose the Commission from taking any action with respect to the filing; and

•

 the Company may not assert Staff comments as a defense in any proceeding initiated by the Commission or any person under the federal securities laws in the United States.

Please do not hesitate to call me at 312-930-4596 if you have any questions or would like any additional information regarding this matter.

Sincerely,

/s/ John Pietrowicz

John Pietrowicz

Senior Managing Director & Chief Financial Officer

CME Group Inc.

December 5, 2019
John Pietrowicz
Chief Financial Officer
CME Group, Inc.
20 South Wacker Drive
Chicago, IL 60606
Re:CME Group, Inc.
Form 10-K for the Fiscal Year Ended December 31, 2018
Filed February 28, 2019
File No. 001-31553
Dear Mr. Pietrowicz:
            We have reviewed your filing and have the following comments.  In some of our
comments, we may ask you to provide us with information so we may better understand your
disclosure.
            Please respond to these comments within ten business days by providing the requested
information or advise us as soon as possible when you will respond.  If you do not believe our
comments apply to your facts and circumstances, please tell us why in your response.
            After reviewing your response to these comments, we may have additional comments.
Form 10-K for the Fiscal Year Ended December 31, 2018
Notes to Consolidated Financial Statements
3. Business Combinations, page 62
1.We note that you completed the acquisition of NEX Group plc (NEX) on November 2,
2018 and, as disclosed in Exhibit 99.1 in your Form 8-K filed on November 8, 2018, that
the pro forma 2017 annual revenues would be $4.3 billion giving effect to the acquisition,
compared to your actual 2017 GAAP revenues of $3.6 billion. However, it is not clear
where you have disclosed all information required by ASC 805 for this acquisition, such
as the amounts of post-acquisition revenues and earnings or supplemental pro forma
revenues and earnings required by ASC 805-10-50-2(h). In your future filings, please
revise to disclose all information required by ASC 805-10-50 or tell us why you do not
think it is required.

 FirstName LastNameJohn Pietrowicz
 Comapany NameCME Group, Inc.
 December 5, 2019 Page 2
 FirstName LastName
John Pietrowicz
CME Group, Inc.
December 5, 2019
Page 2
2.Please provide us with a summary of the income significance test pursuant to Rule 1-
02(w) of Regulation S-X prepared in your determination of whether audited financial
statements of NEX and full pro forma financial information should be provided pursuant
to Rule 3-05 and Article 11 of Regulation S-X, respectively.
            We remind you that the company and its management are responsible for the accuracy
and adequacy of their disclosures, notwithstanding any review, comments, action or absence of
action by the staff.
            You may contact Robert Klein at 202-551-3847 or Hugh West, Branch Chief, at 202-
551-3872 if you have questions regarding comments on the financial statements and related
matters.
Sincerely,
Division of Corporation Finance
Office of Finance

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		Document

 February 28, 2019

VIA EDGAR TRANSMISSION

Securities and Exchange Commission

450 Fifth Street, N.W.

Washington, D.C. 20549

Re:

 Filing of CME Group Inc. Annual Report on Form 10-K for the year ended December 31, 2018

Ladies and Gentlemen:

On behalf of CME Group Inc., a Delaware corporation (the “Company”), transmitted herewith for filing is the Company’s Annual Report on Form 10-K for the year ended December 31, 2018.

There have not been any changes from the preceding year in any accounting principles or practices, or in the method of applying any such principles or practices, other than the adoption of the Financial Accounting Standards Board's Accounting Standards Update No. 2014-09—REVENUE FROM CONTRACTS WITH CUSTOMERS (TOPIC 606), Accounting Standards Update No. 2016-01—FINANCIAL INSTRUMENTS—OVERALL (SUBTOPIC 825-10): RECOGNITION AND MEASUREMENT OF FINANCIAL ASSETS AND FINANCIAL LIABILITIES, Accounting Standards Update No. 2016-18—STATEMENT OF CASH FLOWS (TOPIC 230): RESTRICTED CASH, Accounting Standards Update No. 2017-07—COMPENSATION—RETIREMENT BENEFITS (TOPIC 715): IMPROVING THE PRESENTATION OF NET PERIODIC PENSION COST AND NET PERIODIC POSTRETIREMENT BENEFIT COST, Accounting Standards Update No. NO. 2017-12—DERIVATIVES AND HEDGING (TOPIC 815): TARGETED IMPROVEMENTS TO ACCOUNTING FOR HEDGING ACTIVITIES, Accounting Standards Update No. 2018-02—INCOME STATEMENT—REPORTING COMPREHENSIVE INCOME (TOPIC 220): RECLASSIFICATION OF CERTAIN TAX EFFECTS FROM ACCUMULATED OTHER COMPREHENSIVE INCOME, and Accounting Standards Update No. 2018-13—FAIR VALUE MEASUREMENT (TOPIC 820): DISCLOSURE FRAMEWORK—CHANGES TO THE DISCLOSURE REQUIREMENTS FOR FAIR VALUE MEASUREMENT.

If you have any questions or comments in connection with the foregoing, please contact me at (312) 930-3305. Facsimile transmissions may be sent to the undersigned at (312) 930-4556.

Very truly yours,

/s/ Meg Wright

Executive Director, Associate General Counsel & Assistant Corporate Secretary

1

CMEG--

July 16, 2014

Via E -Mail
James E. Parisi
Chief Financial  Officer
CME Group Inc.
20 South Wacker Drive
Chicago, IL   60606

                 Re: CME Group Inc.
                        Form 10 -K for the Fiscal Ye ar Ended December  31, 20 13
Filed March 3,  2014
File No. 001 -31553

Dear Mr. Parisi :

We have completed our review of your filing.  We remind you that our comments
or changes to disclosure in response to our comments do not foreclose the Commission
from taking any action with respect to the company or the filing s and the company may
not ass ert staff comments as a defense in any proceeding initiated by the Commission or
any person under the federal securities laws of the United States.  We urge all persons
who are responsible for the accuracy and adequacy  of the disclosure in the filings  to be
certain that the filing s include the information the Securities Exchange Act of 1934 and
all applicable rules require.

                                                                                    Sincerely,

        /s/ Daniel L. Gordon

Daniel L. Gordon
                                                                                    Branch Chief

CORRESP
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		June 2014 SEC Comment Letter

July 1, 2014

Via EDGAR

Division of Corporate Finance

United States Securities and Exchange Commission

100 F Street, NE

Washington, D.C. 20549-6010

Attention:

 Daniel L. Gordon, Branch Chief

 Jorge L. Bonilla

RE:

 CME Group Inc. Form 10-K for the fiscal year ended December 31, 2013, filed March 3, 2014, File No. 001-31553

Dear Mr. Gordon:

CME Group Inc.  (the “Company”) has received the comment from the staff of the Division of Corporation Finance (the “Staff”) of the Securities and Exchange Commission (the “Commission”) contained in your letter, dated May 30, 2014, regarding the Commission’s review of the above-referenced Company filing (the “Comment Letter”).  The Company hereby submits its response to the Staff’s comment contained in the Comment Letter, as set forth below.  For the convenience of the Staff, the Staff’s comment has been reproduced below and is set forth in bold and italics immediately prior to the Company’s response.

Form 10-K for the Fiscal Year Ended December 31, 2013 filed March 3, 2014

Cash Requirements, page 46

1.

 We note your disclosure on page 47 that debt obligations include repayment of the debt obligation as well as interest payments associated with the debt obligations. We also note that the amount of debt obligations included within the contractual obligations table on page 46 approximates the principal amount disclosed in note 8 on page 71. Please tell us the amount of interest payments included in your contractual obligations table, the contractual terms of your debt agreements relating to interest payments, and reconcile to the disclosure in note 8.

Response:

The tabular contractual obligations disclosure on page 46 did not include interest payments associated with the debt obligations. The tabular contractual obligations disclosure and the long-term debt maturities table in Note 8 both include the principal amount of the debt obligations. Interest on the Company’s debt obligations is paid semiannually in arrears based on the stated rate.  Had the tabular contractual obligations disclosure included interest payments as of December 31, 2013, the debt obligations column would have increased by the following amounts (in millions):

Year

 Amount

2014

 $

 110.8

2015-2016

 178.4

2017-2018

 164.9

Thereafter

 1,083.8

The disclosures within Note 8 on page 71 and Liquidity and Capital Resources - Debt Instruments on page 48 include par value, stated rate and maturity date for each debt obligation, which can be used to calculate future interest payments. In future filings, the Company will include all applicable obligations that fall within the specified categories of Item 303(a)(5)(i) of Regulation S-K within the contractual obligations table, including interest commitments for interest-bearing debt.

Acknowledgement

In connection with the Company’s response to the Staff’s comments, the Company hereby acknowledges that:

•

 The Company is responsible for the adequacy and accuracy of the disclosure in the filing;

•

 Staff comments or changes to disclosure in response to Staff comments do not foreclose the Commission from taking any action with respect to the filing; and

•

 The Company may not assert Staff comments as a defense in any proceeding initiated by the Commission or any person under the federal securities laws of the United States.

If the Staff has any questions, concerns or additional comments regarding the foregoing, please contact me at (312) 930-3488 (phone) or (312) 930-4556 (fax).

Sincerely,

Kathleen M. Cronin

Senior Managing Director, General Counsel and

Corporate Secretary

May 30, 2014

Via E -Mail
James E. Parisi
Chief Financial  Officer
CME Group Inc.
20 South Wacker Drive
Chicago, IL   60606

                 Re: CME Group Inc.
                        Form 10 -K for the Fiscal Ye ar Ended December  31, 20 13
Filed March 3,  2014
File No. 001 -31553

Dear Mr. Parisi :

We have reviewed your filing an d have the following comments.  In some of our
comments, we may ask you to provide us with information so we may better understand
your disclosure.

Please respond to this letter within ten business days by amending your filing, by
providing the requested information, or by advising us when you will provide the
requested response.   If you do not believe our comments apply to your facts and
circumstances or do not believe an amendment is appropriate, please tell us why in your
response .

After reviewing any amendment to your filing and the information you provide in
response to these  comments, we may have  additional comments.

Form 10 -K for the Fiscal Year Ended December  31, 201 3 filed March 3 , 201 4

Cash Requirements , page 46

1. We note your disclosure on page 47 that debt obligations include repayment of
the debt obligation as well as interest payments associated with the debt
obligations. We also note that the amount of debt obligations included within the
contractual obligation s table on page 46 approximates the principal amount
disclosed in note 8 on page 71. Please tell us the amount of interest payments
included in your contractual obligations table, the contractual terms of your debt
agreements relating to interest payments,  and reconcile to the disclosure in note 8.

James E. Parisi
CME Group  Inc.
May 30, 2014
Page 2

 We urge all persons who are responsible for the accuracy and adequacy of the
disclosure in the filing to be certain that the filing includes the information the Securities
Exchange Act of 1934 and all applicable Exchange Act rules require.   Since the company
and its management are in possession of all facts relating to a company’s disclosure, they
are responsible for the accuracy and adequacy of the disclosures they have made.

 In res ponding to our comments, please provide a written statement from the
company acknowledging that:

 the company is responsible for the adequacy and accuracy of the disclosure in the
filing;

 staff comments or changes to disclosure in response to staff comments do not
foreclose the Commission from taking any action with respect to the filing; and

 the company may not assert staff comments as a defense in any proceeding
initiated by the Commission or any person under the federal securities laws of the
United States.

If you have any questions, you may contact Jorge L. Bonilla at (202) 551 -3414 or
me at (202) 551 -3486.

                                                                                    Sincerely,

        /s/ Daniel L. Gordon

Daniel L. Gordon
                                                                                    Branch Chief

June 1 9, 2013

Via E -mail
Mr. James E. Parisi
Chief Financial Officer  & Senior Managing Director
Finance and  Corporate  Development
CME  Group Inc.
20 South Wacker Drive
Chicago , IL 60606

Re: CME Group  Inc.
 Form 10 -K for the Year Ended December 31 , 2012
 Filed March 1, 2013
File No. 001-31553

Dear Mr. Parisi :

We have completed our review of your filing.  We remind you that our comments or
changes to disclosure in response to our comments do not foreclose the Commission from taking
any action with respect to the company or the filing and the company may not assert staff
comments as a defense in any proceeding initiated by the Commission or any person under the
federal securities la ws of the United States.  We urge all persons who are responsible for the
accuracy and adequacy of the disclosure in the filing to be certain that the filing includes the
information the Securities Exchange Act of 1934 and all applicable rules require.

Sincerely,

 /s/ Jonathan Wiggins

Jonathan Wiggins
Staff Accountant

CORRESP
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		May 2013 Comment Letter

May 30, 2013

Via EDGAR

Division of Corporate Finance

United States Securities and Exchange Commission

100 F Street, NE

Washington, D.C. 20549-6010

Attention:     Jonathan Wiggins, Staff Accountant

Eric McPhee

RE:

 CME Group Inc. Form 10-K for the fiscal year ended December 31, 2012, filed March 1, 2013, File No. 001-31553

Dear Mr. Wiggins:

CME Group Inc.  (the “Company”) has received the comments from the staff of the Division of Corporation Finance (the “Staff”) of the Securities and Exchange Commission (the “Commission”) contained in your letter, dated May 9, 2013, regarding the Commission's review of the above-referenced Company filing (the “Comment Letter”).  The Company hereby submits its response to the Staff's comments contained in the Comment Letter, as set forth below.  For the convenience of the Staff, each of the Staff's comments has been reproduced below and is set forth in bold and italics immediately prior to the Company's response.

Form 10-K for the Year Ended December 31, 2012

Item 7. Management's Discussion and Analysis of Financial Condition…, page 35

Revenues, page 37

1.

 Please tell us how you account for the incentive programs that you use to promote trading and describe for us and tell us how you account for the broker rebates disclosed on page 39, citing the authoritative literature upon which you relied.

Response:

Trading incentive programs are accounted for under FASB ASC Subtopic 605-50, Revenue Recognition-Customer Payments and Incentives (ASC 605-50). Trading incentives are offered to customers in three forms - discounts, free services and rebates. Revenues for discounted trades are recorded at the reduced rates. When trading fees are waived, no revenue is recognized. When trading rebates are offered, they are accrued as the obligation is incurred and are presented in the income statement net of the associated revenues.

The Company also offers commissions (referred to as broker rebates on page 39 of Form 10-K for the year ended December 31, 2012) to intermediary brokers who physically enter certain eligible trades into our system on behalf of third parties.  In order to be eligible for commission, the broker cannot be a party to the trade. Since the broker does not participate in the trade, the broker is not considered a customer as defined in ASC 605-50. Commissions are accrued in other current liabilities as eligible trades are

received. Commissions are included in licensing and fee arrangements expense in the income statement.

Liquidity and Capital Resources, page 50

2.

 In future filings, please revise your tabular presentation of contractual obligations to include all of the obligations that fall within the specified categories of Item 303(a)(5)(i) of Regulation S-K, including long-term debt obligations.  Your disclosure should also include your interest commitments under your interest-bearing debt in this table, or provide textual discussion of this obligation below the table.  If you provide a textual discussion, the discussion should quantify the interest payments using the same time frames stipulated in the table.

Response:

In future filings, the Company will include all applicable obligations that fall within the specified categories of Item 303(a)(5)(i) of Regulation S-K within the contractual obligations table, including long-term debt obligations and any related interest commitments under interest-bearing debt included in the table.

Note 2. Summary of Significant Accounting Policies, page 66

Goodwill and Other Intangible Assets, page 67

3.

 In future filings, please revise to disclose your accounting policies related to intangible assets subject to amortization.

Response:

Accounting policies related to intangible assets subject to amortization are included in the Critical Accounting Policies section of Management's Discussion and Analysis of Financial Conditions and Results of Operations in the Company's Form 10-K for the year ended December 31, 2012. In the future, the Company will include these policies in Note 2, Summary of Significant Accounting Policies in its Form 10-K.

Segment Reporting, page 69

4.

 Please tell us how you determined that you had one reportable segment and that CME, CBOT, NYMEX, COMEX and KCBT are one operating segment.

Response:

FASB ASC Topic 280, Segment Reporting (ASC 280) defines an operating segment as a component of a public entity that has all of the following characteristics:

a. It engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same public entity).

b. Its operating results are regularly reviewed by the public entity's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance.

c. Its discrete financial information is available.

Each of these entities - CME, CBOT, NYMEX, COMEX and KCBT - engages in business activities from which it may earn revenues and incur expenses. Additionally, the Company provides discrete financial information for CME, CBOT, NYMEX, COMEX and KCBT to the U.S. Commodities Futures Trading Commission (CFTC) to meet regulatory reporting requirements. The Company also publishes discrete

financial statements for CME under an exemptive order issued by the Commission.  Although discrete financial information is reviewed regularly by the Company's Accounting Department to ensure that each of these entities meets regulatory requirements, the Company's chief operating decision maker, as defined by ASC 280, does not review discrete financial information for these entities.  Based on the content of information reviewed by the Company's chief operating decision maker to make decisions about resource allocation and assess performance, CME, CBOT, NYMEX, COMEX and KCBT do not separately meet the definition of operating segment under ASC 280. Aside from these entities, the Company's other businesses, although qualifying as operating segments under ASC 280, do not meet the thresholds for separate disclosure under ASC 280. As a result, the Company has only one reportable segment.

Note 14. Contingencies, page 84

5.

 In future filings, please revise to disclose the amount of reasonably possible losses or range of losses in excess of amounts accrued for all legal proceedings and other contingencies or, where applicable, to state that such an estimate of the possible loss or range of loss cannot be made.  We note that you provide such disclosure for the lawsuits related to MF Global only.  You may provide your disclosures on an aggregated basis.  Refer to ASC 450-20-50.  Please provide us with your proposed disclosure.

Response:

In future filings, in accordance with FASB ASC Section 450-20-50, Contingencies-Loss Contingencies-Disclosure, for proceedings where an accrued liability has not been established but we believe a loss is reasonably possible, we will either provide a current estimate of the range of possible loss if the determination is possible and the loss is material or we will indicate that the range of possible loss cannot be estimated.

In connection with both the Garber, Fifth Market and Realtime matters, the Company filed requests with the U.S. Patent and Trademark Office (USPTO) to re-examine the validity of the patents at issue. These re-examinations may result in various outcomes, including decisions on the validity of the patents at issue, and the timing of the decisions of the USPTO is uncertain. We expect the decisions of the USPTO to impact the merits of the cases. In light of the uncertainty of the decisions of the USPTO and their impact on the merits of the underlying cases, the Company is unable to determine a range of reasonably possible loss during the pendency of these reviews. We will update our disclosures accordingly upon their resolution.

The Company plans to include the following disclosure in its next periodic report with such updates that occur prior to the filing of the report, if any:

In 2008, Fifth Market, Inc. (Fifth Market) filed a complaint against CME Group and CME seeking a permanent injunction against CME's Globex system and unquantified enhanced damages for what the plaintiff alleges is willful infringement of two U.S. patents, in addition to costs, expenses and attorneys' fees. Beginning in March 2012, the case was stayed pending the outcome of reexamination by the U.S. Patent and Trademark Office (USPTO) to determine the validity of the patents at issue. Based on its investigation to date and advice from legal counsel, the company believes this suit is without merit and intends to defend itself vigorously against these charges.

In 2009, CME and CBOT filed a complaint against Howard Garber seeking a declaratory judgment that neither CME nor CBOT infringed the Garber patent and that the patent is invalid and unenforceable. Beginning in June 2011, the case was stayed pending the outcome of the reexamination by the USPTO to determine the validity of the patent at issue. Based on its investigation to date and advice from legal counsel, the company believes this suit is without merit and intends to defend itself vigorously against these charges.

In 2009, Realtime Data LLC (Realtime) filed a complaint against CME Group and other exchanges alleging willful infringement of four patents which was later amended to add CBOT and NYMEX as defendants. Subsequently, two additional lawsuits have been filed each adding a claim for the infringement of an additional patent. Both of these lawsuits have been consolidated with the original action. Realtime is seeking a permanent injunction, enhanced damages, attorneys' fees and costs. The court entered judgment in CME's favor in September 2012 based on invalidity and non-infringement. Realtime Data filed its appeal brief in March 2013. The USPTO is conducting a parallel review of the patents at issue. Based on its investigation to date and advice from legal counsel, the company believes this suit is without merit and intends to defend itself vigorously against these charges.

The foregoing legal matters involve alleged infringements of intellectual property, which due to their nature involve potential liability that is uncertain, difficult to quantify and involve a wide range of potential outcomes. The company believes that the matters are without merit and intends to defend itself vigorously against the claims. We expect the re-examinations by the USPTO in the Fifth Market,  Garber and Realtime matters to result in a determination of the validity of the patents at issue which we expect will have an impact on the merits of the matters. Given the uncertainty of the potential outcome of the re-examinations as well as other factors which may potentially impact the resolution of these matters, at this time the company is unable to estimate the reasonably possible loss or range of reasonably possible loss in the unlikely event it were found to be liable at trial in these matters.

Form 8-K Filed February 5, 2013

Exhibit 99.1

6.

 Please note that it is generally not appropriate to present a full non-GAAP income statement for purposes of reconciling non-GAAP measures to the most directly comparable GAAP measures.  Refer to Question 102.10 of the Compliance & Disclosure Interpretation on Non-GAAP Financial Measures.

Response:

We note the Staff's comment and will comply with Question 102.10 of the Compliance & Disclosure Interpretation on Non-GAAP Financial Measures in future filings. The Company included an Exhibit 99.1 with its Form 8-K filed on May 2, 2013 which complied with Question 102.10 of the Compliance & Disclosure Interpretation on Non-GAAP Financial Measures.

Acknowledgment

In connection with the Company's response to the Staff's comments, the Company hereby acknowledges that:

•

 The Company is responsible for the adequacy and accuracy of the disclosure in the filing;

•

 Staff comments or changes to disclosure in response to Staff comments do not foreclose the Commission from taking any action with respect to the filing; and

•

 The Company may not assert Staff comments as a defense in any proceeding initiated by the Commission or any person under the federal securities laws of the United States.

If the Staff has any questions, concerns or additional comments regarding the foregoing, please contact me at (312) 930-3488 (phone) or (312) 930-4556 (fax).

Sincerely,

Kathleen M. Cronin

Senior Managing Director, General Counsel and

Corporate Secretary

May 9 , 2013

Via E -mail
Mr. James E. Parisi
Chief Financial Officer  & Senior Managing Director
Finance and  Corporate  Development
CME  Group Inc.
20 South Wacker Drive
Chicago , IL 60606

Re: CME Group  Inc.
 Form 10 -K for the Year Ended December 31 , 2012
 Filed March 1, 2013
File No. 001-31553

Dear Mr. Parisi :

We have reviewed your filing an d have the following comments.  In some of our
comments, we may ask you to provide us with information so we may better understand your
disclosure.

Please respond to this letter within ten business days by amending your filing, by
providing the requested information, or by advising us when you will provide the requested
response.   If you do not  believe our comments apply to your facts and circumstances or do not
believe an amendment is appropriate, please tell us why in your response.

After reviewing any amendment to your filing and the information you provide in
response to these  comments, w e may have  additional comments.

Form 10 -K for the Year Ended December 31 , 2012

Item 7. Management’s Discussion and Analysis of Financial Condition…, page 35

Revenues, page 37

1. Please tell us how you account for the incentive programs that you use to promote trading
and describe for us and tell us how you account for the broker rebates disclosed on page
39, citing the authoritative literature upon which you relied.

Liquidity and Capital Resources, page 50

2. In future filings, please revise your tabu lar presentation of contractual obligations to
include all of the obligations that fall within the specified categories  of Item 303(a)(5)(i)

Mr. James E. Parisi
CME  Group Inc.
May 9 , 2013
Page 2

 of Regulation S -K, including long -term debt obligations.  Your disclosure should also
include your interest commitments under your interest -bearing debt in this table, or
provide textual discussion of this obligation below the table.  If you provide a textual
discussion, the discussion should quantify the interest payments using the same time
frames stipulated i n the table .

Note 2. Summary of Significant Accounting Policies, page 66

Goodwill and Other Intangible Assets, page 67

3. In future filings, please revise to disclose your accounting policies related to intangible
assets subject to amortization.

Segment Reporting, page 69

4. Please tell us how you determined that you had one reportable segment and that CME,
CBOT, NYMEX, COMEX and KCBT are one operating segment.

Note 14. Contingencies, page 84

5. In future filings, please revise to disclose the amount of reas onably possible losses or
range of losses in excess of amounts accrued for all legal proceedings and other
contingencies or, where applicable, to state that such an estimate of the possible loss or
range of loss cannot be made.  We note that you provide su ch disclosure for the lawsuits
related to  MF Global only.  You may provide your disclosures on an aggregated basis.
Refer to ASC 450 -20-50.  Please provide us with your proposed disclosure.

Form 8 -K Filed February 5, 2013

Exhibit 99.1

6. Please note that  it is generally not appropriate to present a full non -GAAP income
statement for purposes of reconciling non -GAAP measures to the most directly
comparable GAAP measures .  Refer to Question 102.10 of the Compliance & Disclosure
Interpretation on Non -GAAP Fina ncial Measures.

We urge all persons who are responsible for the accuracy and adequacy of the disclosure
in the filing to be certain that the filing includes the information the Securities Exchange Act of
1934 and all applicable Exchange Act rules require.   Since the company and its management are
in possession of all facts relating to a company’s disclosure, they are responsible for the accuracy
and adequacy of the disclosures they have made.

 In responding to our comments, please provide  a written stat ement from the company
acknowledging that:

Mr. James E. Parisi
CME  Group Inc.
May 9 , 2013
Page 3

 the company is responsible for the adequacy and accuracy of the disclosure in the filing;

 staff comments or changes to disclosure in response to staff comments do not foreclose
the Commission from taking any action with respect to the filing; and

 the company may not assert staff comments as a defense in any proceeding initiated by
the Commission or any person under the federal securities laws of the United States.

If you have any questions, you may contact E ric McPhee at (202) 551 -3693 or me at
(202) 551 -3694.

Sincerely,

 /s/ Jonathan Wiggins

Jonathan Wiggins
Staff Accountant

July 8, 2011  VIA E-Mail

Mr. James E. Parisi Chief Financial Officer CME Group, Inc. 20 South Wacker Drive Chicago, Illinois 60606
Re: CME Group, Inc.
Form 10-K for the year ended December 31, 2010 Filed February 28, 2011 Form 10-Q for the quarter ended March 31, 2011 Filed May 10, 2011 File No. 001-31553

Dear Mr. James E. Parisi:
We have completed our review of your f iling.  We remind you that our comments or
changes to disclosure in res ponse to our comments do not for eclose the Commission from taking
any action with respect to the company or th e filing and the company may not assert staff
comments as a defense in any proceeding ini tiated by the Commission or any person under the
federal securities laws of the United States.  We urge all pers ons who are responsible for the
accuracy and adequacy of the disclosure in the fi ling to be certain that the filing includes the
information the Securities Exchange Act of 1934 and all applicable rules require.

Sincerely,
  /s/ Daniel L. Gordon   Daniel L. Gordon
Branch Chief

CORRESP
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Response Letter to the SEC

 June 30, 2011

 Via EDGAR

 Division of Corporate Finance

United States Securities and Exchange Commission

100 F Street, NE

 Washington, D.C. 20549-6010

Attention:

Daniel L. Gordon, Branch Chief

Wilson K. Lee

RE:

CME Group Inc. Form 10-K for the fiscal year ended December 31, 2010, filed February 28, 2011, File No. 001-31553

 Dear Mr. Gordon:

 CME Group Inc. (the “Company”) has received the additional comments from the staff of the Division of Corporation Finance (the “Staff”) of the Securities and Exchange Commission (the
“Commission”) contained in your follow up letter, dated June 9, 2011, regarding the Commission’s review of the above-referenced Company filing (the “Comment Letter”). The Company hereby submits its response to the
Staff’s comments contained in the Comment Letter, as set forth below. For the convenience of the Staff, each of the Staff’s comments has been reproduced below and is set forth in bold and italics immediately prior to the Company’s
response.

 Note 18 Contingencies, page 96

 We have considered your response to comment three. Further to our previous comment, for any contingencies where you are unable to estimate a range of reasonably possible losses, please explain the
procedures you undertake on a quarterly basis to attempt to develop a range of reasonably possible loss for disclosure. In addition, to the extent the plaintiff has requested in public filings, a quantified amount please explain why a range of
reasonably possible loss cannot be determined. For cases that have been outstanding for several years we would expect that at some point you would be able to come up with a range of possible loss (i.e., Fifth Market and Real Time).

 Response: In connection with the preparation and filing of its periodic reports, the General Counsel in consultation with the
attorney(s) in the legal department responsible for the Company’s ongoing litigation matters, meets with representatives of the Accounting Department and the external auditors to discuss the status and potential impact of the Company’s
legal matters. The discussion includes the status of the legal matters, including whether any particular quantifiable demands for damages have been made and/or settlement discussions have been authorized as well as other key milestones within the
particular matter that may trigger a change in the disclosure. To the extent that any settlement discussions have been authorized, an associated accrual is included in the Company’s financial statements. Any requests for quantified damages are
assessed for their reasonableness and probability

for recovery should the matter proceed to trial and disclosures are added to the periodic filing accordingly. We establish an accrued liability for legal and regulatory proceedings when those
proceedings present loss contingencies that are both probable and estimable. Any accruals are adjusted as proceedings develop, as appropriate. For proceedings where an accrued liability has not been established but we believe a loss is reasonably
possible, we will provide a current estimate of the range of possible loss if the determination is possible and the loss is material or will indicate that the range of possible loss cannot be estimated. For proceedings where we are unable to
estimate a range of possible loss, we will disclose the potential magnitude of the claim to the extent possible.

 In connection with both the
Garber and Fifth Market matters, the Company filed requests with the U.S. Patent and Trademark Office (USPTO) to re-examine the validity of the patents at issue. Subsequent to our initial response to the Comment Letter, these re-examinations were
granted. As a result, pending the decision of the USPTO, the Garber case has been dismissed with a right to reinstate and the Fifth Market case has been stayed. We expect the decisions from the USPTO to be appealed and a final determination will
take three to five years. These re-examinations may result in various outcomes, including decisions on the validity of the patents at issue. We expect the decisions of the USPTO to impact the merits of the Garber and Fifth Market cases. In light of
the uncertainty of the decisions of the USPTO and their impact on the merits of the underlying cases, the Company is unable to determine a range of reasonably possible losses during the pendency of these reviews. We will update our disclosures
accordingly upon their resolution. We also note that although the Realtime claim has been pending since 2009, the parties have been in dispute regarding the appropriate venue of the matter. As a result, the case has not yet proceeded to the
discovery phase. Absent discovery, the Company is unable to determine a range of reasonably possible losses.

 The Company plans to include the
following disclosure in its next periodic report with such updates that occur prior to the filing of the report, if any:

 In
2008, Fifth Market filed a complaint against CME Group and CME seeking a permanent injunction against CME’s Globex system and unquantified enhanced damages for what the plaintiff alleges is willful infringement of two U.S. patents, in addition
to costs, expenses and attorneys’ fees. The matter has been stayed pending the outcome of a re-examination of the patents at issue by the U.S. Patent and Trademark Office (USPTO). Based on its investigation to date and advice from legal
counsel, the company believes this suit is without merit and intends to defend itself vigorously against these charges.

 In
2009, CME and CBOT filed a complaint against Howard Garber seeking a declaratory judgment that neither CME nor CBOT was infringing certain of Mr. Garber’s patents and that one of his patents is invalid and unenforceable. In 2009,
Technology Research Group LLC, the current owner of one of the patents at issue, filed counterclaims alleging that CME and CBOT infringe, induce or contribute to the infringement and willfully infringe its patent. Technology Research is seeking an
injunction and damages no less than a reasonable royalty. Trial was originally set for June 2011. The matter has been dismissed with right to reinstate pending the outcome of a re-examination of the patents at issue by the USPTO. Based on its
investigation to date and advice from legal counsel, the company believes this suit is without merit and intends to defend itself vigorously against these charges.

 In 2009, Realtime Data LLC filed a complaint against CME Group and other exchanges alleging willful infringement of four patents which was later amended to add CBOT and NYMEX as

defendants. Subsequently, two additional lawsuits have been filed each adding a claim for the infringement of an additional patent. One of these lawsuits has been consolidated with the original
action and the other is under consideration for consolidation. Realtime Data is seeking a permanent injunction, unquantified enhanced damages, attorneys’ fees and costs. Discovery in this matter has not commenced. Trial is set for 2012. Based
on its investigation to date and advice from legal counsel, the company believes this suit is without merit and intends to defend itself vigorously against these charges.

 The foregoing legal matters involve alleged infringements of intellectual property, which due to their nature involve potential liability that is uncertain, difficult to quantify and involve a wide range
of potential outcomes. The company believes that the matters are without merit and intends to defend itself vigorously against the claims. We expect the re-examinations by the USPTO in the Fifth Market and Garber matters to result in a determination
of the validity of the patents at issue which we expect will have an impact on the merits of the matters. Given the uncertainty of the potential outcome of the re-examinations, at this time the company is unable to estimate the reasonably possible
loss or range of reasonably possible loss in the unlikely event it were found to be liable at trial in these matters. In the Realtime matter, no estimate of our reasonably possible loss or range of reasonably possible loss may be made at this time
because the damages sought in the proceeding have not been quantified or substantiated and the discovery phase of the matter has not commenced.

In your disclosures you have stated that your contingency matters will not have a material adverse affect on your consolidated financial position
or results of operations. It is unclear whether the phrase “material adverse” represents a higher threshold than the term “material”. Please revise this language in future filings to ensure your disclosures provide information in
the context of that which is material to your financial statements, rather than any variation thereof. Please provide us the disclosure you will include in future Exchange Act periodic reports to address this issue.

Response: The Company will include the following revised disclosure in future quarterly filings:

In addition, the company is a defendant in, and has potential for, various other legal proceedings arising from its regular business
activities. While the ultimate results of such proceedings against the company cannot be predicted with certainty, the company believes that the resolution of any of these matters on an individual basis or in the aggregate will not have a material
impact on its consolidated financial position or results of operations.

 Note 5. Contingencies, page 14

We note that you have used the phrase “estimated potential damages” in your revised disclosures within your March 31, 2011 10-Q. This
language is not contemplated by Topic 450 of the Financial Accounting Standards Codification. Please revise your disclosures in future filings to use the phrase “reasonably possible loss”.

Response: The Company will revise future filings to use the phrase “reasonably possible loss” in its contingencies disclosures.

 Acknowledgement

 In connection with the Company’s response to the Staff’s comments, the Company hereby acknowledges that:

•

 The Company is responsible for the adequacy and accuracy of the disclosure in its filings;

•

 Staff comments or changes to disclosure in response to Staff comments do not foreclose the Commission from taking any action with respect to the
filing; and

•

 The Company may not assert Staff comments as a defense in any proceeding initiated by the Commission or any person under the federal securities laws of
the United States.

 If the Staff has any questions, concerns or additional comments regarding the foregoing, please contact
me at (312) 930-3488 (phone) or (312) 930-4556 (fax).

Sincerely,

Kathleen M. Cronin

Managing Director, General Counsel and Corporate Secretary

June 9, 2011
 Mr. James E. Parisi Chief Financial Officer CME Group, Inc. 20 South Wacker Drive Chicago, Illinois 60606
Re: CME Group, Inc.
Form 10-K for the year ended December 31, 2010 Filed February 28, 2011 File No. 001-31553

Dear Mr. James E. Parisi:
We have reviewed your response letter dated April 28, 2011 and have the following
comments.  In our comments, we may ask you to provide us with information so we may better
understand your disclosure.
 Please respond to this letter within te n business days by providing the requested
information or by advising us when you will provide the requested response. If you do not believe our comments apply to your facts and circum stances, please tell us why in your response.
 After reviewing the information you provide in response to these comments, we may
have additional comments.
FORM 10-K FOR THE YEAR ENDED DECEMBER 31, 2010

 Financial Statements and Notes

 Note 18 – Contingencies, page 96

 1. We have considered your response to comment three.   Further to our previous comment,
for any contingencies where you are unable to  estimate a range of reasonably possible
losses, please explain the procedures you unde rtake on a quarterly basis to attempt to
develop a range of reasonably possible loss for di sclosure.    In addition, to the extent the
plaintiff has requested in public filings, a quantified amount please explain why a range
of reasonably possible loss cannot  be determined.  For cases that have been outstanding
for several years we would expect that at so me point you would be able to come up with
a range of possible loss (i.e., Fi fth Market and Real Time).

James E. Parisi
CME Group, Inc. June 9, 2011 Page 2

2. In your disclosures you have stated that your co ntingency matters will not have a material
adverse affect on your consolidated financial po sition or results of operations.    It is
unclear whether the phrase “material adverse” re presents a higher threshold than the term
“material”.   Please revise this language in  future filings to ensure your disclosures
provide information in the context of that wh ich is material to your financial statements,
rather than any variation thereo f.   Please provide us the disclosure you will include in
future Exchange Act periodic re ports to addres s this issue.

FORM 10-Q FOR THE PERI OD ENDED MARCH 31, 2011

 Note 5 – Contingencies, page 14

 3. We note that you have used the phrase “esti mated potential damages” in your revised
disclosures within your Marc h 31, 2011 10-Q.   This language is not contemplated by
Topic 450 of the Financial Accounting Standa rds Codification.    Please revise your
disclosures in future filings to use the phrase “reasonably possible loss”.

We urge all persons who are responsible for th e accuracy and adequacy of the disclosure
in the filing to be certain that the filing include s the information the Securities Exchange Act of
1934 and all applicable Exchange Act rules requir e. Since the company and its management are
in possession of all facts relating to a company’s disclosure, they are responsible for the accuracy
and adequacy of the disclosures they have made.
 You may contact Wilson K. Lee, at (202) 551-3468 or me, at (202) 551-3486 if you have
any questions.
Sincerely,

 Daniel L. Gordon  Branch Chief

CORRESP
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filename1.htm

Correspondence

 April 28, 2011

 Via EDGAR

 Division of Corporate Finance

United States Securities and Exchange Commission

100 F Street, NE

 Washington, D.C. 20549-6010

Attention:

Daniel L. Gordon, Branch Chief

Kristi Marrone

RE:

CME Group Inc. Form 10-K for the fiscal year ended December 31, 2010, filed February 28, 2011, File No. 001-31553

Dear Mr. Gordon:

 CME Group Inc. (the
“Company”) has received the comments from the staff of the Division of Corporation Finance (the “Staff”) of the Securities and Exchange Commission (the “Commission”) contained in your letter, dated March 31, 2011,
regarding the Commission’s review of the above-referenced Company filing (the “Comment Letter”). The Company hereby submits its response to the Staff’s comments contained in the Comment Letter, as set forth below. For the
convenience of the Staff, each of the Staff’s comments has been reproduced below and is set forth in bold and italics immediately prior to the Company’s response.

 Note 6. Performance Bonds and Guaranty Fund Contributions, page 81

 In
future filings please expand your disclosure to address why certain performance bonds, guaranty fund contributions, cross-margin arrangements and performance collateral for delivery have been included on your balance sheet, while other performance
bonds and performance collateral for delivery, non-cash deposits and IEF funds have not been included. Please provide us with your proposed disclosure, addressing whether 1) you have risks and rewards associated with ownership of the collateral, 2)
the funds are held by you, 3) the funds are available for your use and 4) if you receive interest income from the deposits.

Response: Currently, the Company discloses the following in Footnote 1, Summary of Significant Policies in our Form 10-K for the year ended
December 31, 2010:

 Performance Bonds and Guaranty Fund Contributions. Performance bonds and guaranty fund
contributions held by the exchange for clearing firms may be in the form of cash, securities, deposits in one of the Interest Earning Facilities (IEFs) or other non-cash deposits. Cash performance bonds and guaranty fund contributions are reflected
in the consolidated balance sheets. Cash received may be invested by CME. These investments are typically overnight transactions in U.S. Government securities acquired through and held by a broker-dealer subsidiary of a bank or through CME’s
IEF program.

Any interest earned on these investments accrues to CME and is included in investment income in the consolidated statements of income.

Securities deposited by clearing firms include short-term U.S. Treasury and U.S. Government agency securities and are not reflected in the
accompanying consolidated balance sheets. These securities are held in safekeeping. Interest and gain or loss on securities deposited to satisfy performance bond and guaranty fund requirements accrues to the clearing firm.

This disclosure will be revised as follows in the Company’s future Form 10-K filings:

Performance Bonds and Guaranty Fund Contributions. Performance bonds and guaranty fund contributions held by the exchange for
clearing firms may be in the form of cash, securities or other non-cash deposits.

 Performance bonds and guaranty fund
contributions received in the form of cash are held by CME and may be invested overnight in U.S. Government securities acquired through and held by a broker-dealer subsidiary of a bank or through CME’s IEF program. Any interest earned on these
investments accrues to CME and is included in investment income in the consolidated statements of income. Because the benefits and risks of ownership accrue to CME, cash performance bonds and guaranty fund contributions are reflected in the
consolidated balance sheets.

 Securities and other non-cash deposits may include short-term U.S. Treasury, U.S. Government
agency securities and gold bullion. Securities and other non-cash deposits are held in safekeeping by a custodian bank. Interest and gains or losses on securities deposited to satisfy performance bond and guaranty fund requirements accrue to the
clearing firm. Because the benefits and risks of ownership accrue to the clearing firm, non-cash performance bonds and guaranty fund contributions are not reflected in the consolidated balance sheets.

Note 8. Intangible Assets and Goodwill, page 84

 In future filings please expand your disclosure to describe the nature of indefinite-lived trading products. Please provide us with your proposed future disclosures.

Response: The Company will add the following disclosure regarding the nature of its indefinite-lived trading products to its Intangible Assets and
Goodwill footnote in future quarterly filings:

 Trading products represent futures and options products acquired in our
business combinations with CBOT Holdings and NYMEX Holdings. Clearing and transaction fees revenues are generated through the trading of these products. These trading products, most of which have traded for decades, require authorization from the
Commodity and Futures Trading Commission (CFTC). Product authorizations from the CFTC have no term limits.

 Note 18. Contingencies, page 96

We note that you are involved in various legal proceedings. If there is at least a reasonable possibility that a loss may be incurred as a result of
these proceedings, please disclose an estimate or range of possible loss or include a statement that such an estimate cannot be made. Refer to ASC 450-20-50-4.

 Response: The Company will reassess its disclosures of legal proceedings beginning with Form 10-Q for the quarter ended March 31, 2011. In accordance with ASC 450-20-50-4, to the extent that
losses are determined to be reasonably possible, we will disclose an estimate or range of the possible loss or a statement that such an estimate cannot be made.

 Acknowledgement

 In connection with the Company’s response to the Staff’s
comments, the Company hereby acknowledges that:

•

 The Company is responsible for the adequacy and accuracy of the disclosure in its filings;

•

 Staff comments or changes to disclosure in response to Staff comments do not foreclose the Commission from taking any action with respect to the
filing; and

•

 The Company may not assert Staff comments as a defense in any proceeding initiated by the Commission or any person under the federal securities laws of
the United States.

 If the Staff has any questions, concerns or additional comments regarding the foregoing, please contact
me at (312) 930-3488 (phone) or (312) 930-4556 (fax).

 Sincerely,

 Kathleen M. Cronin

 Managing Director, General Counsel and

 Corporate Secretary

March 31, 2011

Mr. James E. Parisi
Chief Financial Officer
CME Group Inc.
20 South Wacker Drive
Chicago, IL  60606

Re: CME Group Inc.
 Form 10- K
Filed February 28, 2011
File No. 001 -31553
 Dear Mr. Parisi :
 We have reviewed your filing and have t he following comments.  In some of our
comments, we may ask you to provide us with information so we may better understand your disclosure.
 Please respond to this letter within ten business days by amending your filing, by
providing the requested informat ion, or by advising us when you will provide the requested
response.  If you do not believe our comments apply to your facts and circumstances or do not
believe an amendment is appropriate, please tell us why in your response.
 After reviewing any amendm ent to your filing and the information you provide in
response to these comments, we may have  additional comments.

Note 6. Performance Bonds and Guaranty Fund Contributions, page 81
 1. In future filings please expand your disclosure to address why certain performance bonds, guaranty fund contributions, cross -margin arrangements and performance collateral for
delivery have been included on your balance sheet, while other performance bonds and performance collateral for delivery, non -cash deposits  and IEF funds have not been
included.  Please provide us with your proposed disclosure, addressing whether 1) you have risks and rewards associated with ownership of the collateral, 2) the funds are held by you, 3) the funds are available for your use and 4) if you receive interest income from
the deposits.

Note 8. Intangible Assets and Goodwill, page 84

2. In future filings please expand your disclosure to describe the nature of indefinite -lived
trading products.  Please provide us with your proposed futur e disclosures.

Mr. James E. Parisi
CME Group Inc.
March 31, 2011
Page 2

Note 18. Contingencies, page 96
 3. We note that you are involved in various legal proceedings.  If there is at least a reasonable possibility that a loss may be incurred as a result of these proceedings, please disclose an estimate or range o f possible loss or include a statement that such an estimate
cannot be made.  Refer to ASC 450- 20-50-4.
 We urge all persons who are responsible for the accuracy and adequacy of the disclosure
in the filing to be certain that the filing includes the  inform ation the Securities Exchange Act of
1934 and all applicable Exchange Act rules require.  Since the company and its management are in possession of all facts relating to a company’s disclosure, they are r esponsible for the accuracy
and adequacy of the disc losures they have made.

 In responding to our comments, please provide  a written statement from the company
acknowledging that:

• the company is responsible for the adequacy and accuracy of the disclosure in the filing;

• staff comments or changes to disclosure in response to staff comments do not foreclose
the Commission from taking any action with respect to the filing; and

• the company may not assert staff comments as a defense in any proceeding initiated by
the Commission or any person under the federa l securities laws of the United States.

You may contact Kristi Marrone  at (202) 551- 3429 or me at (202) 551 -3486 if you have
questions regarding comments on the financial statements and related matters.

Sincerely,

Daniel L. Gordon
Branch Chief

CORRESP
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Correspondence

 February 28, 2011

VIA EDGAR TRANSMISSION

Securities and Exchange Commission

 450 Fifth
Street, N.W.

 Washington, D.C. 20549

Re:
Filing of CME Group Inc. Annual Report on Form 10-K for the year ended

December 31, 2010

 Ladies and
Gentlemen:

 On behalf of CME Group Inc., a Delaware corporation (the “Company”), transmitted herewith for filing is the
Company’s Annual Report on Form 10-K for the year ended December 31, 2010.

 There have not been any changes from the preceding year
in any accounting principles or practices, or in the method of applying any such principles or practices.

 If you have any questions or
comments in connection with the foregoing, please contact me at (312) 930-3305. Facsimile transmissions may be sent to the undersigned at (312) 930-4556.

Very truly yours,

 /s/ Meg Wright

Meg Wright

 Director, Associate General Counsel &

     Assistant Corporate Secretary

 1

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549-7010

       DIVISION OF
CORPORATION FINANCE

Mail Stop 3010

August 11, 2009

 VIA USMAIL and FAX (312) 930-4556  Mr. James E. Parisi  Managing Director and Ch ief Financial Officer
CME Group Inc. 20 South Wacker Drive Chicago, Illinois 60606
 Re: CME Group Inc.
Form 10-K for the fiscal year ended December 31, 2008 Filed March 2, 2009  Definitive Proxy Statement on Schedule 14A  Filed March 31, 2009 File No. 001-31553

Dear Mr. Parisi:

We have completed our review of your Fo rm 10-K and related filings and have no
further comments at this time.
Sincerely,

Tom Kluck Branch Chief

CORRESP
1
filename1.htm

Correspondence

 July 28, 2009

 Division of Corporate Finance

 United States Securities and Exchange Commission

 100 F Street, NE

 Washington, D.C. 20549-6010

 Attention: Tom Kluck, Branch Chief

                   Jerard T. Gibson, Attorney-Advisor

 RE:

 CME Group Inc. Form 10-K for the fiscal year ended December 31, 2008,

 filed March 2, 2009 and the Definitive Proxy Statement on Schedule 14A,

 filed March 31, 2009, File No.
001-31553

 Dear Mr. Kluck:

 CME Group Inc. has received the comments from the staff of the Division of Corporation Finance (the “Staff”) of the Securities and Exchange Commission (the “Commission”) contained in your follow up letter, dated
July 14, 2009, regarding the Commission’s review of the above-referenced Company filing (the “Comment Letter”). The Company hereby submits its response to the Staff’s comments contained in the Comment Letter, as set forth
below. For the convenience of the Staff, each of the Staff’s comments has been reproduced below and is set forth in bold and italics immediately prior to the Company’s response.

 Definitive Proxy Statement on Schedule 14A filed on March 31, 2009

 Compensation Discussion and Analysis

 Base Pay, page 28

1.
We note that you plan to expand your disclosure in future filings to discuss the individual factors considered by the Compensation Committee in determining annual salary
increases; however, you have not explained why Mr. Parisi received such an increase. Please provide to us in your response letter the specific factors that led to Mr. Parisi’s salary increase.

 Response: As disclosed in the Company’s 2008 Proxy Statement on page 22, the compensation committee approved an increase in Mr. Parisi’s base salary from
$325,000 to $375,000 effective as of January 1, 2008. No other salary increases were made for the named executive officers. This increase of 15% was approved in recognition of Mr. Parisi’s performance and the growth and increased
complexity of his responsibilities based on recommendations from the Chief Executive Officer and the President. This compensation level also compares favorably as compared to similar companies in our peer group. In future filings we will include
descriptions of any salary increases made in the last completed year as well as any salary increases approved for the year in which the proxy statement is filed.

 Equity Grant practices, page 33

2.
We note your response to prior comment 8 and reissue that comment. It remains unclear from your current disclosure how the pre-established formulas are derived from the
various factors discussed on page 34 under the Compensation and Discussion subheading, per your response. Please revise your disclosure to provide a more in-depth discussion of these formulas and also provide an analysis of how the formulas
contributed to the equity awards granted to the named officers in 2008.

 Response: Equity grants to named executive officers are
granted based upon a percentage of the individual’s base salary as set forth below:

 Name

Annual Equity
Award Target
as % of
Base Pay

2008
Annual Equity
Award Target

Annual Equity
Award
Maximum as %
of Base Pay

2008
Annual Equity
Award
Maximum

2008 Annual
Equity as % of
Target

2008 Annual
Equity
Award(1)

 Craig S. Donohue

300
%

$
2,550,000

345
%

$
2,932,500

100
%

$
2,549,427

 James E. Parisi

125
%

468,750

144
%

539,063

100
%

468,438

 Terrence A. Duffy

175
%

1,662,500

201
%

1,911,875

100
%

1,661,494

 Phupinder S. Gill

175
%

1,050,000

201
%

1,207,500

100
%

1,050,477

 Bryan T. Durkin

125
%

625,000

144
%

718,750

100
%

623,944

(1)
Actual value of equity awards in 2008 was calculated using the closing price on the date of the grant on June 16, 2008 of $419.41. Differences in actual values from target
values is due to rounding to the nearest five shares for vesting purposes for actual grants.

 The percentages for
deriving the equity opportunities for the named executive officers were established based upon a review of the nature of the responsibility of the position of the executive within the company, the competitive market data derived through the
company’s benchmarking practices and the ability of the employee to impact the overall growth and performance of the company based upon his or her level within the company. For example, members of the senior management group, including the
named executive officers, have greater equity opportunities than employees below such level based upon their increased level of responsibility and ability to impact our corporate performance. The company targets overall compensation in the
50th percentile of a group of companies (the peer group) with characteristics
similar to the company’s and will look at both equity compensation on a standalone basis as well as part of the executive’s overall total compensation as compared to the peer group. In 2009, in connection with the annual peer review, the
committee approved increases in the equity opportunities for Messrs. Durkin and Parisi from 125% to 175% of their base salaries for the 2010 equity awards to bring their total compensation more in line with the 50th percentile of the peer group.

 The committee has the discretion to adjust the awards in a range of 15% above or below the target opportunities listed above to distinguish for individual performance, continuing to fall well within the range of peer group companies. No
specific performance metrics are tied to the annual grant of equity. In 2008, the Chief Executive Officer and President recommended equity awards for Messrs. Parisi and Durkin at the target level. The committee approved those awards as recommended
and approved

awards for Messrs. Donohue, Duffy and Gill at the target level as well. In future filings, to the extent that the committee were to exercise discretion to
increase or decrease an award, the Company will include additional disclosure on factors considered in such discretion.

 Management Equity
Opportunities, page 34

3.
Your response to previous Comment 9 ties the established targets for your named executives to the benchmarking process, but, as currently written, your discussion of
benchmarks does not adequately provide investors with a clear understanding of how these targets are established. Please revise or advise.

 Response: Please see the above response.

 Acknowledgement

 In connection with the Company’s response to the Staff’s comments, the Company hereby acknowledges that:

•

 The Company is responsible for the adequacy and accuracy of the disclosure in its filings;

•

 Staff comments or changes to disclosure in response to Staff comments do not foreclose the Commission from taking any action with respect to the filing; and

•

 The Company may not assert Staff comments as a defense in any proceeding initiated by the Commission or any person under the federal securities laws of the United
States.

 If the Staff has any questions, concerns or additional comments regarding the foregoing, please contact me at
(312) 930-3488 (phone) or (312) 930-4556 (fax).

Sincerely,

Kathleen M. Cronin

Managing Director, General Counsel and

Corporate Secretary

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549-7010

       DIVISION OF
CORPORATION FINANCE
Mail Stop 3010

July 14, 2009
 Mr. James E. Parisi  Managing Director and Ch ief Financial Officer
CME Group Inc. 20 South Wacker Drive Chicago, Illinois 60606
 Re: CME Group Inc.
Form 10-K for the fiscal year ended December 31, 2008 Filed March 2, 2009  Definitive Proxy Statement on Schedule 14A  Filed March 31, 2009 File No. 001-31553

Dear Mr. Parisi:

We have reviewed your response in connection with the above-referenced filings
and have the following comments.  Where i ndicated, we think you should revise your
document in response to these comments.  If you disagree, we will consider your
explanation as to why our comment is inappl icable or a revision is unnecessary.  Please
be as detailed as necessary in your explanat ion.  In some of our comments, we may ask
you to provide us with information so we may better understand your disclosure.  After
reviewing this information, we may raise additional comments.
  Please understand that the purpose of our re view process is to assist you in your
compliance with the applicable disclosure  requirements and to  enhance the overall
disclosure in your filing.  We look forward to  working with you in these respects.  We
welcome any questions you may have about our  comments or any other aspect of our
review.  Feel free to call us at the telephone numbers listed at the end of this letter.

Definitive Proxy Statement on Sc hedule 14A filed on March 31, 2009

Compensation Discussion and Analysis
 Base Pay, page 28

1. We note that you plan to expand your disclo sure in future filings to discuss the
individual factors considered by the Compensation Committee in determining
annual salary increases; however, you have not explained why Mr. Parisi received

Mr. James E. Parisi
CME Group Inc. July 14, 2009 page 2

such an increase.  Please provide to us in your response letter the specific factors
that led to Mr. Parisi’s salary increase.
 Equity Grant Practices, page 33

2. We note your response to prior comment 8 and reissue that comment.  It remains
unclear from your current disclosure how the pre-established formulas are derived
from the various factors discussed on page 34 under the Compensation and
Discussion  subheading, per your response.  Plea se revise your disclosure to
provide a more in-depth discussion of thes e formulas and also provide an analysis
of how the formulas contributed to the equity awards granted to each of the
named officers in 2008.
 Management Equity Opportunities, page 34

 3. Your response to previous Comment 9 tie s the established targets for your named
executives to the benchmarking process, but, as currently written, your discussion
of benchmarks does not adequately provi de investors with a clear understanding
of how these targets are establishe d.  Please revise or advise.

*****
   As appropriate, please amend your fili ng and respond to these comments within
10 business days or tell us when you will provid e us with a response.  You may wish to
provide us with marked copies of the amendm ent to expedite our review.  Please furnish
a cover letter with your amendment that keys your responses to our comments and
provides any requested information.  Detailed co ver letters greatly faci litate our review.
Please understand that we may have addi tional comments after reviewing your
amendment and responses to our comments.    We urge all persons who are responsi ble for the accuracy an d adequacy of the
disclosure in the filing to be certain that the filing includes all in formation required under
the Securities Exchange Act of 1934 and th at they have provided all information
investors require for an informed invest ment decision.  Since the company and its
management are in possession of all facts re lating to a company’s disclosure, they are
responsible for the accuracy and adequacy of the disclosures they have made.

In connection with responding to our comments, please provide, in writing, a
statement from the company acknowledging that:  ‚ the company is responsible for the adequacy  and accuracy of the disclosure in the
filing;

Mr. James E. Parisi
CME Group Inc. July 14, 2009 page 3

‚ staff comments or changes to disclosure  in response to staff comments do not
foreclose the Commission from taking any action with respect to the filing; and
 ‚ the company may not assert staff comments as a defense in any proceeding initiated
by the Commission or any person under the federal securities laws of the United
States.

In addition, please be advise d that the Division of Enfo rcement has access to all
information you provide to the staff of the Divi sion of Corporation Fi nance in our review
of your filing or in response to our comments on your filing.     Please contact Jerard Gibson, Attorn ey-Advisor, at (202) 551-3473 or the
undersigned at (202) 551- 3473 with any questions.

Sincerely,

        T o m  K l u c k          B r a n c h  C h i e f    cc: Margaret C. Austin (via facsimile)

CORRESP
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Correspondence

 June 19, 2009

 Division of
Corporate Finance

 United States Securities and Exchange Commission

 100 F Street, NE

 Washington, D.C. 20549-6010

Attention:

Tom Kluck, Branch Chief

Jerard T. Gibson, Attorney-Advisor

RE:
CME Group Inc. Form 10-K for the fiscal year ended December 31, 2008, filed March 2, 2009 and the Definitive Proxy Statement on Schedule 14A, filed March 31, 2009,
File No. 001-31553

 Dear Mr. Kluck:

 CME Group Inc. has received the comments from the staff of the Division of Corporation Finance (the “Staff”) of the Securities and Exchange Commission (the “Commission”) contained in your letter, dated May 5, 2009,
regarding the Commission’s review of the above-referenced Company filing (the “Comment Letter”). The Company hereby submits its response to the Staff’s comment contained in the Comment Letter, as set forth below. For the
convenience of the Staff, each of the Staff’s comments has been reproduced below and is set forth in bold and italics immediately prior to the Company’s response.

 Form 10-K for the fiscal year ended December 31, 2008

Item 5.
Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities

 Dividends, page 42

1.
In future filings, please provide more detailed disclosure regarding the provisions of your existing credit facility which materially limit your ability to pay dividends or
advise us why such revision is not necessary. Refer to Item 201(c)(1) of Regulation S-K.

 Response: We note the Staff’s
comment and the Company’s future filings will contain more detailed disclosure regarding the provisions of any of our existing credit facilities and/or indentures which materially limit our ability to pay dividends. The following disclosure was
included in the Company’s Quarterly Report for the quarter ended March 31, 2009 filed with the Commission on May 8, 2009 (the “Quarterly Report”):

 Page 31:

 The indentures governing our floating and fixed rate notes, our 364-day credit facility for
$600.0 million and our revolving credit and term loan agreement for $1.4 billion due 2011 do not contain specific covenants that restrict the ability to pay dividends. These documents, however, do contain other customary financial and operating
covenants that place restrictions on the operations of the company, which could indirectly affect the ability to pay dividends.

 For example, under our revolving credit and term loan agreement, we are required to remain in compliance
with a consolidated net worth test, defined as our consolidated shareholders’ equity as of June 30, 2008 on a pro forma basis to give effect to the NYMEX Holdings merger and to give effect to the share repurchases made and special
dividends paid, but only up to the amount of such repurchases and dividends publicly announced and made or paid within 18 months after August 22, 2008 (and in no event greater than $1.5 billion in the aggregate for such repurchases and
dividends), multiplied by 0.65.

 In addition, our 364-day credit facility contains a requirement that CME remain in compliance with a
consolidated tangible net worth test, defined as consolidated shareholders’ equity less intangible assets (as defined in the agreement), of not less than $96.0 million. In the event CME elects to increase the facility, the minimum consolidated
tangible net worth test will increase ratably up to $120.0 million. CME Group, as a holding company, has no operations of its own. Instead, it relies on dividends declared and paid to it by its subsidiaries, including CME, in order to provide a
portion of the funds which it uses to pay dividends to its shareholders.

 CME Group and its subsidiaries are also required to comply with
restrictions contained in the General Corporation Laws of its state of incorporation which could also limit its (or their) ability to declare and pay dividends. The decision to pay dividends is also subject to the discretion of each entity’s
board of directors.

Item 7.
Management’s Discussion and Analysis of Financial Condition and Results of Operations

 Results of Operations, page 55

2.
Please expand this section to discuss known material trends and uncertainties that will have, or are reasonably likely to have, material impact on your revenues or income in
any material way. For example, we note your disclosure on page 6 of the business section regarding the decline of open interest of CME and CBOT during 2008 and the risk factor on page 32 regarding the decrease in trading volume of Eurodollar options
contracts in 2008. We also note your disclosure in the MD&A section on pages 48 and 56-59 that discusses the decrease in trading volume for certain products in 2008. In future filings, please revise your MD&A discussion to address this trend
and the resulting impact on revenues and operating income, or tell us why you believe it is not a material trend. Refer to Item 303 (a)(3)(i) and (ii) of Regulation S-K.

 Response: We note the Staff’s comments and will include disclosure in future filings that discusses known material
trends and uncertainties that will have, or that are reasonably likely to have, a material impact on our revenues or income. Our Quarterly Report contained the following disclosure regarding the impact of the current credit crisis on the volume of
our interest rate products:

 Page 24:

 Interest Rate Products

 In the first quarter of 2009, the global credit crisis and the Federal Reserve Bank’s zero
interest rate policy for short term interest rates were the primary contributors to the overall decrease in interest rate volume. We believe the credit crisis has led to increased risk aversion, distorted historical relationships within the interest
rate markets and reduced debt issuance. As long as these conditions are present and in the absence of offsetting events and circumstances, we expect to continue to see lower interest rate trading volume in 2009 when compared with 2008.

Operating Revenues, page 56

3.
Please note that you should disclose in quantitative terms the extent to which changes in revenues from one period to the next were attributable to changes in prices as
opposed to changes in volume. Please ensure that you address these matters in future filings. Refer to Item 303 (a)(3)(iii) of Regulation S-K.

 Response: We note the Staff’s comments and will include additional disclosure in future filings that discuss the extent to which changes in revenues were attributable to changes in prices as opposed to changes in
volume.

 The following disclosure was included in the Quarterly Report:

 Page 26:

 Volume/Rate Analysis

 Average rate per contract is impacted by our rate structure, which includes volume-based incentives; product mix; trading venue, and the percentage of
trading volume executed by customers who are members compared with non-member customers. Due to the relationship between average rate per contract and volume, the change in revenue attributable to changes in each is only an approximation. Using the
total volume and average rate per contract data provided in the table above, we estimate that clearing and transactions fees revenues increased by $169.5 million due to the increase in average rate per contract and decreased by $166.7 million due to
the decline in total volume, resulting in a net increase in revenues in the first quarter of 2009 when compared with the same period in 2008.

 Definitive Proxy Statement on Schedule 14A filed on March 31, 2009

 Corporate Governance, page 15

4.
In future filings, please disclose whether you have adopted a code of ethics that applies to your principal executive, principal financial officer, principal accounting
officer or controller, or persons performing similar functions per the requirements set forth in Item 406 (a) or Regulation S-K.

 Response: We note the Staff’s comment and will include disclosure in the proxy statement clarifying that our Code of Conduct applies to all of our employees, including our Chief Executive Officer, Chief Financial Officer, Chief
Accounting Officer and other senior financial officers.

 Compensation Discussion and Analysis

 Overview, page 24

5.
Please be advised that the Compensation Discussion and Analysis should be sufficiently precise to identify material differences in compensation policies with respect to
individual executive officers. For instance, we note that there are appreciable differences between the levels of compensation (e.g. base salary and non-equity incentive plan compensation) received by your named executives. In future filings, please
explain the reasons for the differences in the amounts of compensation awarded to the named executive officers.

 Response: We note the Staff’s comment. The differences between the allocation of compensation of our Chief Executive Officer and the other named executive officers are primarily the result of the differences in the responsibilities of
such officers and are also influenced by the results of our benchmarking practices. The Company has not adopted a policy whereby the compensation of the Chief Executive Officer or any other named executive officer must be a certain multiple higher
or lower than any of the other named executive officers. As discussed in the Compensation Discussion & Analysis section on page 36, the Company broadly targets total compensation levels at the median (50th percentile) of the market. Differences in the compensation levels for the named executive officers is based on the
role and responsibilities of the individual within the organization, level of competitive demand for the individual’s talent in the industry and the results of the Company’s benchmarking studies for similarly situated positions in the
marketplace. In future filings, the Company will include additional disclosure consistent with the foregoing.

 Base Pay, page 28

6.
We note that individual base salaries are intended to be appropriate in light of the nature and responsibility of the respective positions. In future filings, please include
the specific individual factors that the compensation committee considered in determining annual salary increases. For instance, we note on page 42 that Mr. Parisi received an increase in salary while the others executives’ salaries
remained unchanged. Refer to Item 402 (b)(2)(v) of Regulation S-K. Please tell us how you intend to comply.

 Response: We note the Staff’s comments. The Company undertakes to include additional disclosure in future filings of
the factors considered by the compensation committee in approving any future salary increases for any of our named executive officers.

 Bonus,
page 29

7.
We note your reference to a pre-determined cash earnings target of $912 million that was used to determine the cash bonus amounts payable to your named executive officers;
however, it is not clear from disclosure what specific goals for each named executive officer required achievement in order to receive the bonus payment. In future filings, please include the analysis used by the committee to determine each
executive’s individual performance of the pre-established objectives. We also note the additional metric of anticipated synergy targets resulting from your completed mergers, which was considered in connection with the bonus payment. Also,
include the pre-determined merger-related milestones for the year and explain whether each of the named executive officers had different synergy savings targets as part of such officer’s performance evaluation. Refer to Item 402 (b)(2)(v)
and Instruction 4 to Item 402 (b) and Item 302 (b)(2)(vii) of Regulation S-K. Please tell us how you intend to comply.

 Response: We note the Staff’s comment and undertake to provide enhanced disclosure in future filings. As described on page 31 of the proxy statement, in 2008, individual performance influenced approximately 30% of the annual bonus
awards for our senior management group. Performance initiatives and goals for the senior management group are approved by the board of directors on an annual basis. The senior management group is responsible for achieving these goals. For the
Management Team, including the CEO and the President, the goals are designed overall to grow the business and create value for our shareholders.

 The
following is a general summary of the 2008 goals for the Management Team:

•

 Globalize the business by generating growth in each of the following regions: Europe, Middle East, Africa, Asia and Latin America.

•

 Serve the over-the-counter markets through the extension of the Company’s reach by developing and providing over-the-counter products and services, leveraging
existing initiatives and developing other opportunities through acquisitions or strategic partnerships.

•

 Grow the core business by accelerating growth in each of the Company’s existing product lines: interest rates, foreign exchange, commodities and equities.

 For the Executive Chairman, the goals are tailored to his specific role of leading our board of directors, ensuring its effective
operation and serving as a valuable representative of the Company with our investors and regulators. For example, Mr. Duffy is responsible for ensuring effective communication amongst the board and the senior management group, participating in
key strategic discussions and decision making, such as the NYMEX Holdings transaction and participating in investor conferences, providing testimony and other education to members of the government and regulatory organizations.

 As described in the proxy statement, the performance of the Executive Chairman, CEO and President are reviewed on an annual basis at the board level with the Executive
Chairman being reviewed by the entire board during an executive session and the CEO and the

President being reviewed by the executive committee. The performance of the other named executive officers is evaluated by the CEO and the President. During
these reviews, the annual accomplishments of each individual are compared against the applicable goals along with the individual’s role in contributing to the overall accomplishments of the Company. The compensation committee takes into
consideration these performance evaluations in approving annual bonus awards. However, because the performance goals are qualitative in nature, the compensation committee has not adopted a specific formula that ties individual performance into a
specific bonus amount.

 We will also include disclosure clarifying that the synergy target was an overall target for the Company. Although different areas
of the Company were required to generate the synergies, no specific synergy milestone was included as part of the performance objective tied to the annual bonus payments for any individual named executive officer. The only requirement was that the
overall target be achieved.

 Equity Grant practices, page 33

8.
We note on page 44 under the Grants of Plan-Based Awards table that the approved 2008 equity grants were based on pre-established formulas under your equity program. In future
filings, please expand your disclosure to include such formulas or, alternatively, explain why you believe such disclosure is not material.

 Response: We note the Staff’s comment. The pre-established formulas are based upon a percentage of base pay as described in the Compensation Discussion & Analysis on page 34 of the proxy statement. In future filings, the
Grants of Plan-Based Awards table will include a reference to the disclosure contained in the CD&A for the calculation of the equity awards. The following is the disclosure that was contained in the 2009 proxy statement:

 Page 34

 In 2008, the named executive officers received the following
equity awards:

 Name

Annual Equity
Award Target
as % of
Base Pay

2008
Annual Equity
Award Target

Annual Equity
Award
Maximum as %
of Base Pay

2008
Annual Equity
Award
Maximum

2008 Annual
Equity

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549-7010

       DIVISION OF
CORPORATION FINANCE
Mail Stop 3010
        May 5, 2009  Mr. James E. Parisi  Managing Director and Ch ief Financial Officer
CME Group Inc. 20 South Wacker Drive Chicago, Illinois

Re: CME Group Inc.
 Form 10-K for the fiscal year ended December 31, 2008
Filed March 2, 2009  Definitive Proxy Statement on Schedule 14A
Filed March 31, 2009
 File No. 001-31553
Dear Mr. Parisi:
 We have reviewed your above-referen ced filings and have the following
comments.  Where indicated, we think you shoul d revise your documents in response to
these comments.  If you disagree, we will consider your explanation as to why our
comment is inapplicable or a revision is unneces sary.  Please be as detailed as necessary
in your explanation.  In some of our comme nts, we may ask you to provide us with
information so we may better understand your  disclosure.  After reviewing this
information, we may raise additional comments.   Please understand that the purpose of our re view process is to assist you in your
compliance with the applicable disclosure  requirements and to  enhance the overall
disclosure in your filing.  We look forward to  working with you in these respects.  We
welcome any questions you may have about our  comments or any other aspect of our
review.  Feel free to call us at the telephone numbers listed at the end of this letter.

Form 10-K for the fiscal year ended December 31, 2008

Item 5.  Market for Registrant’s Common E quity, Related Stockholder Matters and Issuer
Purchases of Equity Securities
 Dividends, page 42

 1. In future filings, please provide more de tailed disclosure regarding the provisions
of your existing credit facility which mate rially limit your ability to pay dividends
or advise us why such revision is not necessary.  Refer to Item 201(c)(1) of
Regulation S-K.

James E. Parisi
CME Group Inc.
May 5, 2009
Page 2

Item 7.  Management’s Discussion and Analys is of Financial Condition and Results of
Operations
 Results of Operations, page 55

 2. Please expand this section to discuss known material trends and uncertainties that
will have, or are reasonably likely to have, a material impact on your revenues or income in any material way.  For example,  we note your disclosure on page 6 of
the business section regard ing the decline of open in terest of CME and CBOT
during 2008 and the risk factor on page 32 regarding the de crease in trading
volume of Eurodollar options contracts in  2008.  We also note your disclosure in
the MD&A section on pages 48 and 56-59 that  discusses the decrease in trading
volume for certain products in 2008.  In fu ture filings, please revise your MD&A
discussion to address this trend and the resulting impact on revenues and
operating income, or tell us why you believe  it is not a material trend.  Refer to
Item 303(a)(3)(i) and (ii) of Regulation S-K.

Operating Revenues, page 56

 3. Please note that you should disclose in quantitative terms the extent to which
changes in revenues from one period to th e next were attributable to changes in
prices as opposed to changes in volume.   Please ensure that you address these
matters in future filings.  Refer to Item 303(a)(3)(iii) of Regulation S-K.

Definitive Proxy Statement on Sc hedule 14A filed on March 31, 2009

Corporate Governance, page 15
4. In future filings, please disclose whether you have adopted a code of ethics that
applies to your principal executive, principal financial officer, principal
accounting officer or controll er, or persons performing similar functions per the
requirements set forth in Item  406(a) or Regulation S-K.

Compensation Discussion and Analysis
 Overview, page 24

5. Please be advised that the Compensati on Discussion and Analysis should be
sufficiently precise to identify material di fferences in compensation policies with
respect to individual executive officers . For instance, we note that there are
appreciable differences between the levels  of compensation (e.g. base salary and
non-equity incentive plan compensation)  received by your named executives. In
future filings, please explain the reasons  for the differences in the amounts of
compensation awarded to the named executive officers.

James E. Parisi
CME Group Inc.
May 5, 2009
Page 3

Base Pay, page 28
6. We note that individual base salaries are intended to be appropriate in light of the
nature and responsibility of the respective positions.  In future filings, please
include the specific individual factors that the compensation committee considered in determining annual salary increases.  For instance, we note on page
42 that Mr. Parsi received an increase in salary while the other executives’ salaries remained unchanged.  Refer to Item 402(b)(2)(v) of Regulation S-K.
Please tell us how you intend to comply.

Bonus, page 29

7. We note your reference to a pre-determ ined cash earnings target of $912 million
that was used to determine the cash  bonus amounts payable to your named
executive officers; however, it is not clea r from your disclosure what specific
goals for each named executive officer re quired achievement in order to receive
the bonus payment. In future filings, pl ease include the analysis used by the
committee to determine each executive’s individual performance of the pre-
established objectives.  We also note the additional metric of anticipated synergy
targets resulting from your complete d mergers, which was considered in
connection with the bonus payment.  Al so, include the pre-determined merger-
related milestones for the year and expl ain whether each of the named executive
officers had different syne rgy savings targets as part of such officer’s
performance evaluation.  Refer to Item 402(b)(2)(v) and Instruction 4 to Item
402(b) and Item 402(b)(2)(vii) of Regulati on S-K.  Please tell us how you intend
to comply.

Equity Grant Practices, page 33
8. We note on page 44 under the Grants of Plan-Based Awards  table that the
approved 2008 equity grants were base d on pre-established formulas under your
equity program.  In future filings, please  expand your disclosure to include such
formulas or, alternatively, explain w hy you believe such disclosure is not
material.

Senior Management Equity Opportunities, page 34
9. In future filings, please expand your disclo sure to include the specific individual
objectives that the compensation committ ee considered in determining equity
opportunities.  Please describe how the targ ets were derived and discuss in more
detail the actual performance of each executi ve relative to the targets.  Refer to
Item 402(b)(2)(vii) of Regulation S-K.  Pl ease tell us how you intend to comply.

*****

James E. Parisi
CME Group Inc.
May 5, 2009
Page 4

 As appropriate, please amend your filings  and respond to these comments within
10 business days or tell us when you will provid e us with a response.  You may wish to
provide us with marked copies of the amendm ent to expedite our review.  Please furnish
a cover letter with your amendment that keys your responses to our comments and
provides any requested information.  Detailed co ver letters greatly faci litate our review.
Please understand that we may have addi tional comments after reviewing your
amendment and responses to our comments.    We urge all persons who are responsi ble for the accuracy an d adequacy of the
disclosure in the filing to be certain that the filing includes all in formation required under
the Securities Exchange Act of 1934 and th at they have provided all information
investors require for an informed invest ment decision.  Since the company and its
management are in possession of all facts re lating to a company’s disclosure, they are
responsible for the accuracy and adequacy of the disclosures they have made.
  In connection with responding to our comments, please provide, in writing, a
statement from the company acknowledging that:  ‚ the company is responsible for the adequacy  and accuracy of the disclosure in the
filing;
‚ staff comments or changes to disclosure  in response to staff comments do not
foreclose the Commission from taking any action with respect to the filing; and

‚ the company may not assert staff comments as a defense in any proceeding initiated
by the Commission or any person under the federal securities laws of the United States.

In addition, please be advise d that the Division of Enfo rcement has access to all
information you provide to the staff of the Divi sion of Corporation Fi nance in our review
of your filing or in response to our comments on your filing.

 Please contact Jerard Gibson, Attorn ey-Advisor, at (202) 551-3473 or the
undersigned with any questions.
Sincerely,

Tom Kluck  Branch Chief
 cc: Margaret C. Austin (via facsimile)

CORRESP
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Correspondence

 May 18, 2009

 VIA
EDGAR TRANSMISSION AND FACSIMILE

 United States Securities and Exchange Commission

 Division of Corporation Finance

 100 F Street, N.E.

 Washington, D.C. 20549-6010

Attention:

Tom Kluck, Branch Chief

Jerard T. Gibson, Attorney-Advisor

RE:

CME Group Inc. Form 10-K for the fiscal year ended December 31, 2008, filed March 2, 2009 and the Definitive Proxy Statement on Schedule 14A, filed March 31, 2009, File No.
001-31553

 Dear Mr. Kluck:

 CME Group Inc. has received the comments from the staff of the Division of Corporation Finance (the “Staff”) of the Securities and Exchange Commission contained in your letter, dated May 5, 2009, regarding the
Commission’s review of the above-referenced Company filings (the “Comment Letter”). The letter requested that we either respond within 10 business days or notify you as to when we will provide a response. Unless we receive an
objection from the Staff, the Company plans to respond to the Comment Letter on or before Friday, June 19, 2009. This timing will allow the Company to review the proposed response with the Company’s Compensation Committee during its
regularly scheduled meeting on Wednesday, June 17, 2009.

 If you have any questions or if you have an objection to our timing, please contact me at
(312) 930-3305. Facsimile transmissions may be sent to the undersigned at (312) 930-4556.

 Very truly yours,

 /s/ Meg Austin

Meg Austin

Director, Associate General Counsel and Assistant Corporate Secretary

CORRESP
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Response Letter

 Skadden, Arps, Slate, Meagher & Flom LLP

 333 West Wacker Drive

 Chicago, Illinois 60606

 Tel: (312) 407-0700

 Fax: (312) 407-0411

 http://www.skadden.com

 July 21, 2008

 VIA EDGAR AND HAND DELIVERY

 Thomas Kluck

 Branch Chief

 Division of Corporation Finance

 Securities and Exchange Commission

 100 F Street, N.E.

 Washington, D.C. 20549-0303

Re:
CME Group Inc.
 Registration Statement on Form S-4
 Commission File No. 333-151577

 Dear Mr. Kluck:

 We are writing on behalf of our client, CME Group Inc. (the
“Company”), in response to the letter of the staff (the “Staff”) of the Division of Corporation Finance of the Securities and Exchange Commission (the “Commission”), dated July 7, 2008 (the
“Comment Letter”), relating to the Company’s Registration Statement on Form S-4 filed with the Commission on June 11, 2008 (the “Registration Statement”) in connection with the merger of NYMEX Holdings, Inc. with
and into CMEG NY Inc., a wholly-owned subsidiary of the Company.

 For the convenience of the Staff, the Company’s response is
set forth below following the text of the paragraph of the Comment Letter to which the response relates. Enclosed is a copy of Amendment No. 1 to the Registration Statement (“Amendment No. 1”), which is being filed via
EDGAR concurrently herewith and which has been marked to show cumulative changes from the Registration Statement as previously filed.

 Securities and Exchange Commission

 July 21, 2008

 Page 2

 General

1.
It appears that you are relying upon Rule 430C of Regulation C. Please revise to include the appropriate undertakings required by Item 512(a)(5) of Regulation S-K or advise.

Response:
The Company has revised Item 22 (Undertakings) of the Registration Statement to include the language set forth in Item 512(a)(5)(ii).

 * * * * *

 After you have had the opportunity to review the attached, please do not hesitate to contact the undersigned (312-407-0531) or Susan S. Hassan
(312-407-0527) with any questions or further comments you may have. Facsimile transmissions may be sent to us at (312) 407-0411.

Very truly yours,

/s/ Rodd M. Schreiber

 Rodd M. Schreiber

 Skadden, Arps, Slate,
Meagher & Flom LLP

cc:
Duc Dang (Securities and Exchange Commission)

Kathleen M. Cronin (CME Group Inc.)

Susan S. Hassan (Skadden, Arps, Slate, Meagher & Flom LLP)

Richard Kerschner (NYMEX Holdings, Inc.)

Howard Chatzinoff (Weil, Gotshal & Manges LLP)

Michael J. Aiello (Weil, Gotshal & Manges LLP)

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549-7010

       DIVISION OF
CORPORATION FINANCE

Mail Stop 4561
 July 7, 2008  Kathleen Cronin, General Counsel
CME Group Inc.
20 South Wacker Drive Chicago, IL 60606

Re: CME Group Inc.  Registration Statement on Form S-4
Filed June 11, 2008 File No. 333-151577

Dear Ms. Cronin:

We have conducted a limited review of  your filing and have the following
comments.    Where indicated, we think you should revise your document in response to
these comments.  If you disagree, we will consider your explanation as to why our
comment is inapplicable or a revision is unneces sary.  Please be as detailed as necessary
in your explanation.  In some of our comme nts, we may ask you to provide us with
information so we may better understand your  disclosure.  After reviewing this
information, we may raise additional comments.
Please understand that the purpose of our re view process is to assist you in your
compliance with the applicable disclosure  requirements and to  enhance the overall
disclosure in your filing.  We look forward to  working with you in these respects.  We
welcome any questions you may have about our  comments or any other aspect of our
review.  Feel free to call us at the telephone numbers listed at the end of this letter.

 Please provide us with th e information requested belo w.  In addition, please
consider disclosing this information in the prospectus where appropriate.

General

1. It appears that you are re lying upon Rule 430C of Regulation C.  Please revise
to include the appropriate undertak ings required by It em 512(a)(5) of
Regulation S-K or advise.

2. Please be advised that we have referred this filing to the Division of Trading
and Markets.  There may be further co mment upon conclusion of their review.

Kathleen Cronin, General Counsel
CME Group Inc.
July 7, 2008
Page 2

*  *  *  *

As appropriate, please amend your regist ration statement in response to these
comments.  You may wish to provide us w ith marked copies of the amendment to
expedite our review.  Please furnish a cove r letter with your amendment that keys your
responses to our comments and provides any requested information.  Detailed cover
letters greatly facilitate our review.  Please understand that we may have additional comments after reviewing your amendmen t and responses to our comments.
We urge all persons who are responsible for the accuracy and adequacy of the
disclosure in the filing to be certain that the filing includes all in formation required under
the Securities Act of 1933 and that they have  provided all information investors require
for an informed investment decision.  Since the company and its management are in possession of all facts relating to a company’ s disclosure, they are responsible for the
accuracy and adequacy of the disclosures they have made.

 Notwithstanding our comments, in the ev ent the company requests acceleration of
the effective date of the pending registration statement, it should furnish a letter, at the
time of such request , acknowledging that:

‚ should the Commission or the staff, acti ng pursuant to delegated authority,
declare the filing effective, it does not foreclose the Commission from taking any
action with respect to the filing;

‚ the action of the Commission or the staff,  acting pursuant to delegated authority,
in declaring the filing effective, does not relieve the company from its full
responsibility for the adequacy  and accuracy of the disclosure in the filing; and

‚ the company may not assert staff comment s and the declaration of effectiveness
as a defense in any proceeding initiat ed by the Commission or any person under
the federal securities laws of the United States.
  In addition, please be advi sed that the Division of En forcement has access to all
information you provide to the staff of the Di vision of Corporation Finance in connection
with our review of your filing or in response to our comments on your filing.
We will consider a written request for acceleration of the effective date of the
registration statement as conf irmation of the fact that t hose requesting acceleration are
aware of their respective re sponsibilities under the S ecurities Act of 1933 and the
Securities Exchange Act of 1934 as they rela te to the proposed public offering of the
securities specified in the above registration statement.  We will act  on the request and,
pursuant to delegated authority, grant acce leration of the effective date.

Kathleen Cronin, General Counsel
CME Group Inc.
July 7, 2008
Page 3

We direct your attention to Rules 46 0 and 461 regarding requesting acceleration
of a registration statement.  Please allow ad equate time after the filing of any amendment
for further review before submitting a request for acceleration.  Please provide this request at least two business days in a dvance of the requested effective date.
 Please contact Duc Dang at 202-551-3386 or  me at 202-551-3233 with any other
questions.

Sincerely,

Thomas Kluck Branch Chief
cc: Susan Hassan (via facsimile)

CORRESP
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Acceleration Request

 CME GROUP INC.

 20 South Wacker Drive

 Chicago, Illinois 60606

 (312) 930-1000

 July 21, 2008

 VIA EDGAR AND FACSIMILE

 Mr. Duc Dang

 Division of Corporation Finance

 Securities and Exchange Commission

 100 F. Street, N.E.

 Washington, D.C. 20549-0303

RE:
CME Group Inc.

 Registration Statement on
Form S-4 (File No. 333-151577)

 Dear Mr. Dang:

 Pursuant to Rule 461 of the Securities Act of 1933, as amended, CME Group Inc. (the “Registrant”), respectfully requests that the effective date of the Registration Statement on Form S-4 (File
No. 333-151577) filed by the Registrant on July 21, 2008, be accelerated by the Securities and Exchange Commission (the “Commission”) to July 21, 2008 at 12:00 p.m., Eastern Time, or as soon as practicable thereafter.

 The Registrant hereby acknowledges that:

•

 should the Commission or the staff, acting pursuant to delegated authority, declare the filing effective, it does not foreclose the Commission from taking any
action with respect to the filing;

•

 the action of the Commission or the staff, acting pursuant to delegated authority, in declaring the filing effective, does not relieve the Registrant from its full
responsibility for the adequacy and accuracy of the disclosure in the filing; and

•

 the Registrant may not assert staff comments and the declaration of effectiveness as a defense in any proceeding initiated by the Commission or any person under the
federal securities laws of the United States.

 The Registrant respectfully requests that it be notified of such
effectiveness by a telephone call to Susan S. Hassan of Skadden, Arps, Slate, Meagher & Flom LLP at (312) 407-0527 and that such effectiveness also be confirmed in writing.

Very truly yours,

CME GROUP INC.

By:

 /s/ Kathleen M. Cronin

Name:

Kathleen M. Cronin

Title:

Managing Director, General Counsel and Corporate Secretary

January 29, 2008

Mail Stop 4563

By U.S. Mail and facsimile to (312) 930-4556

Craig S. Donohue
Chief Executive Officer
Chicago Mercantile Exchange Holdings, Inc.
20 South Wacker Drive
Chicago, Illinois 60606

Re:  Chicago Mercantile Exchange Holdings, Inc.
Definitive 14A
Filed March 15, 2007
File No. 00-33379

Dear Mr. Donohue:

 We have completed our review of your executive compensation and related
disclosure, and we have no further comments at this time.

 Please note that the company is responsib le for the adequacy and accuracy of the
disclosure in its filing.  We  are not approving any proposed  disclosure you may have
included in your response lette r or any disclosure you include in your future filings in
response to our comments.

If you have any further questions regardi ng our review of your filing, please call
me at (202) 551-3419.

        S i n c e r e l y ,

        C h r i s t i a n  W i n d s o r
        S p e c i a l  C o u n s e l

CORRESP
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Correspondence Letter

 January 23, 2008

 VIA
EDGAR TRANSMISSION AND FACSIMILE

 Securities and Exchange Commission

 Division of Corporation Finance

 450 Fifth Street, N.W.

 Washington, D.C. 20549

 Mail Stop 4561

 Attention: Christian N. Windsor

RE:
Chicago Mercantile Exchange Holdings Inc. Definitive 14A, Filed March 15, 2007, File No. 00-33379 (the “2007 Proxy Statement”)

 Dear Mr. Windsor:

 CME Group Inc. (formerly known as Chicago
Mercantile Exchange Holdings Inc.) (the “Company”) has received the additional comment from the staff of the Division of Corporation Finance (the “Staff”) of the Securities and Exchange Commission (the “Commission”)
contained in your letter, dated January 9, 2008, regarding the Commission’s review of the above-referenced Company filing (the “Comment Letter”). The Company hereby submits its response to the Staff’s comment contained in
the Comment Letter, as set forth below. For the convenience of the Staff, each of the Staff’s comments has been reproduced below and is set forth in bold and italics immediately prior to the Company’s response.

 Benchmarking, page 27

 1.

 It appears from your response to prior comment four that the 50th
 percentile benchmark is one of the factors considered by the Committee in setting and approving compensation. Please clarify the extent to which the Committee relies upon this target for compensation
competitiveness. Also, please clarify which of the peer groups the Committee actually uses as the relevant benchmark. Finally, please identify the members of each of the peer groups. Please refer to Item 402(b)(2)(xiv) of Regulation S-K.

 Christian N. Windsor

 Securities and Exchange Commission

 Division of Corporation Finance

 January 23, 2008

 Page 2

 Response

 The Company acknowledges the Staff’s request that the Company include
additional disclosure on the Committee’s benchmarking practices in reviewing the Company’s compensation program and elements of compensation, including additional disclosure on the Committee’s reliance on benchmarking data in its goal
of targeting the 50th percentile and its use of peer group data and the associated companies within the applicable peer groups. The Company agrees to
include the requested disclosure in its future filings as they relate to the analysis of the Committee within the applicable year.

 If the Staff has
any questions, concerns or additional comments regarding the foregoing, please contact me at (312) 930-3488 (phone) or (312) 930-4556 (fax).

Sincerely,

Kathleen M. Cronin

Managing Director, General Counsel and

Corporate Secretary

CORRESP
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Correspondence

 November 12, 2007

 VIA
EDGAR TRANSMISSION AND FACSIMILE

 Securities and Exchange Commission

 Division of Corporation Finance

 450 Fifth Street, N.W.

 Washington, D.C. 20549

 Mail Stop 4561

 Attention: Christian N. Windsor

RE:

 Chicago Mercantile Exchange Holdings Inc. Definitive 14A, Filed

 March 15, 2007, File No. 00-33379 (the “2007 Proxy Statement”)

 Dear Mr. Windsor:

 CME Group Inc. (formerly known as Chicago Mercantile Exchange Holdings Inc.) (the “Company”) has received the comments from the staff of the Division of Corporation Finance (the “Staff”) of the Securities and Exchange
Commission (the “Commission”) contained in your letter, dated September 26, 2007, regarding the Commission’s review of the above-referenced Company filing (the “Comment Letter”). The Company hereby submits its responses
to the Staff’s comments contained in the Comment Letter, as set forth below. For the convenience of the Staff, each of the Staff’s comments has been reproduced below and is set forth in bold and italics immediately prior to the
Company’s response.

 Compensation Discussion and Analysis, page 22

 1. Your disclosure suggests that individual performance was a significant factor considered by the Committee in awarding cash incentive compensation and determining annual equity grants. Please disclose and
analyze how individual performance contributed to actual 2006 compensation for the named executive officers. For example, disclose the elements of individual performance, both quantitative and qualitative, and specific contributions the compensation
committee considered in its evaluation, and if applicable, how the committee weighted and factored them into specific compensation decisions. See Item 402(b)(2)(vii) and Item 402(b)(1)(v) of Regulation S-K.

 Christian N. Windsor

 Securities and Exchange Commission

 Division of Corporation Finance

 November 12, 2007

 Page 2

 Annual Cash Bonuses

 Annual cash bonuses are awarded under the Company’s Annual Incentive Plan (“AIP”). The funding of the bonus pool was based upon the achievement of cash earnings in 2006 exceeding the established target as described beginning
on page 23 of the 2007 Proxy Statement.

 As discussed on page 24, the impact of the achievement of the cash earnings target and individual performance are
weighted differently based upon the individual’s level within the organization.

 The performance measures and their approximate weighting for the
Named Executive Officers is set forth in the table below:

 Performance Measure

 Approximate Weighting of

 Performance Measure

 Corporate Performance (Cash Earnings)

70%

 Individual Performance

30%

 For the individual performance component, an individual’s key job responsibilities and strategic initiatives
for the year are agreed upon in the beginning of the year. These goals are then incorporated into the Company’s Performance Management Process (“PMP”). The Company’s PMP is designed to evaluate an individual’s performance of
their key job responsibilities and established annual initiatives. Each individual is awarded an overall performance rating ranging from 1 to 10 with 10 being the highest. The non-financial objectives for 2006 generally consisted of: generating
additional revenue by growing our options and foreign exchange business, expanding into the energy and over-the-counter markets, growing globally in Asia; reducing costs; and enhancing our capabilities by planning for succession and enhancing our
technology plan. Mr. Donohue and Mr. Gill collectively establish the performance ratings for the other members of the Management Team, including Messrs. Parisi and Davidson and Ms. Taylor. Messrs. Donohue and Gill present the
performance reviews for the Named Executive Officers and their overall performance ratings to the Compensation Committee along with bonus recommendations. In 2006, the Compensation Committee approved their recommendations without any changes.

 Christian N. Windsor

 Securities and Exchange Commission

 Division of Corporation Finance

 November 12, 2007

 Page 3

 The table below shows the payout opportunities and actual bonus payments for 2006 for the Named Executive Officers:

 Named Executive Officer

Annual
Incentive
Plan Target
as % of Base
Earnings

 Annual
Incentive
Plan Target

 ($)

 Annual
Incentive
Plan
Maximum as

 % of Base
Earnings

Annual
Incentive
Plan
Maximum

2006 Annual
Cash Bonus
as % of Base
Earnings

2006 Annual
Cash Bonus

 Craig S. Donohue

100
%

$
847,115

150
%

$
1,270,673

138
%

$
1,168,257

 James E. Parisi

75
%

$
206,250

150
%

$
412,500

140
%

$
386,375

 Phupinder S. Gill

75
%

$
450,000

150
%

$
900,000

132
%

$
791,160

 John P. Davidson III

75
%

$
381,490

150
%

$
762,981

125
%

$
635,817

 Kimberly S. Taylor

75
%

$
232,500

150
%

$
465,000

135
%

$
418,500

 The role of the Chief Executive Officer’s individual performance in setting his annual bonus is disclosed on
page 28 of the 2007 Proxy Statement. The Compensation Committee did not assign particular weights to the factors considered in setting Mr. Donohue’s bonus. The Chief Executive Officer reviews his evaluation of the performance of the
President with the Board of Directors and the Compensation Committee considers such evaluation in setting the annual bonus for the President.

 The
Company’s discussion on the process for individual performance review and its impact on compensation is set forth on page 28. Based on the Staff’s comments, the Company will supplement its disclosure in future filings to clarify the role
of individual performance, including a discussion on its PMP, on setting actual annual bonuses similar to the discussion above.

 Equity Awards

 On page 25 of the 2007 Proxy Statement, the Company states that equity awards may be increased or decreased by 15% above or below the target
opportunity based upon an individual’s performance. In 2006, the Named Executive Officers received the following equity awards:

 Named Executive Officer

Annual
Equity Award
Target as %
of Base Pay

 Annual
Equity Award
Target

 ($)

Annual
Equity Award
Maximum as
% of Base
Pay

 Annual
Equity Award
Maximum

 ($)

2006 Annual
Equity as %
of Target

2006 Annual
Equity Award
($)

 Craig S. Donohue

300
%

$
2,550,000

345
%

$
2,932,500

100
%

$
2,550,440

 James E. Parisi

125
%

$
343,750

144
%

$
395,313

114
%

$
390,800

 Phupinder S. Gill

175
%

$
1,050,000

201
%

$
1,207,500

100
%

$
1,049,410

 John P. Davidson III

125
%

$
718,750

144
%

$
826,563

104
%

$
747,472

 Kimberly S. Taylor

125
%

$
387,500

144
%

$
445,625

100
%

$
387,852

 Christian N. Windsor

 Securities and Exchange Commission

 Division of Corporation Finance

 November 12, 2007

 Page 4

 The Chief Executive Officer and the President recommended equity award values for Messrs. Parisi and Davidson and
Ms. Taylor, within the guidelines of the program (15% above or below the target equity opportunity), taking into account the individual performance of each executive. The Compensation Committee approved their recommendations without any
changes. The Compensation Committee also approved grants at 100% of target for the Chief Executive Officer and President. The Company will include additional disclosure regarding the use of any discretion to increase or decrease the equity awards
for its Named Executive Officers in its future filings.

 2. Please disclose all the terms of the necessary targets or performance objectives to be
achieved in order for your executive officers to earn their incentive compensation for 2006 or 2007. For example, although you disclose the cash earnings target on page 26, you state that the Board utilizes other additional metrics for determining
compensation under the Annual Incentive Plan. Please note that qualitative goals generally need to be presented to conform to the requirements of 402(b)(2)(v). To the extent you believe disclosure of certain performance metrics is not required
because it would result in competitive harm such that you may omit the disclosure under Instruction 4 to Item 402(b) of Regulation S-K, please provide a detailed supplemental analysis supporting your conclusion and provide appropriate
disclosure under Instruction 4. In discussing how difficult it will be for the executive how likely it will be for the registrant to achieve the target levels or other factors, revise your disclosure to provide as much detail as necessary without
providing information that poses a reasonable risk of competitive harm. Please further refer to Item 402(b)( 1 )(v and vi) of Regulation S-K.

 The Company will clarify in its future filings the specific performance metric used to establish annual bonuses for the Named Executive Officers. For example, in 2006, cash earnings was the only metric used to determine the funding of the
bonus plan. As an additional check and balance, the Compensation Committee may review other performance metrics to ensure that the cash earnings achievement accurately reflects the Company’s overall performance. In 2006, the Company reviewed
2006 actual earnings per share and return on equity. Based on this additional review, the Committee confirmed that the Company’s 2006 cash earnings was an accurate indication of the Company’s performance.

 As discussed in response to Comment No. 1, the actual individual bonus amounts are set based upon individual performance within the established bonus guidelines. As
stated in Response No. 1, we will include additional disclosure on the role of individual performance in setting the annual bonuses.

 Christian N. Windsor

 Securities and Exchange Commission

 Division of Corporation Finance

 November 12, 2007

 Page 5

 The achievement of cash earnings is the primary driver of the bonuses paid to our Named Executive Officers. We
believe that the disclosure on page 23 of the 2007 Proxy Statement discussing the increases in the cash earnings target over time provides shareholders with an understanding of how difficult it would be to meet the future cash earnings target. We
will include a similar discussion in future filings based upon the current cash earnings target.

 Additionally, in connection with the closing of its
merger in 2007 with CBOT Holdings, Inc. (“CBOT”), the Committee approved an additional performance metric for employees with the title of Managing Director and above. As discussed on page 23 of the 2007 Proxy Statement, this additional
measure will not result in increased bonuses, but to the extent the pre-established synergy targets are not met, bonuses will be decreased. The Company will include a discussion of this additional performance metric in its future filings.

 Equity, page 24

 3. In your discussion of
the distribution of equity value among eligible employees, please clarify how the target distribution of equity awards between officers and non-officers impacts awards, both target awards and any adjustments. Please refer to Item 402(b)(1)(v)
of Regulation S-K.

 The Company sets a target distribution of annual equity value of approximately 65% to officers and 35% to non-officers in
connection with its goal of having a broad based equity program in which employees at all levels participate. The target distribution is utilized in the budgeting phase to allocate funds to the program. However, the target distribution does not
impact target awards and no adjustments to individual awards are made due to this distribution. As disclosed on page 25 individual performance is the factor that would impact whether an officer receives an award at the target level. The Company will
clarify in its future filings that the 65%/35% target distribution is not a factor in the value of individual equity awards.

 Benchmarking, page 27

 4. You state on page 20 that you set compensation at the 50th percentile of competitive market data. Please further clarify how the Committee uses the benchmark data from the three distinct peer groups used to set
compensation levels. Include a discussion of where actual compensation fell in relationship to targeted parameters. To the extent actual compensation was outside the targeted range, please explain why. Please refer to Item 402(b)(1)(v) and
Item 402(b)(2)(xiv) of Regulation S-K.

 The Compensation Committee utilizes
benchmark data to ensure that the Company’s total compensation package is competitive in comparison to its peer groups. The Compensation Committee generally targets the 50th percentile of that benchmark data. However, the Committee does not mandate that our compensation package fall within a specific range of the

 Christian N. Windsor

 Securities and Exchange Commission

 Division of Corporation Finance

 November 12, 2007

 Page 6

50th percentile, such as plus or minus 15%. The Compensation
Committee within its discretion may make alterations to the entire compensation program or to a specific element of the program based on its evaluation of the benchmarking data to generally align it within the 50th percentile and/or to ensure its competitive nature. To the extent a change is made in the program, applicable disclosure would be included in the CD&A. For example, on page 27,
the Company discussed modifications made to its retirement program in part due to their review of benchmarking information and disclosed on page 43 modifications to its director compensation in part due to benchmarking.

 5. Please disclose and analyze how each compensation component and your decisions regarding these elements fit into your overall compensation objectives and their
impact regarding other elements. See Item 402(b)(1)(vi) of Regulation S-K. It is not clear whether you review each element of compensation independently or whether you consider each element collectively with the other elements of your
compensation program when establishing the various forms and levels of compensation. Please provide sufficient quantitative or qualitative disclosure as appropriate of the analyses underlying the Committee’s decision to make specific
compensation awards and how decisions regarding one type of award motivate the Committee to award or consider other forms of compensation. Explain and place in context how you considered each element of compensation and how or why determinations
with respect to one element may or may not have influenced the Committee’s decisions with respect to other allocated awards.

 The Company will
clarify the purpose for each of the Company’s compensation components by including supplemental disclosure in future filings similar to the following:

 Compensation Component

 Purpose

 Base Pay

Fixed component of pay intended to compensate the employee fairly based upon their job duties and level of responsibility.

 Bonus

Variable component of pay intended to motivate and reward the employee’s contribution to achieving the Company’s short-term/annual goals.

 Equity

Variable component of pay intended to motivate and reward the employee’s contribution to achieving the Company’s long-term objectives and to serve as a retention
mechanism.

 Benefits

Fixed component of pay intended to protect against catastrophic expenses (healthcare, disability and life insurance) and provide opportunity to save for retirement (pension and
401(k)).

 Christian N. Windsor

 Securities and Exchange Commission

 Division of Corporation Finance

 November 12, 2007

 Page 7

 Compensation Component

 Purpose

 Post-Termination Compensation (Severance and Change of Control)

Fixed component of pay intended to provide a temporary income source following an employee’s involuntary termination and in the case of a change of control to also provide for continuity
of management during that event.

 Generally, the Committee reviews the appropriateness of the current compensation programs — in aggregate or
by a specific element — as needed. For instance, through the annual review of benchmark compensati

September 26, 2007
 Mail Stop 4563
By U.S. Mail and facsimile to (312) 930-4556

 Craig S. Donohue Chief Executive Officer Chicago Mercantile Exchange Holdings, Inc. 20 South Wacker Drive  Chicago, Illinois 60606
Re:  Chicago Mercantile Exchange Holdings, Inc.
Definitive 14A
Filed March 15, 2007 File No. 00-33379
 Dear Mr. Donohue:
We have limited our review of your definitive proxy statement  to your executive
compensation and other related disclosure a nd have the following comments.  Our review
of your filing is part of the Division’s focused review of executive compensation disclosure.
Please understand that the purpose of our re view process is to assist you in your
compliance with the applicable disclosure  requirements and to  enhance the overall
disclosure in your filings.  We look forward to working with you in these respects.  We
welcome any questions you may have about our comments or any other aspect of our review.  Feel free to call me at the telephone number listed at the e nd of this letter.
  In some comments we have asked you to provide us with additional information so we may better understand your disclosure.  Pl ease do so within the time frame set forth
below.  You should comply with the remain ing comments in all future filings, as
applicable.  Please confirm in writing that you will do so and also explain to us how you
intend to comply.  Please unders tand that after ou r review of all of your responses, we
may raise additional comments.     If you disagree with any of these commen ts, we will consider your explanation as
to why our comment is inapplicable or a revisi on is unnecessary.  Please be as detailed as
necessary in your explanation.

Craig S. Donohue, CEO
Chicago Mercantile Exchange Holdings, Inc.
September 26, 2007 Page 2  Compensation Discussion and Analysis, page 22

1. Your disclosure suggests th at individual performan ce was a significant factor
considered by the Committee in awarding cash incentive compensation and determining annual equity grants.  Pleas e disclose and analyze how individual
performance contributed to actual 20 06 compensation for the named executive
officers.  For example, disclose the el ements of individual performance, both
quantitative and qualitative, and spec ific contributions  the compensation
committee considered in its evaluation, and if applicable, how the committee weighted and factored them into specific compensation decisions.    See Item 402(b)(2)(vii) and Item 402(b)(1)(v) of Regulation S-K.
2. Please disclose all the terms of the necessa ry targets or performance objectives to
be achieved in order for your executi ve officers to earn their incentive
compensation for 2006 or 2007.  For example, although you disclose the cash earnings target on page 26, you state that  the Board utilizes other additional
metrics for determining compensation under the Annual Incentive Plan.  Please note that qualitative goals generally need  to be presented to conform to the
requirements of 402(b)(2)(v).  To the exte nt you believe disclosure of certain
performance metrics is not required b ecause it would result in competitive harm
such that you may omit the disclosure under Instruction 4 to Item 402(b) of
Regulation S-K, please provide a detailed supplemental analysis supporting your conclusion and provide appropriate disclosure under Instruction 4.  In discussing
how difficult it will be for the executive or how  likely it will be for the registrant
to achieve the target levels or other fact ors, revise your disclo sure to provide as
much detail as necessary without provid ing information that poses a reasonable
risk of competitive harm.  Please furthe r refer to Item 402(b)(1)(v and vi) of
Regulation S-K.
Equity, page 24

3. In your discussion of the di stribution of equity value among eligible employees,
please clarify how the target  distribution of equity awards between officers and
non-officers impacts awards, both target awards and any adjustments.  Please
refer to Item 402(b)(1)(v ) of Regulation S-K.

Benchmarking, page 27
4. You state on page 20 that you set compensation at the 50th percentile of
competitive market data.  Please further clarify how the Committee uses the
benchmark data from the three distinct peer groups used to set compensation
levels.  Include a discussion of where act ual compensation fell in relationship to
targeted parameters.  To the extent actu al compensation was outside the targeted

Craig S. Donohue, CEO
Chicago Mercantile Exchange Holdings, Inc.
September 26, 2007 Page 3
range, please explain why.  Please refe r to Item 402(b)(1)(v) and Item
402(b)(2)(xiv) of Regulation S-K.
5. Please disclose and analyze how each compensation component and your decisions regarding these elements fit into your overall compensation objectives
and their impact regarding other elements.  See Item 402(b)(1)(vi) of Regulation S-K.  It is not clear whether you review each element of compensation independently or whether you consider each  element collectively with the other
elements of your compensation program when establishing the various forms and levels of compensation.  Please provid e sufficient quantitative or qualitative
disclosure as appropriate of the analyses underlying the Committee’s decision to make specific compensation awards and how decisions regarding one type of
award motivate the Committee to award or consider other forms of compensation.
Explain and place in context how you cons idered each element of compensation
and how or why determinations with resp ect to one element may or may not have
influenced the Committee’s decisions with respect to other allocated awards.
6. Please address the Committee’s analysis of the information contained in the total compensation profiles and how the evaluati on of this information resulted in
specific awards for the fiscal year or modifications to the manner in which you implement your compensation program.  Refer to disclosure on page 29.
 Employment Contracts and Retention Agreements, page 29

7. Please discuss how the Committee determined  that the employment contracts and
retention agreements suppor t the objectives of your compensation program.
Please refer to Item 402(b)(1 )(vi) of Regulation S-K.

Use of Outside Consultants, page 30
8. With respect to the engagement of To wers Perrin, please provide the full
disclosure required by Item 407(e)(3)(iii)  of Regulation S-K.  This includes a
description of the nature a nd scope of the consultant's assignment or the material
elements of the instructions or directions  given to the consultant with respect to
the performance of its duties under the engagement .  Please provide similar
information with relating to any other consultants who provided information used
to determine compensation.  Refer, for example, to your discussion of services
provided by Hewitt Associates.

Potential Payments Upon Termination or Change in Control, page 37
9. Please describe and explain how the Committee determined the appropriate
payment and benefit levels under the various  circumstances that trigger payments
or provision of benefits under the employm ent agreements or change of control

Craig S. Donohue, CEO
Chicago Mercantile Exchange Holdings, Inc.
September 26, 2007 Page 4
arrangements.  Also, in the Compensati on Discussion and Analysis, discuss how
these arrangements fit into your overall compensation objectives and affect the
decisions you made regardi ng other compensation elements and the rationale for
decisions made in connection with these arrangements.  To the extent the terms
resulted from negotiations or were derive d from an evaluation of similar benefits
provided by peer companies; clarify how  these factors impacted the resulting
benefits.  Refer to Item 402(j) and It em 402(b)(1)(v) of Regulation S-K.  See
paragraphs (b)(1)(v) and (j)(3) of Item 402 of Regulation S-K.
10. It appears that the seve rance arrangements made fo r executive officers who are
terminated as a result of the merger w ith CBOT do not apply to all employees.
Please provide a quantitative analysis of the paymen ts under this severance
policy.  Please refer to Item  402(j) of Regulation S-K.

Director Compensation, page 42

11. Disclose all assumptions made in the va luation of awards in the option awards
column of the table by reference to a di scussion of those assumptions in your
financial statements, footnotes to the financial statements, or discussion in
management’s discussion and analysis.  See Instruction to Regulation S-K Item
402(k), which refers to Instruction 1 to Item 402(c)(2)(v) and (vi).
12. For each director, disclose by footnote to the stock and option awards columns of
the director compensation table the grant date fair value of each equity award
computed in accordance with FAS 123R.  S ee Instruction to Regulation S-K Item
402(k)(2)(iii) and (iv).
13. Disclose the aggregate nu mber of stock awards and the aggregate number of
option awards outstanding at fiscal year end held by each of those directors, as
required in the Instruction to Item 402(k)(2)(i ii) and (iv).

 Please respond to our comments by Octobe r 26, 2007, or tell us by that time when
you will provide us with a response.

We urge all persons who are responsible for the accuracy and adequacy of the
disclosure in the filing to be certain that the filing includes all in formation required under
the Securities Exchange Act of 1934 and th at they have provided all information
investors require for an informed invest ment decision.  Since the company and its
management are in possession of all facts re lating to a company’s disclosure, they are
responsible for the accuracy and adequacy  of the disclosures they have made.
  When you respond to our comments, please provide, in writing, a statement from the company acknowledging that:

Craig S. Donohue, CEO
Chicago Mercantile Exchange Holdings, Inc. September 26, 2007 Page 5
• the company is responsible for the adequacy and accuracy of the disclosure in
the filing;

• staff comments or changes to disclo sure in response to comments do not
foreclose the Commission from taking a ny action with respect to the filing;
and
 • the company may not assert staff comme nts as a defense in any proceeding
initiated by the Commission or any pers on under the federal s ecurities laws of
the United States.

In addition, please be advise d that the Division of Enfo rcement has access to all
information you provide to the staff of the Di vision of Corporation Finance in connection
with our review of your filing or in response to comments.

Please contact me at (202) 551-3419 with any questions.

Sincerely,   Christian N. Windsor Special Counsel
 CC: Meg. Austin
Assistant Corp. Secretary

CORRESP
1
filename1.htm

Correspondence Letter

 October 12, 2007

 VIA
EDGAR TRANSMISSION AND FACSIMILE

 Securities and Exchange Commission

 Division of Corporation Finance

 450 Fifth Street, N.W.

 Washington, D.C. 20549

 Mail Stop 4561

 Attention: Christian N. Windsor

RE:
Chicago Mercantile Exchange Holdings Inc. Definitive 14A,

 Filed March 15, 2007, File No. 00-33379

 Dear Mr. Windsor:

 As discussed, CME Group Inc. (formerly known as Chicago Mercantile Exchange Holdings Inc.) (the “Company”) has received the comments from the
staff of the Division of Corporation Finance (the “Staff”) of the Securities and Exchange Commission contained in your letter, dated September 26, 2007, regarding the Commission’s review of the above-referenced Company filing
(the “Comment Letter”). As discussed, the Company will respond to the Comment Letter on or before Monday, November 11, 2007. The Company has a regularly scheduled meeting of its Compensation Committee on November 7, 2007 and a
discussion of the Comment Letter and the Company’s responses is included on the agenda for such meeting.

 If you have any questions,
please contact me at (312) 930-3305. Facsimile transmissions may be sent to the undersigned at (312) 930-4556.

Very truly yours,

Meg Austin

Director, Associate General Counsel and Assistant Corporate Secretary

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549-7010
         DIVISION OF
CORPORATION FINANCE

June 4, 2007

Mail Stop 7010

By U.S. Mail and facsimile to (312) 407-8522

Kathleen M. Cronin
Managing Director, General Couns el and Corporate Secretary
Chicago Mercantile Exchange Holdings Inc.
20 South Wacker Drive
Chicago, Illinois 60606

Re:  Chicago Mercantile Exchange Holdings Inc.
 Registration Statement on Form S-4
Filed May 25, 2007
 File No. 333-143282

Dear Ms. Cronin:

We have limited our review of your filing to those issues we have addressed in
our comments below.  Where indicated, we  think you should revise your document in
response to these comments.  If you disagree, we will consider your explanation as to
why our comment is inapplicable or a revisi on is unnecessary.  Please be as detailed as
necessary in your explanation.  In some of our comments, we may ask you to provide us
with information so we may better understand your disclosure.  Af ter reviewing this
information, we may raise additional comments.

Please understand that the purpose of our re view process is to assist you in your
compliance with the applicable disclosure  requirements and to  enhance the overall
disclosure in your filing.  We look forward to  working with you in these respects.  We
welcome any questions you may have about our comments or any other aspect of our review.  Feel free to call us at the telephone numbers listed at the end of this letter.

General

1. We note your disclosure that you intend to  vote proxies submitted for the meeting
that was originally scheduled for April 4, 2007.  It appears that the revised merger
agreement contains significantly amended te rms that materially affect the amount
and structure of the merger consideration.  In addition, this registration statement
contains significant information rega rding the competing proposal for the

Kathleen M. Cronin
Chicago Mercantile Exch ange Holdings Inc.
June 4, 2007 Page 2
acquisition of CBOT Holdings, includi ng the conclusion that the competing
proposal offered a “higher implied short-term value of the ICE proposal based on recent market prices of ICE’s common stock and CME Holdings’ Class A common stock . . . .”  Accordingly, it does not appear that shareholders for each party who submitted proxies for the meeting scheduled for April 4, 2007, had access to the material terms of the revised ag reement.  In this respect, the court’s
decision in the case citation you provided to us appears to be distinguishable from
the facts applicable here and in any respect does not implicate the federal
securities laws.  Please revise or advise.

2. We note news reports regarding an ag reement between ICE and CBOE Holdings,
Inc., regarding the CBOE exercise right possessed by members of the Chicago Board of Trade.  Please update your disclosu re to discuss this recent event and its
consequences with respect to the parties to this transaction.

Comparative Stock Price and Dividends, page 20

3. Please tell us what consideration you gave to presenting the CBOT Holdings
Equivalent Per Share data using the ex change ratio in the amended merger
agreement, as it is unclear to us that e quivalent data based on the exchange ratio
in the original merger agreement would be  meaningful to investors.  In this
regard, we note that you used the new ex change ratio in your presentation of
equivalent pro forma per share data on page 25.

Summary of Unaudited Pro Forma Condensed Combined Financial Data, page 24

4. Please revise to disclose long-term debt in accordance with In struction 2 to Item
301 of Regulation S-K.

5. We read that amounts are presented in m illions, except per share data.  However,
based on comparison with your pro forma financial statements, these amounts actually appear to be in thousa nds.  Please advise or revise.

Comparative Per Share Data, page 25

6. We read that outstanding shares are presented in millions.  However, based on comparison with CME Holdings’ and CBO T Holdings’ periodic reports, these
amounts actually appear to be in thousa nds.  This is also apparent in your
calculation of book value per share.   Please advise or revise.

Kathleen M. Cronin
Chicago Mercantile Exch ange Holdings Inc.
June 4, 2007 Page 3
Background of the Merger, page 50

7. Please clearly disclose and quantify the differences in the consideration offered pursuant to the merger agreement and the ICE offer on an aggregate and per share
basis here and at “Determinati on Regarding the ICE Proposal.”

Recommendations of CBOT Holdings’ Special Transaction Committee and Non-ER
Members Committee, page 83

8. We note your statement on page 84 that the special transaction committee of
CBOT was advised by CSC Consulting, Inc., as well as references on pages 70 and 88-89 to a report rendered by CSC.  Please revise your document to include
the information required by Item 1015(b) of Regulation M-A.  Refer to Item
14(b)(6) of Schedule 14A.  Please also pr ovide the consent of CSC Consulting, as
required by Rule 436 of Regulation C.

Certain Projections, page 89

9. We note the discussion on page 126 of L azard’s financial analyses of the ICE
proposal prepared using fina ncial projections of ICE prepared by CBOT Holdings
following conversations with ICE mana gement.  To provide CBOT Holdings
stockholders and Chicago Board of Trad e members with a better understanding of
the proposed transaction, please revise the discussion under this heading to
disclose these projections.  Please separa tely identify the information provided by
ICE’s management and that produced by CBOT.

Material U.S. Federal Income Tax C onsequences of the Merger, page 156

10. The statement that the merger will be c onsidered a reorgani zation regardless of
whether any cash received in the tender offer is properly treated as merger
consideration is unclear to us.  Please revise to clarify the meaning of your use of
“properly.”

As appropriate, please amend your registration statement in response to these
comments.  You may wish to provide us with marked copies of the amendment to expedite
our review.  Please furnish a cover letter with your amendment that keys your responses to
our comments and provides any requested information.  Detailed cover letters greatly facilitate our review.  Please understand th at we may ha ve additional comments after
reviewing your amendment and responses to our comments.

We urge all persons who are responsible for the accuracy and adequacy of the
disclosure in the filing to be  certain that the filing includes all information required under
the Securities Act of 1933 and that they have provided all informatio n investors require for

Kathleen M. Cronin
Chicago Mercantile Exch ange Holdings Inc.
June 4, 2007 Page 4
an informed investment deci sion.  Since the company and its  management are in possession
of all facts relating to a company’s disclosure , they are responsible for the accuracy and
adequacy of the disclosures they have made.

Notwithstanding our comments, in the even t the company requests acceleration of
the effective date of the pending registration st atement, it should furnish a letter, at the time
of such request, acknowledging that:

• should the Commission or the staff, acting pursuant to delegated authority, declare
the filing effective, it does not  foreclose the Commission from taking any action with
respect to the filing;

• the action of the Commission or  the staff, acting pursuant to delegated authority, in
declaring the filing effective, does not re lieve the company from its full responsibility
for the adequacy and accuracy of the disclosure in  the filing; and

• the company may not assert staff comments and the declara tion of effectiveness as a
defense in any proceeding initiated by the Commission or any person under the
federal securities laws of the United States.

In addition, please be advise d that the Divisi on of Enforcement has access to all
information you provide to the staff of the Division of Corporation Finance in connection with our review of your filing or in response to our comment s on your filing.

We will consider a written request for accel eration of the effe ctive date of the
registration statement as a confirmation of th e fact that those reque sting acceleration are
aware of their respective responsibilities under th e Securities Act of 1933 and the Securities
Exchange Act of 1934 as they  relate to the proposed pub lic offering of the securities
specified in the above registration statement.   We will act on the request and, pursuant to
delegated authority, grant acceleration of the effective date.

We direct your attention to Rules 46 0 and 461 regarding requesting acceleration
of a registration statement.  Please allow ad equate time after the filing of any amendment
for further review before submitting a request for acceleration.  Please provide this request at least two business days in a dvance of the requested effective date.

Kathleen M. Cronin
Chicago Mercantile Exch ange Holdings Inc.
June 4, 2007 Page 5
You may contact Bret Johns on, Staff Accountant, at (202) 551-3753 or Jennifer
Thompson, Senior Staff Accountant, at (202)  551-3737 if you have questions regarding
comments on the financial statements and related matters.  Please contact Matt Franker, Staff Attorney, at (202) 551-3749 or me, at  (202) 551-3767 with any other questions.

Sincerely,

Jennifer R. Hardy
Branch Chief

cc: Rodd M. Schreiber
Susan S. Hassan
Skadden, Arps, Slate, Meagher & Flom LLP
333 West Wacker Drive
Chicago, Illinois 60606

July 3, 2007
VIA FACSIMILE 312.407.8522

Rodd Schreiber, Esq.
Susan Hassan, Esq.
Skadden, Arps, Slate, Meagher & Flom LLP
333 West Wacker Drive
Chicago, IL 60606

Re:   Form 425 filing made on June 28, 2007
 Filed by Chicago Mercantile Exchange Holdings, Inc.
 File No. 001-32650

Ladies and Gentlemen:

We have reviewed your filings and have th e following comments.  If you disagree with
one or more of our comments, we will consider  your explanation as to why a comment may be
inapplicable or a revision unnecessary.  Please be as detailed as necessary in your explanation.
In some of our comments, we may ask CME to provide us with supplemental information so we may better understand your disclosure.  After re viewing this information, we may or may not
raise additional comments.

 Please understand that the purpose of our re view process is to assist you in your
compliance with the applicable disclosure requir ements and to enhance the overall disclosure in
your filings.  We look forward to working with  you in these respects.  We welcome any
questions you may have about our comments or any other aspect of our review.  Feel free to call
us at the telephone number listed  at the end of this letter.

General
1. On Slide 7 of the Proxy Materials, CME presen ts a calculation of the potential full value
of the CME and ICE offers from a CBOT Holdings security holder’s perspective.  Please advise us of the basis for CME’s projection of an additional $ 6.24 in value per CBOT
Holdings share as a result of the planned tender offer.  Speci fically address for us how the
$3.5 billion is allocated betw een CBOT Holdings security holders and CME security
holders.  In addition, plea se confirm, if true, that the te nder offer is required under CME’s
merger agreement or refrain for characteriz ing the tender offer as a component of the
transaction upon which CBOT secu rity holders will be voting.
2. On Slide 7 of the Proxy Materials, CME includes $45.72 in incremental ERP upside value in its calculation of poten tial full value.  This elemen t of CME’s calculation fails to
indicate the level of uncertainty concerning the amount of potentia l consideration that

Chicago Mercantile Exchange Holdings, Inc.
SEC Comment Letter dated July 3, 2007
Page 2
could be received as a result of the CBOT/C BOE litigation.  Please make disclosure of
this contingency in future communications.
3. Slide 13 of the Proxy Materials depicts IC E has growth opportuni ties limited only to
over-the-counter products in the commodities ma rket.  It appears that slide 13 ignores
that ICE participates fully in the futures mark et for foreign exchange and equity indices.
In addition, we are aware the Department of Justice noted that among the reasons it approved a potential business combination between CME and CBOT Holdings was that
ICE would enter into the interest rate future s market regardless of whether ICE’s bid for
CBOT Holdings was successful.  Please e xplain to us the basis upon which CME relied
to exclude ICE from growth opportunities in the interest rate, fore ign exchange, credit
and equity marketplaces.  Please confirm that any future such communications will identify ICE’s current and/or future partic ipation in all of the markets in which it
competes.

* * * * *

Closing Comments

We urge all persons who are responsible for th e accuracy and adequacy of the disclosure
in the filings reviewed by the staff to be certain that they have provided all information investors
require for an informed voting and investment decision.  Since the partic ipants are in possession
of all facts relating to their disc losure, they are responsible for the accuracy and adequacy of the
disclosures they have made.

In addition, please be advise d that the Division of Enfo rcement has access to all
information you provide to the sta ff of the Division of Corporati on Finance in our review of your
filings or in response to our comments on your filings.

Please furnish a cover letter with your amendment that ke ys your responses to our
comments and provides any requested supplemental information.  Detailed cover letters greatly
facilitate our review.  Please  electronically file your cove r letter on EDGAR.  Again, please
understand that we may have additional comments after reviewing any amen dments or responses
to our comments.  If you have any ques tions, please contact me at 202.551.3266.

Sincerely,   Nicholas P. Panos
        S p e c i a l  C o u n s e l
        Office of Mergers & Acquisitions

CORRESP
1
filename1.htm

Correspondence

 SKADDEN, ARPS, SLATE, MEAGHER &
FLOM LLP

 333 WEST WACKER DRIVE

 CHICAGO, ILLINOIS 60606-1285

 TEL: (312) 407-0700

 FAX: (312) 407-0411

 www.skadden.com

 DIRECT DIAL

 (312) 407-0531

 DIRECT FAX

 (312) 407-8522

 EMAIL ADDRESS

 RSCHREIB@SKADDEN.COM

 FIRM/AFFILIATE OFFICES

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 VIENNA

 July 5, 2007

 VIA EDGAR AND ELECTRONIC

 MAIL

 Nicholas P. Panos

 Special Counsel

 Office of Mergers & Acquisitions

 Division of Corporation Finance

 Securities and Exchange Commission

 100 F Street, N.E.

 Washington, D.C. 20549-0303

RE:
Chicago Mercantile Exchange Holdings Inc.

Form 425 Filings made on June 22, 25 and 28, 2007

File No.
001-32650

 Dear Mr. Panos:

 We are writing on behalf of our client, Chicago Mercantile Exchange Holdings Inc. (“CME”), in response to your letters, dated June 27, 2007
(the “June 27 Letter”) and July 3, 2007 (the “July 3 Letter” and, together with the June 27 Letter, the “Comment Letters”), relating to CME’s Form 425 filings made on June 22, 25, and 28, 2007 in
connection with CME’s proposed merger (the “Merger”) with CBOT Holdings, Inc. (“CBOT Holdings”).

 For your
convenience, the responses are set forth below following the text of the paragraph of the Comment Letters to which the response relates.

 Nicholas P. Panos

 July 5, 2007

 Page 2

 June 27 Letter

1.
The note contained in the slide pertaining to the implied ICE stock price references a CME implied price that has not been included on the slide. Please advise us whether this
graph inadvertently omitted to state the CME implied price. In addition, please briefly explain to us why this graph supports the belief that ICE’s stock price is no longer driven by the fundamentals. Please confirm the future presentations
will emphasize that such illustrations represent the beliefs of CME or will disclose why such observations and findings should be accepted as fact.

 Response: CME respectfully advises the Staff that the omission of the reference to the CME implied price on slide 6 of the presentation filed on June 25, 2007 was inadvertent. The note should have read
“ICE implied price is based on a 1.42 exchange ratio.” CME respectfully confirms that the correct note will be included in future presentations.

 CME respectfully advises the Staff that it believes the graph on slide 6 of the presentation filed on June 25, 2007 supports CME’s belief that ICE’s stock price is no longer driven by the fundamentals.
The graph displays recent fluctuations in ICE’s stock price that the analysts quoted on page 6 and 7 of the presentation have attributed to the expectation that ICE would not succeed in its attempt to merge with CBOT Holdings and would itself
become a takeover target. Accordingly, CME believes that the graph reflects its belief that recent increases in ICE’s stock price were based on takeover speculation rather than fundamental operating results. This belief is supported by the
comments of several analysts referenced in the presentation, including the following statements:

•

 “We believe that ICE’s stock has traded higher since the CME revised offer in expectation that ICE would not succeed in its bid attempt and would itself
become a takeover target.” Niamh Alexander and Matthew Petricone, CIBC World Markets, Equity Research Company Update on Intercontinental Exchange, p. 2 (June 13, 2007).

•

 “And while fundamentals have been decent, we are not sure they are strong enough to support the stock at current levels.” Christopher J. Allen, Bank of
America Equity Research, Heads Up! Report on Chicago Mercantile Exchange Holdings, Inc., p. 1 (June 14, 2007).

•

 “If it became evident ICE would win, ICE stock would fall substantially, perhaps to $135 or $140.” Aaron Lucchetti, The Wall Street Journal, Duel for

 Nicholas P. Panos

 July 5, 2007

 Page 3

CBOT’s Hand Goes On – Chicago Merc Sweetens Its Bid Again, but ICE Keeps Up Its Courtship, p. C3 (quoting Mike Vinciquerra, an analyst at BMO
Capital Markets).

 CME respectfully confirms that future presentations will emphasize that such illustrations represent
the beliefs of CME or will disclose why such observations and findings should be accepted as fact.

2.
Each statement or assertion of opinion or belief expressed in additional soliciting material must be characterized as such and be supported on a reasonable factual basis that is
self-evident, disclosed in the soliciting materials, or provided to the staff on a supplemental basis. We cite the following non-exhaustive examples of assertions that should be specifically supported or not used in future written communications:

On June 22, 2007:

•

 We have a long-standing pricing strategy of providing the lowest trading fees for member liquidity providers, with discounts that significantly exceed anything
offered by ICE.

On June 25, 2007, the following statements made concerning the ICE proposal:

•

 Speculative synergy projections;

•

 Value of ICE stock not trading on fundamentals;

•

 Catastrophic integration risk; and

•

 Questionable clearing and technology.

 Response: Pricing strategy. CME respectfully advises the Staff the assertion made on June 22, 2007 regarding CME’s pricing policy is supported by data contained in the current fee schedule for ICE and CME’s
current fee schedule and its fee schedules for the past five years. According to the fee schedules, ICE charges its members $0.70 per side on most of its futures contracts with no price adjustments for its members, while CME offers varying prices
for all products and offers its members the lowest prices for each product. CME’s fee schedule also shows that CME charges significantly less than $0.70 for its futures contracts.

 Nicholas P. Panos

 July 5, 2007

 Page 4

 Speculative synergy projections. CME respectfully advises the Staff that its assertion relating to the synergy projections in ICE’s proposal is supported by the following statements included in a letter to shareholders filed on
Form 425 on March 23, 2007:

•

 The $100 million of operational expense synergies ICE targets represent 43% of the total cost base of the combined company. In nine previous actual or proposed
transactions involving exchanges from 2001 through 2006, the estimated amount of cost synergies have ranged from 4% to 19% of the total cost base of the combined company, with a median rate of 10%. ICE has not explained how it expects to achieve
synergies four times higher than what others in the industry have achieved.

•

 ICE’s clearing synergy estimate of $90 million doesn’t appear to take into account the significant expenses that will be necessary to handle the increased
clearing volume. It also doesn’t account for CBOT’s standalone clearing alternatives.

 In addition, CME believes the
June 26, 2007 report of Institutional Shareholder Services (“ISS”) regarding the Merger supports its assertion. In its report on the Merger, the ISS report states that “given the higher integration and execution risk associated
with a merger with ICE, ISS believes the probability of achieving these synergies are higher with CME.”

 Value of ICE stock not
trading on fundamentals. Please see response number 1 to the June 27 Letter above.

 Catastrophic integration risk. CME
respectfully advises the Staff that the assertion made on June 25, 2007 related to the integration risk of ICE’s proposal is supported by the report of CSC Consulting, Inc. (“CSC”), the independent technology consultant retained
by the special transaction committee of CBOT Holdings to review ICE’s technology. As disclosed in the Definitive Proxy Statement filed on June 7, 2007, CSC concluded that, among other things, the 18-month timeframe for integration proposed
by ICE was not realistic. CSC also concluded that even the 24-month timeframe assumed by CBOT Holdings’ management, while possible, was aggressive and carried risks. The CSC report also highlighted the uncertainties surrounding the further
development and execution of an integration plan for the CBOT trading and clearing platforms.

 CME’s assertion is further supported by
the following statements made in the letter from CBOT Holdings to its members filed on June 27, 2007, in which CBOT

 Nicholas P. Panos

 July 5, 2007

 Page 5

 Holdings stated that
“[r]ecent history at ICE demonstrates the risk and complexity of quickly scaling a system. Since 2006, ICE has had eight platform outages that impacted its trading day and customers. We think you’ll agree that the risk to CBOT and our
customers is too great for ICE to scale its system to handle CBOT volumes while developing and testing the functionality of algorithms, options, market maker and delta option protections.”

 Questionable clearing and technology. CME respectfully advises the Staff that the assertion made on June 25, 2007 regarding questionable clearing
and technology is supported by the CSC report. As disclosed in the Definitive Proxy Statement filed on June 7, 2007, the CSC report highlighted the uncertainties surrounding the further development and execution of an integration plan for the CBOT
trading and clearing platforms. In addition, CME and CBOT Holdings stated in the Definitive Proxy Statement filed on June 7, 2007 that significant gaps exist between the current capabilities of CBOT’s trading and clearing functions, and the
existing capabilities and functionality offered by ICE and NYBOT. CME’s assertion is further supported by the fact that, since 2006, ICE has had eight platform outages that impacted its trading day and customers, as described above.

CME respectfully confirms that each statement or assertion of opinion or belief expressed in additional soliciting material will be characterized as
such and be supported on a reasonable factual basis that is self-evident, disclosed in the soliciting materials or provided to the staff on a supplemental basis.

 July 3 Letter

1.
On Slide 7 of the Proxy Materials, CME presents a calculation of the potential full value of the CME and ICE offers from a CBOT Holdings security holder’s perspective.
Please advise us of the basis for CME’s projection of an additional $6.24 in value per CBOT Holdings share as a result of the planned tender offer. Specifically address for us how the $3.5 billion is allocated between CBOT Holdings security
holders and CME security holders. In addition, please confirm, if true, that the tender offer is required under CME’s merger agreement or refrain for characterizing the tender as a component of the transaction upon which CBOT security holders
will be voting.

 Response: CME respectfully advises the Staff that the projection of an additional $6.24 per CBOT Holdings share as
a result of the planned tender offer is based on CME’s belief that it is appropriate for CBOT Holdings shareholders to consider the potential to realize the difference between the proposed tender offer price and the

 Nicholas P. Panos

 July 5, 2007

 Page 6

 trading price as of the
date of the presentation. CME respectfully refers the Staff to the footnote to slide 7, which reminds readers that the proposed tender offer is limited to $3.5 billion. CME confirms that the tender offer will be available to all shareholders of the
combined company after the Merger. CME respectfully confirms that the proposed tender offer is required to be commenced following the Merger pursuant to Section 6.18 of the merger agreement, subject to the consummation of the Merger.

2.
On Slide 7 of the Proxy Materials, CME includes $45.72 in incremental ERP upside value in its calculation of potential full value. This element of CME’s calculation fails to
indicate the level of uncertainty concerning the amount of potential consideration that could be received as a result of the CBOT/CBOE litigation. Please make disclosure of this contingency in future communications.

 Response: CME respectfully confirms that it will disclose the contingency related to the CBOT/CBOE litigation in future communications.

3.
Slide 13 of the Proxy Materials depicts ICE has growth opportunities limited only to over-the-counter products in the commodities market. It appears that slide 13 ignores that
ICE participates fully in the futures market for foreign exchange and equity indices. In addition, we are aware the Department of Justice noted that among the reasons it approved a potential business combination between CME and CBOT Holdings was
that ICE would enter into the interest rate futures market regardless of whether ICE’s bid for CBOT Holdings was successful. Please explain to us the basis upon which CME relied to exclude ICE from growth opportunities in interest rate, foreign
exchange, credit and equity marketplaces. Please confirm that any future such communications will identify ICE’s current and/or future participation in all of the markets in which it competes.

 Response: CME respectfully advises the Staff that, in excluding ICE from growth opportunities in interest rate, foreign exchange, credit and equity OTC
marketplaces, CME relied on the fact that ICE only participates in the energy OTC market and, to the knowledge of CME, has not publicly indicated plans to enter the foreign exchange or equity OTC markets. While ICE has stated that it plans to enter
the interest rate OTC market, CME believes that ICE would not have growth opportunities in the interest rate OTC market until it officially begins to participate in the related futures market.

 Nicholas P. Panos

 July 5, 2007

 Page 7

 CME also
relied on volume data from the World Federation of Exchanges that indicates only limited amounts of futures trading by ICE/NYBOT in the markets referenced in slide 13. According to this data, ICE/NYBOT’s 2006 equity index futures and options
volume accounted for less than 0.1% of the equity index futures and options volume traded in the world, representing only 0.02% of the total equity index notional value traded on the world’s exchanges in 2006. The data also indicates that
ICE/NYBOT’s 2006 foreign exchange futures and options volumes accounted for only 2.5% of the foreign exchange futures and options volume traded in the world, representing only 2.0% of the total foreign exchange notional value traded on the
world’s exchanges in 2006. CME respectfully advises the Staff of its belief that ICE’s limited amount of futures trading limits ICE’s opportunities to expand into the related OTC markets.

 CME respectfully advises the Staff that if it is determined that ICE participates or will participate in other markets, that fact will be
identified in future communications.

 * * * * *

 Nicholas P. Panos

 July 5, 2007

 Page 8

 After you
have had the opportunity to review these responses, please do not hesitate to contact the undersigned (312-407-0527) or Rodd M. Schreiber (312-407-0531) with any questions or further comments you may have. Facsimile transmissions may be sent to us
at (312) 407-0411.

 Very truly yours,

 /s/ Susan S. Hassan

 Skadden, Arps, Slate, Meagher & Flom LLP

cc:
Kathleen M. Cronin (Chicago Mercantile Exchange Holdings Inc.)

Rodd M. Schreiber (Skadden, Arps, Slate, Meagher & Flom LLP)

June 27, 2007
VIA FACSIMILE 312.407.8522

Rodd Schreiber, Esq.
Susan Hassan, Esq.
Skadden, Arps, Slate, Meagher & Flom LLP
333 West Wacker Drive
Chicago, IL 60606

Re:   Form 425 filings made on June 22 and 25, 2007
 Filed by Chicago Mercantile Exchange Holdings, Inc.
 File No. 001-32650 (Film Nos. 07939499, 07937025)

Ladies and Gentlemen:

We have reviewed your filings and have th e following comments.  If you disagree with
one or more of our comments, we will consider  your explanation as to why a comment may be
inapplicable or a revision unnecessary.  Please be as detailed as necessary in your explanation.
In some of our comments, we may ask CME to provide us with supplemental information so we may better understand your disclosure.  After re viewing this information, we may or may not
raise additional comments.

 Please understand that the purpose of our re view process is to assist you in your
compliance with the applicable disclosure requir ements and to enhance the overall disclosure in
your filings.  We look forward to working with  you in these respects.  We welcome any
questions you may have about our comments or any other aspect of our review.  Feel free to call
us at the telephone number listed  at the end of this letter.

General
1. The note contained in the slid e pertaining to the implied ICE stock price references a
CME implied price that has not been included on  the slide.  Please advise us whether this
graph inadvertently omitted to state the CME implied price.  In addition, please briefly
explain to us why this graph s upports the belief that ICE’s st ock price is no longer driven
by the fundamentals.  Please confirm that futu re such presentations will emphasize that
such illustrations represent the beliefs of CME or will disclose why such observations and findings should be accepted as fact.
2. Each statement or assertion of opinion or beli ef expressed in additi onal soliciting material
must be characterized as such and be supported on a reasonable factual basis that is self-
evident, disclosed in the soliciting material s, or provided to the staff on a supplemental
basis.  We cite the following non-exhaustiv e examples of assertions that should be
specifically supported or not used in  future written communications:

Chicago Mercantile Exchange Holdings, Inc.
SEC Comment Letter dated June 27, 2007
Page 2
 On June 22, 2007:
• We have a long-standing pricing strategy of  providing the lowest trading fees for
member liquidity providers, with discounts that significantly exceed anything offered by ICE.
On June 25, 2007, the following statements made concerning the ICE proposal:

• Speculative synergy projections;

• Value of ICE stock not trading on fundamentals;

• Catastrophic integration risk; and

• Questionable clearing and technology.

* * * * *

Closing Comments

We urge all persons who are responsible for th e accuracy and adequacy of the disclosure
in the filings reviewed by the staff to be certain that they have provided all information investors
require for an informed voting and investment decision.  Since the partic ipants are in possession
of all facts relating to their disc losure, they are responsible for the accuracy and adequacy of the
disclosures they have made.

In addition, please be advise d that the Division of Enfo rcement has access to all
information you provide to the sta ff of the Division of Corporati on Finance in our review of your
filings or in response to our comments on your filings.

Please furnish a cover letter with your amendment that ke ys your responses to our
comments and provides any requested supplemental information.  Detailed cover letters greatly
facilitate our review.  Please  electronically file your cove r letter on EDGAR.  Again, please
understand that we may have additional comments after reviewing any amen dments or responses
to our comments.  If you have any ques tions, please contact me at 202.551.3266.

Sincerely,   Nicholas P. Panos
        S p e c i a l  C o u n s e l
        Office of Mergers & Acquisitions

CORRESP
1
filename1.htm

Acceleration Request

 CHICAGO MERCANTILE EXCHANGE HOLDINGS INC.

 20 South Wacker Drive

 Chicago, Illinois 60606

 (312) 930-1000

 June 5, 2007

 VIA EDGAR AND FACSIMILE

 Jennifer R. Hardy

 Branch Chief

 Division of Corporation Finance

 Securities and Exchange Commission

 100 F. Street, N.E.

 Washington, D.C. 20549-0303

RE:
Chicago Mercantile Exchange Holdings Inc.

Registration Statement on Form S-4 (File No. 333-143282)

 Dear Ms.
Hardy:

 Pursuant to Rule 461 of the Securities Act of 1933, as amended, Chicago Mercantile Exchange Holdings Inc. (the
“Registrant”), respectfully requests that the effective date of the Registration Statement on Form S-4 (File No. 333-143282) filed by the Registrant on May 25, 2007, be accelerated by the Securities and Exchange Commission (the
“Commission”) to June 5, 2007 at 5:00 p.m., Eastern Time, or as soon as practicable thereafter.

The
Registrant hereby acknowledges that:

•

 should the Commission or the staff, acting pursuant to delegated authority, declare the filing effective, it does not foreclose the Commission from taking any
action with respect to the filing;

•

 the action of the Commission or the staff, acting pursuant to delegated authority, in declaring the filing effective, does not relieve the Registrant from its full
responsibility for the adequacy and accuracy of the disclosure in the filing; and

•

 the Registrant may not assert staff comments and the declaration of effectiveness as a defense in any proceeding initiated by the Commission or any person under the
federal securities laws of the United States.

 The Registrant respectfully requests that it be notified of such
effectiveness by a telephone call to Michael P. McGrane of Skadden, Arps, Slate, Meagher & Flom LLP at (312) 407-0808 and that such effectiveness also be confirmed in writing.

Very truly yours,

CHICAGO MERCANTILE EXCHANGE HOLDINGS INC.

By:

/s/ Kathleen M. Cronin

Name:

Kathleen M. Cronin

Title:

 Managing Director, General Counsel and

 Corporate
Secretary

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549-7010

       DIVISION OF
CORPORATION FINANCE

Mail Stop 7010
        A p r i l  6 ,  2 0 0 7

James E. Parisi
Chief Financial Officer
Chicago Mercantile Exchange Holdings, Inc.
20 South Wacker Drive
Chicago, Illinois 60606

Re: Chicago Mercantile Exchange Holdings, Inc.
Form 10-K for Fiscal Year Ended December 31, 2006
Filed March 1, 2007
  File No. 0-33379

Dear Mr. Parisi:

We have completed our review of your Fo rm 10-K and related filings and have no
further comments at this time.

If you have any further questions regard ing our review of your filings, please
direct them to Bret Johnson, Staff Accountant, at (202) 551-3753 or, in his absence, to
the undersigned at (202) 551-3768.

        S i n c e r e l y ,

        John Cash
        A c c o u n t i n g  B r a n c h  C h i e f

CORRESP
1
filename1.htm

Correspondence Letter

 April 5, 2007

 VIA EDGAR
TRANSMISSION AND FACSIMILE

 Securities and Exchange Commission

 Division of Corporate Finance

 450 Fifth Street, N.W.

 Washington, D.C. 20549

 Mail Stop 4561

Attention:

John Cash

Bret Johnson

Jennifer Thompson

RE:

Chicago Mercantile Exchange Holdings Inc.

Form 10-K for the year ended December 31, 2006

Filed March 1, 2007

File No. 000-33379

 Ladies and Gentlemen:

 Chicago Mercantile Exchange Holdings Inc. (the “Company”) has received and reviewed the comments from the staff of the Division of Corporate Finance (the “Staff”) of the Securities and Exchange
Commission (the “Commission”) contained in a letter from John Cash, Accounting Branch Chief, dated March 26, 2007, regarding the Commission’s review of the above-referenced Company filing (the “Comment Letter”). The
Company hereby submits its responses to the Staff’s comments contained in the Comment Letter, as set forth below. For the convenience of the Staff, each of the Staff’s comments has been reproduced below and is set forth in italics
immediately prior to the Company’s response.

 Securities and Exchange Commission

 April 5, 2007

 Page 2

 FORM 10-K FOR
FISCAL YEAR ENDED DECEMBER 31, 2006

 Controls and Procedures, page 98

1.
We note that your Chief Executive Officer and Chief Financial Officer concluded the Company’s disclosure controls and procedures “. . .are effective in recording,
processing, summarizing, and reporting, on a timely basis, information required to be disclosed by us in the reports that we file or submit under the Exchange Act.” In future filings, please revise your disclosure to clarify, if true, that your
officers also concluded that your disclosure controls and procedures are effective to ensure that information required to be disclosed by an issuer in the reports that it files or submits under the Exchange Act is accumulated and communicated to
your management, including its principal executive and principal financial officers, or persons performing similar functions, as appropriate to allow timely decisions regarding required disclosure. Alternatively, your officers may conclude that the
Company’s disclosure controls and procedures are “effective” without defining disclosure controls and procedures.

 Response: We note the Staff’s comment and the disclosure in Item 4 of future Forms 10-Q and Item 9A of future Forms 10-K will reflect the Staff’s comments, reading as follows (assuming the controls are determined
to be effective):

 “(a) Disclosure Controls and Procedures. The Company’s management, with the participation of the Company’s
Chief Executive Officer and Chief Financial Officer, has evaluated the effectiveness of the Company’s disclosure controls and procedures (as such term is defined in Rules13a-15(e) and 15d-15(e) under the Securities Exchange Act of 1934, as
amended (the “Exchange Act”)) as of the end of the period covered by this report. Based on such evaluation, the Company’s Chief Executive Officer and Chief Financial Officer have concluded that, as of the end of such period, the
Company’s disclosure controls and procedures are effective.”

 Exhibits 13.1 and 31.2

2.
In future filings, please ensure the wording of your Section 302 certifications is exactly as set forth in Item 601(31) of Regulation S-K, including the following:

•

 Delete the officers’ title in the first line as they are signing the certification in a personal capacity.

•

 Replace “annual report” with “report.”

 Response: We note the Staff’s comment and Section 302 certifications for future Forms 10-Q and Forms 10-K will conform exactly as set forth in Item 601(31) of Regulation S-K, including the
deletion of the officers’ title and using “report” rather than “annual report” or “quarterly report.”

 Securities and Exchange Commission

 April 5, 2007

 Page 3

 Acknowledgement

 In connection with the Company’s response to the Staff’s comments, the Company hereby acknowledges that:

•

 The Company is responsible for the adequacy and accuracy of the disclosure in its filings;

•

 Staff comments or changes to disclosure in response to Staff comments do not foreclose the Commission from taking any action with respect to the filing; and

•

 The Company may not assert Staff comments as a defense in any proceeding initiated by the Commission or any person under the federal securities laws of the United
States.

 If the Staff has any questions, concerns or additional comments regarding the foregoing, please contact me at
(312) 930-3488 (phone) or (312) 930-4556 (fax).

Very truly yours,

CHICAGO MERCANTILE EXCHANGE HOLDINGS INC.

Name:

Kathleen M. Cronin

Title:

Managing Director, General Counsel and Corporate Secretary

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549-7010

       DIVISION OF
CORPORATION FINANCE

Mail Stop 7010
        March 26, 2007

James E. Parisi
Chief Financial Officer
Chicago Mercantile Exchange Holdings, Inc.
20 South Wacker Drive
Chicago, Illinois 60606

Re: Chicago Mercantile Exchange Holdings, Inc.
Form 10-K for Fiscal Year Ended December 31, 2006
Filed March 1, 2007
  File No. 0-33379

Dear Mr. Parisi:

We have reviewed your filing and have the following comments.  Where
indicated, we think you should re vise your document in response to these comments.  If
you disagree, we will consider your explanation as to why our comment is inapplicable or
a revision is unnecessary.  Please be as deta iled as necessary in your explanation.  In
some of our comments, we may ask you to provi de us with information so we may better
understand your disclosure.  After reviewing th is information, we may raise additional
comments.

 Please understand that the purpose of our re view process is to assist you in your
compliance with the applicable disclosure  requirements and to  enhance the overall
disclosure in your filing.  We look forward to  working with you in these respects.  We
welcome any questions you may have about our comments or any other aspect of our
review.  Feel free to call us at the telephone numbers listed at the end of this letter.

FORM 10-K FOR FISCAL YE AR ENDED DECEMBER 31, 2006

Controls and Procedures, page 98

1.  We note that your Chief Executive Officer  and Chief Financial Officer concluded
the Company’s disclosure controls and pr ocedures “…are eff ective in recording,
processing, summarizing, and reporting, on a ti mely basis, information required to
be disclosed by us in the reports that we  file or submit under the Exchange Act.”
In future filings, please revise your disclosu re to clarify, if tr ue, that your officers
also concluded that your di sclosure controls and pro cedures are effective to

James Parisi
Chicago Mercantile Exchange Holdings, Inc.
March 26, 2007
Page 2
ensure that information required to be disc losed by an issuer in the reports that it
files or submits under the Exchange Act is accumulated and communicated to
your management, including its principa l executive and principal financial
officers, or persons performing similar f unctions, as appropriate to allow timely
decisions regarding required disclosure.  Alternatively, your officers may conclude that the Company's disclosure controls and proce dures are “effective”
without defining disclosure controls and procedures.

Exhibits 31.1 and 31.2

2.  In future filings, please ensure the wo rding of your Section 302 certifications is
exactly as set forth in Item 601(31) of Regulation S-K, including the following:
• Delete the officers’ title in the first line as they are signi ng the certification
in a personal capacity.
• Replace “annual report” with “report.”

Please respond to these comments within  10 business days or tell us when you
will provide us with a response.  Please furnish a letter that keys your responses to our comments and provides any requested information.  Detailed letters greatly facilitate our
review.  Please understand that we may have  additional comments after reviewing your
responses to our comments.

 We urge all persons who are responsible for the accuracy and adequacy of the disclosure in the filing to be certain that the filing includes all in formation required under
the Securities Exchange Act of 1934 and th at they have provided all information
investors require for an informed invest ment decision.  Since the company and its
management are in possession of all facts re lating to a company’s disclosure, they are
responsible for the accuracy and adequacy of the disclosures they have made.

 In connection with responding to our comments, please provide, in writing, a statement from the company acknowledging that:

• the company is responsible for the adequacy and accuracy of the disclosure in the filing;

• staff comments or changes to disclosure  in response to staff comments do not
foreclose the Commission from taking a ny action with respect to the filing;
and

• the company may not assert staff comme nts as a defense in any proceeding
initiated by the Commission or any pers on under the federal securities laws of
the United States.

James Parisi
Chicago Mercantile Exchange Holdings, Inc.
March 26, 2007
Page 3
In addition, please be advise d that the Division of Enfo rcement has access to all
information you provide to the staff of the Divi sion of Corporation Fi nance in our review
of your filing or in response to our comments on your filing.

 You may contact Bret Johnson at (2 02) 551-3753, Jennifer Thompson at (202)
551-3737, or me at (202) 551-3768 if you have  questions regard ing our comments.

Sincerely,

John Cash
Accounting Branch Chief

CORRESP
1
filename1.htm

SEC Correspondence

 Skadden, Arps, Slate, Meagher & Flom LLP

 333 West Wacker Drive

 Chicago, Illinois 60606

 Tel: (312) 407-0700

Fax: (312) 407-0411

 http://www.skadden.com

 February 22, 2007

 VIA EDGAR AND FACSIMILE

 Jennifer R. Hardy

 Branch Chief

 Division of Corporation Finance

 Securities and Exchange Commission

 100 F Street, N.E.

 Washington, D.C. 20549-0303

Re:
Chicago Mercantile Exchange Holdings Inc.

Registration Statement on Form S-4

Commission File
No. 333-139538

 Dear Ms. Hardy:

 We are writing on behalf of our client, Chicago Mercantile Exchange Holdings Inc. (the
“Company”), in response to the letter of the staff (the “Staff”) of the Division of Corporation Finance of the Securities and Exchange Commission (the “Commission”), dated February 22, 2007 (the “Comment
Letter”), relating to the Company’s Amendment No. 2 to Registration Statement on Form S-4 filed with the Commission on February 20, 2007 (the “Registration Statement”) in connection with the merger of the Company and
CBOT Holdings, Inc. (“CBOT Holdings”).

 Enclosed is a copy of changed pages to the Registration Statement as we propose to file
them in Amendment No. 3 to the Registration Statement, which will also be filed via EDGAR and which have been marked to show changes from Amendment No. 2 to the Registration Statement as previously filed.

 * * * * *

 Securities and Exchange Commission

 February 22, 2007

 Page 2

 After you
have had the opportunity to review the attached, please do not hesitate to contact the undersigned (312-407-0531) or Susan S. Hassan (312-407-0527) with any questions or further comments you may have. Facsimile transmissions may be sent to us at
(312) 407-0411.

 Very truly yours,

 /s/ Rodd M. Schreiber

 Rodd M. Schreiber

 Skadden, Arps, Slate, Meagher & Flom LLP

cc:
Matt Franker (Securities and Exchange Commission)

 Bret
Johnson (Securities and Exchange Commission)

 Jennifer Thompson (Securities and Exchange Commission)

 Kathleen M. Cronin (Chicago Mercantile Exchange Holdings Inc.)

 Susan S. Hassan (Skadden, Arps, Slate, Meagher & Flom LLP)

 Kevin J.P. O’Hara (CBOT Holdings,
Inc.)

 Scott J. Davis (Mayer Brown Rowe and Maw LLP)

 Bruce F. Perce (Mayer Brown Rowe and Maw LLP)

MATERIAL U.S. FEDERAL INCOME TAX CONSEQUENCES OF THE MERGER

 CME Holdings and CBOT Holdings have structured
the merger to qualify as a reorganization within the meaning of Section 368(a) of the Code. As described below under “—Tax Consequences of the Merger Generally,” in connection with the filing of the registration statement of
which this document forms a part, Skadden, Arps has delivered an opinion to CME Holdings, and Mayer Brown has delivered an opinion to CBOT Holdings, to the effect that the merger will be treated as a reorganization within the meaning of
Section 368(a) of the Code.

 The following is a summary of the material U.S. federal income tax consequences of the merger applicable
to a holder of shares of CBOT Holdings Class A common stock that receives CME Holdings Class A common stock or cash in the merger. This discussion is based upon the Code, Treasury regulations, judicial authorities, published positions of
the Internal Revenue Service, or the “IRS,” and other applicable authorities, all as currently in effect and all of which are subject to change or differing interpretations (possibly with retroactive effect). This discussion is limited to
U.S. holders (as defined below) and non-U.S. holders (as defined below) that hold their shares of CBOT Holdings Class A common stock as capital assets for U.S. federal income tax purposes (generally, assets held for investment). This discussion
does not address all of the tax consequences that may be relevant to a particular CBOT Holdings Class A stockholder or to CBOT Holdings Class A stockholders that are subject to special treatment under U.S. federal income tax laws, such as:

•

 financial institutions;

•

 insurance companies;

•

 tax-exempt organizations;

•

 dealers in securities or currencies;

•

 persons whose functional currency is not the U.S. dollar;

•

 traders in securities that elect to use a mark to market method of accounting;

•

 persons that hold CBOT Holdings Class A common stock as part of a straddle, hedge, constructive sale or conversion transaction; and

•

 U.S. holders who acquired their shares of CBOT Holdings Class A common stock through the exercise of an employee stock option or otherwise as compensation.

 If a partnership or other entity taxed as a partnership holds CBOT Holdings Class A common stock, the tax treatment
of a partner in the partnership generally will depend upon the status of the partner and the activities of the partnership. Partnerships and partners in such a partnership should consult their tax advisers about the tax consequences of the merger to
them.

 This discussion does not address the tax consequences of the merger under state, local or foreign tax laws. No assurance can be
given that the IRS would not assert, or that a court would not sustain, a position contrary to any of the tax consequences set forth below.

 Holders of CBOT Holdings Class A common stock should consult with their own tax advisors as to the tax consequences of the merger in their particular circumstances, including the applicability and effect of the alternative minimum
tax and any state, local or foreign and other tax laws and of changes in those laws.

 For purposes of this section, the term “U.S.
holder” means a beneficial owner of CBOT Holdings Class A common stock that for U.S. federal income tax purposes is:

•

 a citizen or resident of the United States;

•

 a corporation or partnership, or other entity treated as a corporation or partnership for federal income tax purposes, created or organized in or under the laws of
the United States or any State or the District of Columbia;

 128

•

 an estate that is subject to U.S. federal income tax on its income regardless of its source; or

•

 a trust, the substantial decisions of which are controlled by one or more U.S. persons and which is subject to the primary supervision of a U.S. court, or a trust
that validly has elected under applicable Treasury regulations to be treated as a U.S. person for U.S. federal income tax purposes.

 For purposes of this section, the term “non-U.S. holder” means a beneficial owner of CBOT Holdings Class A common stock that is not a U.S. holder.

Tax Consequences of the Merger Generally

 CME Holdings and CBOT Holdings have structured the merger to qualify
as a reorganization within the meaning of Section 368(a) of the Code. It is a condition to CME Holdings’ obligation to complete the merger that CME Holdings receive an opinion of its counsel, Skadden, Arps, dated the closing date of the
merger, substantially to the effect that the merger will be treated as a reorganization within the meaning of Section 368(a) of the Code. It is a condition to CBOT Holdings’ obligation to complete the merger that CBOT Holdings receive an
opinion of its counsel, Mayer Brown, dated the closing date of the merger, substantially to the effect that the merger will be treated as a reorganization within the meaning of Section 368(a) of the Code. In connection with the filing of the
registration statement of which this document forms a part, Skadden, Arps has delivered an opinion to CME Holdings, and Mayer Brown has delivered an opinion to CBOT Holdings, to the effect that the merger will be treated as a reorganization within
the meaning of Section 368(a) of the Code. In rendering these opinions, counsel may require and rely upon representations contained in letters and certificates to be received from CME Holdings and CBOT Holdings. In addition, the opinions will
be subject to certain qualifications and limitations as set forth in the opinions. None of the tax opinions given in connection with the merger or the opinions described below will be binding on the IRS. Neither CME Holdings nor CBOT Holdings
intends to request any ruling from the IRS as to the U.S. federal income tax consequences of the merger.

  Consequently, no assurance
can be given that the IRS will not assert, or that a court would not sustain, a position contrary to any of those set forth below. In addition, if any of the representations or assumptions upon which those opinions are based is inconsistent with the
actual facts, the U.S. federal income tax consequences of the merger could be adversely affected.

 The discussion below as to the material
U.S. federal income tax consequences of the merger is the opinion of Skadden Arps and Mayer Brown, subject to the qualifications and limitations referenced and summarized above.

 Tax Consequences of the Merger for CME Holdings, CME Holdings Stockholders and CBOT Holdings

 As a
result of the merger qualifying as a reorganization within the meaning of Section 368(a) of the Code, no gain or loss will be recognized by CME Holdings, CME Holdings stockholders, or CBOT Holdings.

 Tax Consequences of the Merger for CBOT Holdings Stockholders

  Exchange of CBOT Holdings Class A common stock solely for CME Holdings Class A common stock.

•

 For a U.S. holder who exchanges all of its shares of CBOT Holdings Class A common stock solely for shares of CME Holdings Class A common stock in the
merger, no gain or loss will be recognized.

 Exchange of CBOT Holdings Class A common stock solely for cash.

•

 For a U.S. holder who exchanges all of its shares of CBOT Holdings Class A common stock solely for cash in the merger, capital gain or loss equal to the
difference between the amount of cash received and the holder’s tax basis in the CBOT Holdings Class A common stock generally will be recognized.

•

 Any capital gain or loss generally will be long-term capital gain or loss if the U.S. holder held the shares of CBOT Holdings Class A common stock for more
than one year at the time the merger is completed. Long-term capital gain of an individual generally is subject to a maximum U.S. federal income tax rate of 15%. Short-term capital gains of an individual generally are subject to a maximum U.S.
federal income tax rate of 35%. The deductibility of capital losses is subject to limitations.

 129

•

 In some cases, such as if the U.S. holder actually or constructively owns CME Holdings Class A common stock immediately after the merger, such cash received in
the merger could be treated as having the effect of the distribution of a dividend, under the tests set forth in Section 302 of the Code, in which case such cash received would be treated as ordinary dividend income. These rules are complex and
dependent upon the specific factual circumstances particular to each U.S. holder. Consequently, each U.S. holder that may be subject to those rules should consult its tax advisor as to the application of these rules to the particular facts relevant
to such U.S. holder.

 Exchange of CBOT Holdings Class A common stock for combination of CME Holdings Class A
common stock and cash.

•

 For a U.S. holder who exchanges shares of CBOT Holdings Class A common stock for a combination of CME Holdings Class A common stock and cash, gain (but
not loss) will be recognized, and the gain recognized will be equal to the lesser of (i) the excess, if any, of the amount of cash plus the fair market value of any CME Holdings Class A common stock received in the merger, over such U.S.
holder’s tax basis in the shares of CBOT Holdings Class A common stock surrendered by the U.S. holder in the merger, or (ii) the amount of cash received in the merger.

•

 For a U.S. holder who acquired different blocks of CBOT Holdings Class A common stock at different times and at different prices, realized gain or loss
generally must be calculated separately for each identifiable block of shares exchanged in the merger, and a loss realized on the exchange of one block of shares cannot be used to offset a gain realized on the exchange of another block of shares.

•

 If a U.S. holder has differing bases or holding periods in respect of shares of CBOT Holdings Class A common stock, the U.S. holder should consult its tax
advisor prior to the exchange with regard to identifying the bases or holding periods of the particular shares of CME Holdings Class A common stock received in the merger.

•

 Any capital gain generally will be long-term capital gain if the U.S. holder held the shares of CBOT Holdings Class A common stock for more than one year at
the time the merger is completed. Long-term capital gain of an individual generally is subject to a maximum U.S. federal income tax rate of 15%. Capital gains on stock held for one year or less my be taxed at regular rates of up to 35% for
individuals.

•

 In some cases, such as if the U.S. holder actually or constructively owns CME Holdings Class A common stock immediately after the merger, such gain could be
treated as having the effect of the distribution of a dividend, under the tests set forth in Section 302 of the Code, in which case such gain would be treated as ordinary dividend income. These rules are complex and dependent upon the specific
factual circumstances particular to each U.S. holder. Consequently, each U.S. holder that may be subject to those rules should consult its tax advisor as to the application of these rules to the particular facts relevant to such U.S. holder.

 Treatment of non-U.S. holders who exchange CBOT Holdings Class A common stock in the merger.

•

 For a non-U.S. holder who exchanges its shares of CBOT Holdings Class A common stock in the merger, its tax consequences, including the computation of capital
gain or loss, will generally be determined in the same manner as that of a U.S. holder, except as otherwise described below.

•

 A non-U.S. holder generally will not be subject to U.S. federal income tax on any gain recognized with respect to the merger unless (i) such gain is
effectively connected with a trade or business of the non-U.S. holder in the United States (or, if certain income tax treaties apply, is attributable to a permanent establishment), (ii) CBOT Holdings is a U.S. real property holding corporation
(as defined below) at any time within the shorter of the five-year period ending on the date on which the proposed transaction is consummated or such non-U.S. holder’s holding period or (iii) the non-U.S. holder is an individual who is
present in the United States for a period or periods aggregating 183 or more days in the taxable year of the exchange and certain other conditions are met, (iv) or cash paid to a non-U.S. holder in the merger for some or all of such non-U.S.
holder’s CBOT Holdings Class A common stock

 130

has the effect of a distribution of a dividend for U.S. federal income tax purposes. In the case of (i)-(iii), a non-U.S. holder will be subject to U.S.
federal income tax on such gain in the same manner as a U.S. holder. In addition, a non-U.S. holder that is a corporation may be subject to a branch profits tax equal to 30% (or lesser rate under an applicable income tax treaty) on such effectively
connected income.

•

 Generally, a corporation is a “U.S. real property holding corporation” if the fair market value of its U.S. real property interests, as defined in the
Code and applicable regulations, equals or exceeds 50% of the aggregate fair market value of its worldwide real property interests and its other assets used or held for use in a trade or business. CBOT Holdings does not believe that it is or has
been a U.S. real property holding corporation within the last five years and does not expect to become a U.S. real property holding corporation prior to the date of closing of the merger.

•

 If a non-U.S. holder in the merger receives a cash payment in exchange for all or some of its CBOT Holdings Class A common stock that has the effect of a
distribution of a dividend for U.S. federal income tax purposes, then such cash payment m

CORRESP
1
filename1.htm

Acceleration Request Letter

 CHICAGO MERCANTILE EXCHANGE HOLDINGS INC.

 20 South Wacker Drive

 Chicago, Illinois 60606

 (312) 930-1000

 February 22, 2007

VIA EDGAR AND FACSIMILE

 Jennifer R. Hardy

 Branch Chief

 Division of Corporation Finance

 Securities and Exchange Commission

 100 F. Street, N.E.

 Washington, D.C. 20549-0303

RE:

Chicago Mercantile Exchange Holdings Inc.

Registration Statement on Form S-4 (File No. 333-139538)

 Dear Ms. Hardy:

 Pursuant to Rule 461 of the Securities Act of 1933, as amended, Chicago Mercantile Exchange Holdings Inc. (the “Registrant”), respectfully requests that the effective date of the Registration Statement on
Form S-4 (File No. 333-139538) filed by the Registrant on December 21, 2006, be accelerated by the Securities and Exchange Commission (the “Commission”) to February 26, 2007 at 3:00 p.m., Eastern Time, or as soon as
practicable thereafter.

 The Registrant hereby acknowledges that:

•

 should the Commission or the staff, acting pursuant to delegated authority, declare the filing effective, it does not foreclose the Commission from taking any
action with respect to the filing;

•

 the action of the Commission or the staff, acting pursuant to delegated authority, in declaring the filing effective, does not relieve the Registrant from its full
responsibility for the adequacy and accuracy of the disclosure in the filing; and

•

 the Registrant may not assert staff comments and the declaration of effectiveness as a defense in any proceeding initiated by the Commission or any person under the
federal securities laws of the United States.

 The Registrant respectfully requests that it be notified of such
effectiveness by a telephone call to Michael P. McGrane of Skadden, Arps, Slate, Meagher & Flom LLP at (312) 407-0808 and that such effectiveness also be confirmed in writing.

 Very truly yours,

 CHICAGO MERCANTILE EXCHANGE HOLDINGS INC.

 By:

 /s/ Kathleen M. Cronin

 Name:

Kathleen M. Cronin

 Title:

Managing Director, General Counsel and Corporate Secretary

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549-7010
         DIVISION OF
CORPORATION FINANCE

February 22, 2007

Mail Stop 7010

By U.S. Mail and facsimile to (312) 407-8522

Kathleen M. Cronin
Managing Director, General Couns el and Corporate Secretary
Chicago Mercantile Exchange Holdings Inc.
20 South Wacker Drive
Chicago, Illinois 60606

Re:  Chicago Mercantile Exchange Holdings Inc.
 Amendment No. 2 to Registrati on Statement on Form S-4
Filed February 20, 2007
 File No. 333-139538

Dear Ms. Cronin:

We have reviewed your filings and have the following comments.  We welcome
any questions you may have about our comments or any other aspect of  our review.  Feel
free to call us at the telephone numbers  listed at the end of this letter.

Exhibits

1. We note your response to comment 12 of our letter dated February 15, 2007.
Please note that counsel mu st opine on the tax conseque nces of the transaction,
not the manner in which they are described in the prospectus. In this respect, we
note the language on page 129 that it is a condition that you receive an opinion of
counsel . . . substantially to  the effect that the merger will be treated as a
reorganization and that Skadden Arps has delivered an opinion to CME Holdings,
and Mayer Brown has delivered an opinion to  CBOT Holdings, to the effect that
the merger will be treated as a reorga nization.  Please revi se the prospectus
disclosure U.S. Federal Income Tax Conse quences of the Merger to delete this
language and to state clearly what counsels’ opinions are,  i.e. that the transaction
will be treated as a reorganization, or alternatively submit revised tax opinions
directly opining on each material consequence of the merger to the parties and their shareholders.

Kathleen M. Cronin
Chicago Mercantile Exch ange Holdings Inc.
February 22, 2007 Page 2
You may contact Bret Johns on, Staff Accountant, at (202) 551-3753 or Jennifer
Thompson, Senior Staff Accountant, at (202)  551-3737 if you have questions regarding
comments on the financial statements and related matters.  Please contact Matt Franker, Staff Attorney, at (202) 551-3749 or me, at  (202) 551-3767 with any other questions.

Sincerely,

Jennifer R. Hardy
Branch Chief

cc: Rodd M. Schreiber
Susan S. Hassan
Skadden, Arps, Slate, Meagher & Flom LLP
333 West Wacker Drive
Chicago, Illinois 60606

CORRESP
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filename1.htm

Response Letter and Comments

 Skadden, Arps, Slate, Meagher & Flom LLP

 333 West Wacker Drive

 Chicago, Illinois 60606

 Tel: (312) 407-0700

 Fax: (312) 407-0411

 http://www.skadden.com

 February 20, 2007

 VIA
EDGAR AND FACSIMILE

 Jennifer R. Hardy

 Branch Chief

 Division of Corporation Finance

 Securities and Exchange Commission

 100 F Street, N.E.

 Washington, D.C. 20549-0303

Re:

Chicago Mercantile Exchange Holdings Inc.

Amendment No. 1 to Registration Statement on Form S-4

Filed January 30, 2007

Commission File No. 333-139538

 Dear Ms. Hardy:

 We are writing on behalf of our client, Chicago Mercantile Exchange Holdings Inc. (the “Company”), in response to the letter of the staff (the
“Staff”) of the Division of Corporation Finance of the Securities and Exchange Commission (the “Commission”), dated February 15, 2007 (the “Comment Letter”), relating to the Company’s Amendment No. 1 to
Registration Statement on Form S-4 filed with the Commission on January 30, 2007 in connection with the merger of the Company and CBOT Holdings, Inc. (“CBOT Holdings”).

 For the convenience of the Staff, the responses are set forth below following the text of the paragraph of the Comment
Letter to which each response relates. Enclosed is a copy of Amendment No. 2 to the Registration Statement (“Amendment No. 2”), which is being filed via EDGAR concurrently herewith and which has been marked to show changes from
Amendment No. 1 to the Registration Statement as previously filed. The page references in the responses to the Staff’s comments refer to Amendment No. 2.

 General

1.

We note the recommendation of CBOT’s board of directors with respect to the proposal to vote upon an adjournment or postponement to solicit additional proxies. Please
confirm that neither the board of directors of CME nor CBOT Holdings has issued a recommendation with respect to the proposals to vote upon an adjournment or postponement of the meetings of the CME stockholders or CBOT Holdings Class A
Stockholders or, otherwise, revise the letters to the companies’ respective stockholders to disclose the respective recommendations.

 Response: Neither the board of directors of the Company nor CBOT Holdings has issued a recommendation with respect to the proposal to vote on an adjournment or
postponement. CBOT’s letter to members in the Registration Statement has been revised in response to this comment.

 Kathleen M. Cronin

 Chicago
Mercantile Exchange Holdings Inc.

 February 20, 2007

  Page
 2

 Summary, page 1

 Questions and Answers About the Merger, page 1

 What will CBOT Holdings Class A stockholders receive in the merger?, page 1

2.

We note your responses to comments 5 and 6 of our letter dated January 23, 2007, as well as the calculation of the total preliminary purchase price on page 140. To provide
investors with a more thorough understanding of the value of the merger consideration, please revise your disclosure here and on page 140 to disclose such consideration as of the most recent practicable date since there have been significant
fluctuations in CME’s stock price.

 Response: The
Registration Statement has been revised on page 2 and in the pro forma financial information section in response to this comment.

 Other Information Regarding the Merger, page 9

 CBOT Holdings
Financial Advisor…, page 10

3.

We note your response to comment 8 of our letter dated January 23, 2007. Please revise to disclose the percentage of the total consideration that will be paid by CBOT
Holdings to JPMorgan if the merger is consummated.

 Response: The Registration Statement has been revised on page 11 in response to this comment to disclose the percentage of the total consideration that will be paid by CBOT Holdings to JPMorgan if the merger is consummated.

 Opinion of Lehman Brothers, Financial Advisor to CME Holdings, page 69

 Comparable Company Analysis, page 71

4.

We note your response to comment 19 of our letter dated January 23, 2007. It is unclear to us whether the qualitative judgments made by Lehman Brothers were to disregard the
quantitative results for the companies listed on page 71, other than those identified as most closely matching the financial and operating characteristics of CBOT Holdings or, alternatively, whether such judgments resulted in adjustments to a larger
quantitative analysis. If the reference range for the implied share price of CBOT Holdings was calculated solely by reference to the three companies identified in your response, so state.

 Response: The Registration Statement has been revised on page 73 in response to this
comment.

 CBOT Discounted Cash Flow Analysis, page 73

5.

We note your response to comment 20 of our letter dated January 23, 2007. Please expand your discussion to disclose the companies selected by Lehman Brothers for its
determination of the future market volatility component of its weighted average cost of capital calculation. In addition, please revise the statement that “discount rates utilized in this analysis were chosen by Lehman Brothers based on its
expertise and experience … and also on an analysis of the weighted average cost of capital of CBOT Holdings” to clarify whether the Lehman Brothers utilized its “expertise and experience” in calculating the weighted average cost
of capital, which was used as the discount rate, or whether such “expertise and experience” was used in adjusting the calculation of the weighted average cost of capital to reach the range of discount rates used in the analysis.

 Response: The Registration Statement has been revised
on pages 74 and 75 in response to this comment.

 Kathleen M. Cronin

 Chicago
Mercantile Exchange Holdings Inc.

 February 20, 2007

  Page
 3

 Opinion of JP Morgan,
Financial Advisor to CBOT Holdings, page 83

6.

We note your response to comment 23 of our January 23 letter. Please revise to make the disclosures requested in that comment in your discussion of the opinions of JPMorgan
and Lazard.

 Response: The Registration Statement has
been revised on pages 85 and 91 in response to this comment.

 Publicly
Traded Comparable Company Analysis, page 86

7.

We note your revision on page 86 in response to comment 18 of our January 23 letter. Please revise to disclose the criteria that JPMorgan used in determining which companies
were “relevant.”

 Response: The Registration
Statement has been revised on page 87 in response to this comment.

 Discounted Cash Flow Analysis, page 87

8.

We note your revised disclosure regarding the range of discount rates selected. Please expand your disclosure to discuss the analyses of selected publicly traded companies
engaged in relevant businesses that were performed, as well as the companies deemed relevant, in calculating the applicable discount rate.

 Response: The Registration Statement has been revised on page 88 in response to this comment.

 The Merger Agreement, page 109

 Representations and Warranties, page 117

9.

We note your response to comment 28 of our letter dated January 23, 2007. Please provide us with a list briefly identifying the contents of all omitted schedules.

 Response: The Company is providing, supplementally
under separate cover, a list briefly identifying the contents of the parties’ confidential disclosure schedules.

 Conditions to Complete the Merger, page 120

10.

We note your response to comment 29 of our January 23 letter. Please revise your discussion to briefly describe the facts under which the parties may waive an existing
condition to the merger.

 Response: The Registration
Statement has been revised on page 122 in response to this comment.

 Exhibits

 Exhibit 5.1, Form of Opinion of Kathleen M. Cronin… regarding legality of the securities being issued

11.

Please confirm that the reference in the fifth paragraph of the opinion to the corporate laws of the State of Delaware includes all statutes, including the rules and regulations
underlying those provisions, applicable judicial and regulatory determinations, and applicable provisions of the Delaware Constitution.

 Response: The Company confirms that the reference in the fifth paragraph of the opinion to the corporate laws of the State of Delaware includes all statutes,
including the rules and regulations underlying those provisions, applicable judicial and regulatory determinations, and applicable provisions of the Delaware Constitution.

 Kathleen M. Cronin

 Chicago
Mercantile Exchange Holdings Inc.

 February 20, 2007

  Page
 4

 Exhibit 8.1, Form of Opinion
of Skadden Arps… relating to tax matters

12.

We note the opinion is that the merger will qualify as a reorganization within the meaning of Section 368(a) of the Internal Revenue Code. Please submit a revised opinion
clarifying that the consequence of such a qualification is that the merger is tax free. Submit a similarly revised opinion with respect to the tax consequences of the merger to CBOT Holdings, Inc.

 Response: The opinions of Skadden, Arps and Mayer Brown have been revised in response
to this comment.

13.

The assumptions that the merger will qualify as a statutory merger under Delaware law and that the merger agreement will be enforceable should be deleted, as the tax opinion
cannot assume any legal conclusion underlying the opinion.

 Response: The opinion of Skadden, Arps has been revised in response to this comment.

14.

The statement of reliance upon the statements and representations of the officers and other representatives of the parties should be revised to indicate that such reliance is
limited to factual matters or, alternatively, the statement should be deleted.

 Response: The opinion of Skadden, Arps has been revised in response to this comment.

15.

The revised tax opinion should delete the statement that the opinion “is expressed as of the date hereof,” as such opinion must speak as of the date of effectiveness of
the registration statement.

 Response: The opinion of
Skadden, Arps has been revised in response to this comment.

16.

We note the statement in the second to last paragraph that the “letter has been prepared for you solely in connection with the Merger.” It is unclear to us whom counsel
is referring to in its use of “you.” Note that use of the tax opinion may not be limited to the board of directors or to the registrant.

 Response: The opinion of Skadden, Arps has been revised in response to this comment.

 17. Please also include the signature of counsel in your revised tax opinion.

 Response: An executed copy of all three legal opinions will be
filed with the final amendment to the Registration Statement.

 Exhibit 8.2,
Form of Opinion of Mayer, Brown, Rowe & Maw LIT relating to tax matters

18.

Please submit a revised opinion of counsel that does not contain an assumption regarding the enforceability of the merger agreement.

 Response: The opinion of Mayer Brown has been revised in response to this comment.

 Kathleen M. Cronin

 Chicago
Mercantile Exchange Holdings Inc.

 February 20, 2007

  Page
 5

 Closing Comment

19.

Please also review the representations requested on page 7 of our letter dated January 23, 2007, and provide these representations in the form requested.

 Response: The Company confirms to the Staff that its
request for acceleration will include the representations requested on page 7 of the Staff’s letter dated January 23, 2007.

 * * * * *

 After you have had the opportunity to review the attached, please do not hesitate to contact the undersigned (312-407-0531) or Susan S. Hassan
(312-407-0527) with any questions or further comments you may have. Facsimile transmissions may be sent to us at (312) 407-0411.

 Very truly yours,

 /s/ Rodd M. Schreiber

 Rodd M. Schreiber

 Skadden, Arps, Slate, Meagher & Flom LLP

cc:

Matt Franker (Securities and Exchange Commission) Bret Johnson (Securities and Exchange Commission) Jennifer Thompson (Securities and Exchange Commission) Kathleen M. Cronin
(Chicago Mercantile Exchange Holdings Inc.) Susan S. Hassan (Skadden, Arps, Slate, Meagher & Flom LLP) Kevin J.P. O’Hara (CBOT Holdings, Inc.) Scott J. Davis (Mayer Brown Rowe and Maw LLP) Bruce F. Perce (Mayer Brown Rowe and Maw LLP)

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549-7010
         DIVISION OF
CORPORATION FINANCE

February 15, 2007

Mail Stop 7010

By U.S. Mail and facsimile to (312) 407-8522

Kathleen M. Cronin
Managing Director, General Couns el and Corporate Secretary
Chicago Mercantile Exchange Holdings Inc.
20 South Wacker Drive
Chicago, Illinois 60606

Re:  Chicago Mercantile Exchange Holdings Inc.
 Amendment No. 1 to Registrati on Statement on Form S-4
Filed January 30, 2007
 File No. 333-139538

Dear Ms. Cronin:

We have reviewed your filings and have the following comments.  We welcome
any questions you may have about our comments or any other aspect of  our review.  Feel
free to call us at the telephone numbers  listed at the end of this letter.

General

1. We note the recommendation of CBOT’s board  of directors with respect to the
proposal to vote upon an adjournment or  postponement to solicit additional
proxies.  Please confirm that neither the board of directors of CME nor CBOT
Holdings has issued a recommendation with  respect to the proposals to vote upon
an adjournment or postponement of the meetings of the CME stockholders or CBOT Holdings Class A Stockholders or, ot herwise, revise the letters to the
companies’ respective stockholders to di sclose the respective recommendations.

Summary, page 1
Questions and Answers About the Merger, page 1
What will CBOT Holdings Class A stockholde rs receive in the merger?, page 1

2. We note your responses to comments 5 a nd 6 of our letter dated January 23, 2007,
as well as the calculation of  the total preliminary purch ase price on page 140.  To
provide investors with a mo re thorough understanding of the value of the merger

Kathleen M. Cronin
Chicago Mercantile Exch ange Holdings Inc.
February 15, 2007 Page 2
consideration, please revise your disclosure here and on page 140 to disclose such consideration as of the most recent pr acticable date since there have been
significant fluctuations in CME’s stock price.

Other Information Regarding the Merger, page 9
CBOT Holdings Financial Advisor . . ., page 10

3. We note your response to comment 8 of our letter dated January 23, 2007.  Please
revise to disclose the percentage of th e total consideration that will be paid by
CBOT Holdings to JPMorgan if the merger is consummated.

Opinion of Lehman Brothers, Financia l Advisor to CME Holdings, page 69
Comparable Company Analysis, page 71

4. We note your response to comment 19 of our  letter dated January 23, 2007.  It is
unclear to us whether the qualitative j udgments made by Lehm an Brothers were
to disregard the quantitati ve results for the compan ies listed on page 71, other
than those identified as most closel y matching the financ ial and operating
characteristics of CBOT Holdings or, alternatively, whether such judgments resulted in adjustments to a larger quantita tive analysis.  If th e reference range for
the implied share price of CBOT Holdings  was calculated solely by reference to
the three companies identified in  your response, so state.

CBOT Discounted Cash Flow Analysis, page 73

5. We note your response to comment 20 of our letter dated January 23, 2007.  Please expand your discussion to disclose  the companies selected by Lehman
Brothers for its determination of the fu ture market volatility component of its
weighted average cost of capital calcul ation.  In addition, please revise the
statement that “discount rates utilized in  this analysis were chosen by Lehman
Brothers based on its expertise and experien ce . . . and also on an analysis of the
weighted average cost of capital of CBOT Holdings” to clarify whether the
Lehman Brothers utilized its “expertis e and experience” in calculating the
weighted average cost of capital, which was used as the discount rate, or whether such “expertise and experience” was used  in adjusting the calculation of the
weighted average cost of cap ital to reach the range of discount rates used in the
analysis.

Opinion of JP Morgan, Financial Advisor to CBOT Holdings, page 83

6. We note your response to comment 23 of our  January 23 letter.  Please revise to
make the disclosures requested in that comment in your discussion of the opinions of JPMorgan and Lazard.

Kathleen M. Cronin
Chicago Mercantile Exch ange Holdings Inc.
February 15, 2007 Page 3
Publicly Traded Comparable Company Analysis, page 86

7. We note your revision on page 86 in re sponse to comment 18 of our January 23
letter.  Please revise to disclose the crit eria that JPMorgan used in determining
which companies were “relevant.”

Discounted Cash Flow Analysis, page 87

8. We note your revised disclosure regarding the range of discount  rates selected.
Please expand your disclosure to discuss th e analyses of selected publicly traded
companies engaged in relevant businesse s that were performed, as well as the
companies deemed relevant, in calcul ating the applicab le discount rate.

The Merger Agreement, page 109
Representations and Warranties, page 117

9. We note your response to comment 28 of our letter dated January 23, 2007.  Please provide us with a list briefly identifying the contents of all omitted schedules.

Conditions to Complete the Merger, page 120

10. We note your response to comment 29 of our January 23 letter.  Please revise
your discussion to briefly describe the facts under which the parties may waive an existing condition to the merger.

Exhibits
Exhibit 5.1, Form of Opinion of Kathleen M.  Cronin . . . regarding legality of the
securities being issued

11. Please confirm that the reference in th e fifth paragraph of the opinion to the
corporate laws of the State of Delaware  includes all statutes , including the rules
and regulations underlying those provisions , applicable judicial and regulatory
determinations, and applicable provisions of the Delaware Constitution.

Exhibit 8.1, Form of Opinion of Skadde n Arps . . . relating to tax matters

12. We note the opinion is that the merger will qualify as a reorganization within the meaning of Section 368(a) of  the Internal Revenue Code.  Please submit a revised
opinion clarifying that the consequence of such a qualification is that the merger
is tax free.  Submit a similarly revi sed opinion with respect to the tax
consequences of the merger to CBOT Holdings, Inc.

Kathleen M. Cronin
Chicago Mercantile Exch ange Holdings Inc.
February 15, 2007 Page 4

13. The assumptions that the merger wi ll qualify as a statutory merger under
Delaware law and that the merger agreement will be enforceable should be deleted, as the tax opinion cannot assume any legal conclusion underlying the opinion.

14. The statement of reliance upon the statemen ts and representations of the officers
and other representatives of the parties should be revised to indicate that such
reliance is limited to factual matters or , alternatively, the statement should be
deleted.

15. The revised tax opinion should delete the statement that the opinion “is expressed
as of the date hereof,” as such opinion mu st speak as of the date of effectiveness
of the registration statement.

16. We note the statement in the second to la st paragraph that the “letter has been
prepared for you solely in connection with th e Merger.”  It is unclear to us whom
counsel is referring to in its  use of “you.”  Note that use of the tax opinion may
not be limited to the board of directors or to the registrant.

17. Please also include the signature of counsel in your revised tax opinion.

Exhibit 8.2, Form of Opinion of Mayer, Brown, Rowe & Maw LLP relating to tax
matters

18. Please submit a revised opinion of counsel that does not contain an assumption
regarding the enforceability of the merger agreement.

Closing Comment

19. Please also review the representations requested on page 7 of our letter dated
January 23, 2007, and provide these repres entations in the form requested.

Kathleen M. Cronin
Chicago Mercantile Exch ange Holdings Inc.
February 15, 2007 Page 5
You may contact Bret Johns on, Staff Accountant, at (202) 551-3753 or Jennifer
Thompson, Senior Staff Accountant, at (202)  551-3737 if you have questions regarding
comments on the financial statements and related matters.  Please contact Matt Franker, Staff Attorney, at (202) 551-3749 or me, at  (202) 551-3767 with any other questions.

Sincerely,

Jennifer R. Hardy
Branch Chief

cc: Rodd M. Schreiber
Susan S. Hassan
Skadden, Arps, Slate, Meagher & Flom LLP
333 West Wacker Drive
Chicago, Illinois 60606

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549-7010
         DIVISION OF
CORPORATION FINANCE

January 23, 2007

Mail Stop 7010

By U.S. Mail and facsimile to (312) 407-8522

Kathleen M. Cronin
Managing Director, General Couns el and Corporate Secretary
Chicago Mercantile Exchange Holdings Inc.
20 South Wacker Drive
Chicago, Illinois 60606

Re:  Chicago Mercantile Exchange Holdings Inc.
 Registration Statement on Form S-4
Filed December 21, 2006
 File No. 333-139538

Dear Ms. Cronin:

We have reviewed your filings and have the following comments.  Where
indicated, we think you should re vise your documents in response to these comments.  If
you disagree, we will consider your explanation as to why our comment is inapplicable or
a revision is unnecessary.  Please be as deta iled as necessary in your explanation.  In
some of our comments, we may ask you to provide us with supplemental information so
we may better understand your disclosure.  After reviewing this information, we may
raise additional comments.

Please understand that the purpose of our re view process is to assist you in your
compliance with the applicable disclosure  requirements and to  enhance the overall
disclosure in your filing.  We look forward to  working with you in these respects.  We
welcome any questions you may have about our comments or any other aspect of our review.  Feel free to call us at the telephone numbers listed at the end of this letter.

General

1. Please provide for staff review all materials prepared by the parties’ financial advisors and provided to their respective boa rds, or their representatives.  Provide
the board books and all transcripts, summar ies, and video presentation materials.
We may have further comment based on our review of these materials.

Kathleen M. Cronin
Chicago Mercantile Exch ange Holdings Inc.
January 23, 2007 Page 2
2. We note that each solicitation will seek discretion to vote on other business that
may come before the meeting or any ad journment, including an adjournment for
the purpose of soliciting additional proxies.  If you contemplate adjourning the
meeting to solicit additional proxies, this action must appear as  a separate item for
shareholder approval, as it is not an incidental matter as contemplated by
Exchange Act Rule 14a-4(c)(7).  Refer also to Rule 14a-4(a)(3).

3. In addition, please revise your discussion of each matter to be voted upon in the
respective special meetings to number each proposal for which proxies will be
solicited.

4. We note disclosure on page 28 regardi ng indebtedness that CME may incur to
finance the cash portion of the merger  consideration.  Please revise the
registration statement to disclose whet her you have obtained commitments for the
cash portion of the merger considerati on.  If you have obtained commitments,
please describe terms of  such agreement(s).

Summary, page 1
Questions and Answers About the Merger, page 1
What will CBOT Holdings Class A stockholde rs receive in the merger?, page 1

5. Please disclose the aggregate market value of the consideration to be received in the merger on the last trading day prior to the pub lic announcement.

6. Please clarify in the last full sentence on page 1 that the value of the cash merger
consideration will fluctuate

What vote is required to a pprove the merger?, page 5

7. Please disclose what percentage of un affiliated stockholders of each company
needs to vote for the merger in orde r to approve the transaction.  Where
appropriate, please provide this in formation elsewhere in the filing.

Other Information Regarding the Merger, page 9
CME Holdings Financial Advisors . . ., page 9

8. Please revise your disclosure in this s ection to specify the fee paid to each
financial advisor, as well as the financial advisor to the CBOT Special
Transaction Committee.  Include disclosure  regarding the fee that is contingent
upon completion of the merger.

Kathleen M. Cronin
Chicago Mercantile Exch ange Holdings Inc.
January 23, 2007 Page 3
Role and Recommendations of the CBT Holdings’ Special Transaction Committee and
Non-ER Members Committee, page 11

9. Briefly describe the exercise right.

The Merger Generally Will Be Tax-Free…, page 17

10. Please revise to state counsel’s opini on here and on page 125 and to identify
counsel here.

Summary Unaudited Pro Forma Condensed Consolidated Financial Data, page 21

11. Please tell us what consideration you ga ve to disclosing tota l assets and cash
dividends per share.  Refer to Item 3(e)  of Form S-4 and Item 301 of Regulation
S-K.

Comparative Per Share Data, page 21

12. Please tell us what consideration you gave to disclosing basic earnings per share.

13. Please tell us what consideration you gave to disclosing cash dividends per share
for the interim period.  Refer to Item 3(f)(2) of Form S-4 and the related
instructions.

Risk Factors, page 23

14. Please revise to discuss the dilution to CME shareholders.

The Special Meeting of CME Ho ldings Stockholders, page 34
Vote Required, page 34

15. Please revise your discussion of any propos al to adjourn or postpone the meeting
to clarify whether the vote required to approve such ac tion is a majority of the
shares outstanding, present, or voting on the matter.

The Merger, page 46
Background of the Merger, page 46

16. We note your statement appearing on page  47 that the parties’ March 7, 2006,
confidentiality agreement addressed disclosure of “confidential information relating to the clearing li nk, as well as other poten tial business arrangements
between the parties.”  Please revise the di sclosure to specify the “other potential
business arrangements” that were included in the agreement.

Kathleen M. Cronin
Chicago Mercantile Exch ange Holdings Inc.
January 23, 2007 Page 4
Certain Projections, page 66

17. Please confirm that the financial projections  appearing in this section include all
material financial projections that were exchanged by the parties or, alternatively,
provide us supplementally with complete c opies of these projections.  In addition,
please provide us supplementally with the financial information that the parties
prepared for their respectiv e financial advisors.  We may have further comment
upon review of your response.

Opinion of Lehman Brothers Financia l Advisor to CME Holdings, page 68

18. For each analysis performed that include s information about other companies or
transactions, please disclose if companie s or transactions meeting the criteria
established by Lehman Brothers were excl uded from the analysis and, if so, the
reason(s) for exclusion.  Pleas e similarly revise the discussions of similar analyses
performed by William Blair, JPMorgan, and Lazard.

Comparable Company Analysis, page 70

19. We note your statement regarding the “inherent differences” between CBOT
Holdings and the companies used in this analysis.  To provide your shareholders
with a better understanding of these inherent differences, as well as the extent to
which Lehman Brothers made qualitative ad justments to provide context to the
quantitative adjustments, please revise the discussion of this analysis to quantify
the size of the qualitative adjustment or  indicate the modified ratios used in
calculating the implied share price of CBOT Holdings.

CBOT Discounted Cash Flow Analysis, page 72

20. Please revise your disclosure to discuss the basis for the perpetual growth rate
used in this analysis, as well as the method by which Lehman Brothers selected
public companies to calculate the applicable discount rate.  Please also discuss the
extent to which Lehman utilized CBOT Holdings’ weighted average cost of
capital and comparable company informati on in calculating the range of discount
rates used in this analysis, as well as the advantages and disadvantages of each method.

Opinion of William Blair, Financial Advisor to CME Holdings, page 75

21. In the last bullet of items that William Blair examined on page 76, please either
describe the other publicly available informa tion or delete the reference.  Also, in
the next paragraph, please describe the other matters that William Blair
considered.  Please also comply in the la st bullet on pages 83 with respect to the
JPMorgan opinion and 89 with respect to the Lazard opinion.

Kathleen M. Cronin
Chicago Mercantile Exch ange Holdings Inc.
January 23, 2007 Page 5
Discounted Cash Flow Analysis, page 78

22. Please revise to briefly discuss the basis for the perpetual growth rate used beyond
2016.

Opinion of JPMorgan, Financial Advisor to CBOT Holdings, page 82

23. Please disclose the basis for JPMorgan’s assumption that the financial projections
provided by the parties were reasonably pr epared.  Also, in an appropriate place
in this disclosure, please indicate wh ether the respective boards reviewed, for
accuracy and completeness, this financia l information and whether the boards
found JPMorgan’s reliance upon those material s to be reasonable.  Make similar
revisions to the discussion of the opinion rendered by Lazard, financial advisor to
the CBOT Holdings Special Transaction Committee on page 89.

Discounted Cash Flow Analysis, page 86

24. Please revise to briefly discuss the basis for the perpetual growth rate used beyond
2015, as well as the basis utilized in determining the discount rate.

Representations and Warranties, page 114

25. Please revise the disclosure under this  heading to summarize the material
representations and warranties of the part ies, rather than addressing the general
subject matter of such repr esentations and warranties.

26. We note your disclosure that the repres entations and warranties were made only
as of the date of the merger agreement.   Please be advised that, notwithstanding
the inclusion of this disclaimer, you are responsible for considering whether additional specific disclosures of mate rial information regarding material
contractual provisions are re quired to make the statem ents in the proxy statement
not misleading.  Please confirm your understa nding.  In addition, please revise to
include disclosure acknowledging that if specific material facts exist that contradict the representati ons or warranties in the me rger agreement, you have
provided corrective disclosure.

27. We note the statement that the represen tations and warranties in the merger
agreement are made solely for the benefit of the parties and should not be relied
upon by any other person.  Please revise  to more clearly state that the
representations and warranties should be read with consideration given to the entirety of public disclosure regarding the parties as set forth in their respective reports with the SEC.  As currently drafted, the disclosure may still imply that the representations and warranties do not const itute public disclosure for purposes of
the federal securities laws.

Kathleen M. Cronin
Chicago Mercantile Exch ange Holdings Inc.
January 23, 2007 Page 6

28. Please provide us with a list that briefl y identifies the contents of all omitted
schedules or any supplements to the merger agreement.

Conditions to Complete Merger, page 119

29. Briefly describe the facts under whic h you may waive the conditions to the
merger, and any circumstances under wh ich you would re-solicit shareholders’
votes.

Regulatory Approvals, page 123

30. Please update information relating to regulatory approvals as applicable.

Unaudited Pro Forma Condensed Combin ed Financial Information, page 133

31. Your pro forma footnotes refer to various  nonrecurring charges th at are related to
the merger.  Please tell us what consid eration you gave to revising the line item
labeled “net income” on your pro forma inco me statements to read “net income
before nonrecurring charges directly attri butable to the transaction.”  Refer to
Article 11-02(b)(5) of Regulation S-X.  Also confirm to us that all nonrecurring
charges that are directly related to the merger have been accrued for in the pro
forma balance sheet.  Refer to Article 11-02(b)(6) of Regulation S-X.

32. We note your discussion of merger-related transaction costs in footnote 2(iii).
Please tell us whether these costs include  the fees that CME Holdings and CBOT
Holdings will pay for fairness opinions.  If not, please tell us what consideration
you gave to quantifying thes e fees in your pro forma footnotes and accruing for
these fees in your pro forma balance sheet.

33. We note your purchase price allocation in f ootnote 2(iii).  We also note from the
merger agreement that you are assuming the pension and other employee benefit plans of CBOT Holdings.  Please tell us what consideration you gave to recording
a purchase accounting adjustment to record these assumed liabilities at fair value.

34. We note on page 100 the discussion of Bernard Dan’s severance payment,
retention bonus, and fee to be a special a dvisor to CME Holdings, all of which are
directly related to the merger.  There a ppear to be retention bonuses payable to
other executives of CBOT Holdings as well.   Please tell us what consideration
you gave to quantifying these payments in  your pro forma footnotes and accruing
for these payments in your  pro forma balance sheet.

35. It appears from footnote 3(D) that you have  assigned $1 billion to the identifiable
intangible asset “Clearing firm relationships.”  Please he lp us to understand if or

Kathleen M. Cronin
Chicago Mercantile Exch ange Holdings Inc.
January 23, 2007 Page 7
how this differs from the clearing servi ces that CME Holdings currently provides
to CBOT Holdings, as discussed on page 107.

Comparative Rights of Stoc kholders . . ., page 145

36. Please delete the statement that the disc losure appearing unde r this heading is
“qualified in its entirety by reference to the Delaware General Corporation Law . . . .”  Information contained in the prosp ectus may not be qualified to information
not included in the re gistration statement.

As appropriate, please amend your registration statement in response to these
comments.  You may wish to provide us with marked copies of the amendment to expedite
our review.  Please furnish a cover letter with your amendment that keys your responses to
our comments and provides any requested information.  Detailed cover letters greatly facilitate our review.  Please understand th at we may ha ve additional comments after
reviewing your amendment and responses to our comments.

We urge all persons who are responsible for the accuracy and adequacy of the
disclosure in the filing to be  certain that the filing includes all information required under
the Securities Act of 1933 and that they have provided all informatio n investors require for
an informed investment deci sion.  Since the company and its  management are in possession
of all facts relating to a company’s disclosure , they are responsible for the accuracy and
adequacy of the disclosures they have made.

Notwithstanding our comments, in the even t the company requests acceleration of
the effective date of the pending registration st atement, it should furnish a letter, at the time
of such request, acknowledging that:

• should the Commission or the staff, acting pursuant to delegated authority, declare
the filing effective, it does not  foreclose the Commission from taking any action with
respect to the filing;

• the action of the Commission or  the staff, acting pursuant to delegated authority, in
declaring the filing effective, does not re lieve the company from its full responsibility
for the adequacy and accuracy of the disclosure in  the filing; and

• the company may not assert staff comments and the declara tion of effectiveness as a
defense in any proceeding initiated by the Commission or any person under the
federal securities laws of the United States.

In addition, please be advise d that the Divisi on of Enforcement has access to all
information you provide to the staff of the Division of Corporation Finance i

CORRESP
1
filename1.htm

Correspondence Letter

 October 19, 2006

 VIA EDGAR TRANSMISSION AND FACSIMILE

 Securities and Exchange Commission

 Division of Corporate Finance

 450 Fifth Street, N.W.

 Washington, D.C. 20549

 Mail Stop 4561

Attention:

Don Walker, Senior Assistant Chief Accountant

John Spitz, Staff Accountant

RE:
Chicago Mercantile Exchange Holdings Inc.

 Form 10-K for the year ended December 31, 2005

 Filed March 6, 2006

 File No. 000-33379

 Ladies and Gentlemen:

 Chicago Mercantile Exchange Holdings Inc. (the “Company”) has received and reviewed the comments
from the staff of the Division of Corporate Finance (the “Staff”) of the Securities and Exchange Commission (the “Commission”) contained in a letter from Don Walker, Senior Assistant Chief Accountant, dated October 3, 2006,
regarding the Commission’s limited review of the above-referenced Company filing (the “Comment Letter”). The Company hereby submits its responses to the Staff’s comments contained in the Comment Letter, as set forth below. For
the convenience of the Staff, the Staff’s comment has been reproduced below and is set forth in italics immediately prior to the Company’s response.

 Securities and Exchange Commission

 October 19, 2006

 Page 2

 Form 10-K filed March 6, 2006

 Consolidated Statements of Income, page 57

1.
We note your response to comment 2 from our letter dated August 3, 2006. Please tell us how you considered the guidance in EITF 99-19 to support your presentation of
securities lending expense as a reduction of total revenues to arrive at net revenues. We continue to believe that securities lending expense should be presented within your expenses in your income statement rather than as a reduction of revenues in
accordance with Article 5 of Regulation S-K.

 Response:

 As discussed in our teleconference with SEC staff members, including John Spitz, on Tuesday, October 17, 2006, securities lending interest revenue
and expense are peripheral to our core business operations. While these items have been disclosed individually in the current income statement format, in response to the questions raised during this comment process, we are proposing to move this
revenue and expense to non-operating income and expense, respectively. In our response, dated August 31, 2006, to your first comment letter, in Question 2 we stipulated that investment income and the operating results of the unconsolidated
subsidiaries were immaterial. However, to achieve consistent reporting of all non-operating items, we are also proposing to move these items to non-operating income. Making these proposed changes will address the comments related to our presentation
as it relates to Article 5 of Regulation S-X.

 Since all material information relating to these activities has been disclosed to investors
in previous filings and this change relates only to the presentation of certain income statement information, our plan is to make this change prospectively. This would include making the appropriate reclassifications to prior period income
statements in future filings. It is our intent to make these changes effective with our earnings release scheduled to be released on October 24th and in our Form 10-Q for the three month period ended September 30, 2006. For purposes of clarity, we have attached the proposed format displaying 2005 information in Exhibit A.

 Securities and Exchange Commission

 October 19, 2006

 Page 3

 If the Staff has any questions, concerns or additional comments regarding the foregoing or requires
additional information, please contact Nancy Goble, Managing Director and Chief Accounting Officer, at (312) 930-2385. Facsimile transmissions may be sent to the undersigned at (312) 930-4556.

Very truly yours,

CHICAGO MERCANTILE EXCHANGE HOLDINGS INC.

Name:

Kathleen M. Cronin

Title:

Managing Director, General Counsel and Corporate Secretary

 Securities and Exchange Commission

 October 19, 2006

 Page 4

 EXHIBIT A

 Income Statement with Non-Operating Items Presented Separately

2005

 Revenues

 Clearing and transaction fees

$
696,201

 Processing services

68,730

 Quotation data fees

71,741

 Access fees

18,866

 Communication fees

8,964

 Other

25,264

 Total Revenues

889,766

 Expenses

 Compensation and benefits

179,594

 Communications

31,098

 Technology support services

26,837

 Professional fees and outside services

26,850

 Depreciation and amortization

64,917

 Occupancy

28,529

 Licensing and other fee agreements

17,982

 Marketing, advertising and public relations

13,278

 Other

23,054

 Total Expenses

412,139

 Operating Income

477,627

 Non-Operating Income and Expense

 Investment income

31,441

 Securities lending interest income

58,725

 Securities lending interest expense

(56,778
)

 Equity in losses of unconsolidated subsidiaries

(2,636
)

 Total Non-Operating

30,752

 Income before Income Taxes

508,379

 Income tax provision

(201,522
)

 Net Income

$
306,857

October 3, 2006

Mail Stop 4561

Mr. Craig S. Donohue
Chief Executive Officer and Director
Chicago Mercantile Exchange Holdings Inc.
20 South Wacker Drive
Chicago, Illinois 60606

Re: Chicago Mercantile Exchange Holdings Inc.
 Form 10-K for Fiscal Year Ended December 31, 2005
 Filed March 6, 2006
 File Number: 000-33379

Dear Mr. Donohue:

We have reviewed your response to ou r comment letter dated August 3, 2006 and
have the following comment.  Where i ndicated, we think you should revise your
document in response to this comment. If you disagree, we will consider your
explanation as to why our comment is inappli cable or a revision is unnecessary. Please be
as detailed as necessary in your explanation.  In our comment, we may ask you to provide
us with supplemental information so we ma y better understand your disclosure.  After
reviewing this information, we may or  may not raise additional comments.

 Please understand that the purpose of our re view process is to assist you in your
compliance with the applicable disclosure requirements and to enhance the overall
disclosure in your filing.  We look forward to  working with you in these respects.  We
welcome any questions you may have about our comment or any other aspect of our review.  Feel free to call us at the telephone numbers listed at the end of this letter.

Mr. Craig S. Donohue
Chicago Mercantile Exchange Holdings Inc.
October 3, 2006
Page 2

Form 10-K, filed March 6, 2006

Consolidated Statements of Income, page 57
1. We note your response to comment 2 from our letter dated August 3, 2006. Please tell us how you considered the guidance in EITF 99-19 to support your presentation of securities lending expense as a reduction of total revenues to arrive at net revenues. We continue to  believe that securities lending expense
should be presented within your expenses in  your income statement rather than as
a reduction of revenues in accordance w ith Article 5 of Regulation S-X.

* * * * *

As appropriate, please respond to this comm ent within 10 business days or tell us
when you will provide us with a response.  Please furnish a cover letter that keys your response to our comment and provides any re quested supplemental information.  Detailed
cover letters greatly facilitate  our review.  Please understand that we may have additional
comments after reviewing your  response to our comment.

  You may contact John Spitz, Staff Acc ountant at (202) 551-3484, or me at (202)
551-3490, if you have questions re garding these comments.

Sincerely,

Don Walker
Senior Assistant Chief Accountant

CORRESP
1
filename1.htm

Correspondence Letter

 August 31, 2006

 VIA
EDGAR TRANSMISSION AND FACSIMILE

 Securities and Exchange Commission

 Division of Corporate Finance

 450 Fifth Street, N.W.

 Washington, D.C. 20549

 Mail Stop 4561

Attention:
Don Walker, Senior Assistant Chief Accountant

                     John Spitz, Staff Accountant

RE:
Chicago Mercantile Exchange Holdings Inc.

Form 10-K for the year ended December 31, 2005

Filed March 6, 2006

File No. 000-33379

 Ladies and
Gentlemen:

 Chicago Mercantile Exchange Holdings Inc. (the “Company”) has received and reviewed the comments from the staff of the
Division of Corporate Finance (the “Staff”) of the Securities and Exchange Commission (the “Commission”) contained in a letter from Don Walker, Senior Assistant Chief Accountant, dated August 3, 2006, regarding the
Commission’s limited review of the above-referenced Company filing (the “Comment Letter”). The Company hereby submits its responses to the Staff’s comments contained in the Comment Letter, as set forth below. For the convenience
of the Staff, each of the Staff’s comments has been reproduced below and is set forth in italics immediately prior to the Company’s response.

 Securities and Exchange Commission

 August 31, 2006

 Page 2

 Form 10-K filed
March 6, 2006

 Exhibit 13.1

 Liquidity and Cash Management, page 49

1.
We note your disclosure that cash performance bonds and security deposits are included in your consolidated balance sheets and also that with the exception of the portion of
securities deposited that are utilized in your securities lending program, clearing firm deposits other than those retained in the form of cash are not included in your consolidated balance sheets. Please tell us how you differentiate between
including or excluding cash performance bonds, security deposits, and non-cash deposits (primarily short-term U.S. Treasury securities as disclosed in footnote 2 on page 61) in your balance sheet and provide the authoritative guidance to support
your accounting.

 Response: Securities deposited to satisfy performance bond and security deposit requirements are
not included as assets in our consolidated balance sheets. According to FASB Concept Statement No. 6 par. 26, one of three essential characteristics of an asset is that “a particular entity can obtain the [probable future] benefit and
control others’ access to it [the benefit].” Interest and gains or losses on securities deposited accrue only to the clearing firm that has deposited the security with CME. The clearing firms obtain the probable future benefit - interest
and gains or losses on disposal - from the securities they deposit. Cash deposited to satisfy performance bond and security deposit requirements is included as an asset in our consolidated balance sheets because we retain the interest collected.

 Consolidated Statements of Income, page 57

2.
We note that you do not present operating and non-operating income and expenses separately, nor do you present cost of revenues as addressed in Article 5-03(2) of Regulation S-X.
Please tell us:

•

how your statement of income presentation complies with Article 5-03 of Regulation S-X; and

•

why you have netted securities lending interest expense against revenues instead of treating it as a cost of revenues.

 Response:

 Article 5-03(7) of
Regulation S-X requires companies to state separately in the income statement or in a note thereto amounts earned from (a) dividends, (b) interest on securities, (c) profits on securities (net of losses), and (d) miscellaneous
other income. Amounts earned from these sources accounted for 2%, 1% and 0% of total revenues in 2005, 2004 and 2003. Amounts earned from these sources accounted for 4%, 1% and (1)% of pre-tax income in 2005, 2004 and 2003. Under the current
circumstances, we consider these amounts immaterial and do not believe that presenting these items separately on the income statement would increase an investor’s understanding of our financial performance.

 Securities and Exchange Commission

 August 31, 2006

 Page 3

 Article
5-03(2) of Regulation S-X requires companies to state separately the amount of cost of services. We believe that approximately 85% of our expenses are considered directly related to the creation of our revenues. These expenses consist primarily of
non-variable direct expenses and, to a lesser extent, variable direct expenses including license fees paid for the trading of our equity index contracts and a component of our trading facility rent. We believe that the current income statement
presentation is the most meaningful way to convey the results of our operations to investors since the vast majority of our expenses share a similar characterization related to revenue generation.

 Securities lending interest income and expense vary significantly from period to period; however, this variability is not directly related to changes in
our trading volume. Securities lending interest income as a percentage of total revenues was 6%, 3% and 2% in 2005, 2004 and 2003, respectively. Securities lending interest expense as a percentage of total expenses (including securities lending
interest expense) was 12%, 5% and 3% in 2005, 2004 and 2003. However, securities lending interest income, net of related expense, was 0.4% of pre-tax income in all three years. Because securities lending interest expense varies directly with and in
proportion to securities lending interest income, it is presented as a reduction of total revenues to arrive at net revenues.

3.
Please tell us how you determined individually that investment income and each element of other revenues:

•

were the result of central or core operations and not peripheral as addressed in paragraphs 78-89 of FASB Concept Statement 6; and

•

were not non-operating income or expense to be classified separately and addressed in Article 5-03(7)-(9) of Regulation S-X.

 Response: Article 5-03(7) of Regulation S-X requires companies to state separately in the income statement or in a note thereto amounts earned from
(a) dividends, (b) interest on securities, (c) profits on securities (net of losses), and (d) miscellaneous other income. Amounts earned from these sources accounted for 2%, 1% and 0% of total revenues in 2005, 2004 and 2003.
Amounts earned from these sources accounted for 4%, 1% and (1)% of pre-tax income in 2005, 2004 and 2003. Under the current circumstances, we consider these amounts immaterial and do not believe that presenting these items separately on the income
statement would increase an investor’s understanding of our financial performance.

 Securities and Exchange Commission

 August 31, 2006

 Page 4

4.
Please tell us how you determined that each element of “other expense,” as well as other expense line items, should not be classified as selling, general, and
administrative expenses as addressed in Article 5-03(4) of Regulation S-X.

 Response: Articles 5-03(a) and 5-03(4)
of Regulation S-X indicate the various line items which, if applicable, and except as otherwise permitted by the Commission, should appear on the face of the income statement, including selling, general and administrative expenses. Currently, our
income statement presents separately selling, general and administrative categories greater than 5% of net income. We consider remaining amounts immaterial and believe that the current income statement presentation is more meaningful than an
aggregate presentation of selling, general and administrative expenses.

 Acknowledgement

 In connection with the Company’s response to the Staff’s comments, the Company hereby acknowledges that:

•
The Company is responsible for the adequacy and accuracy of the disclosure in its filings;

•
Staff comments or changes to disclosure in response to Staff comments do not foreclose the Commission from taking any action with respect to the filing; and

•
The Company may not assert Staff comments as a defense in any proceeding initiated by the Commission or any person under the federal securities laws of the United States.

 If the Staff has any questions, concerns or additional comments regarding the foregoing or requires additional information,
please contact Nancy Goble, Managing Director and Chief Accounting Officer, at (312) 930-2385. Facsimile transmissions may be sent to the undersigned at (312) 930-4556.

Very truly yours,

CHICAGO MERCANTILE EXCHANGE HOLDINGS INC.

 /s/ Kathleen M. Cronin

Kathleen M. Cronin

 Managing Director, General Counsel and

 Corporate
Secretary

August 3, 2006

Mail Stop 4561

Mr. Craig S. Donohue
Chief Executive Officer and Director
Chicago Mercantile Exchange Holdings Inc.
20 South Wacker Drive
Chicago, Illinois 60606

Re: Chicago Mercantile Exchange Holdings Inc.
 Form 10-K for Fiscal Year Ended December 31, 2005
 Filed March 6, 2006
 File Number: 000-33379

Dear Mr. Donohue:

We have reviewed filing and have the following comments.  Where indicated, we
think you should revise your document in resp onse to these comments. If you disagree,
we will consider your explanation as to why our comments are inapplicable or a revision
is unnecessary. Please be as detailed as necessa ry in your explanation.  In our comments,
we may ask you to provide us with suppl emental information so we may better
understand your disclosure.  After reviewing th is information, we may or may not raise
additional comments.

 Please understand that the purpose of our re view process is to assist you in your
compliance with the applicable disclosure requirements and to enhance the overall
disclosure in your filing.  We look forward to  working with you in these respects.  We
welcome any questions you may have about our comments or any other aspect of our review.  Feel free to call us at the telephone numbers listed at the end of this letter.

Mr. Craig S. Donohue
Chicago Mercantile Exchange Holdings Inc.
August 3, 2006
Page 2

Form 10-K, filed March 6, 2006

Exhibit 13.1

Liquidity and Cash Management, page 49
1. We note your disclosure that cash pe rformance bonds and security deposits are
included in your consolidated balance sheet s and also that wi th the exception of
the portion of securities deposited that are utilized in your securities lending
program, clearing firm deposits other than t hose retained in the form of cash are
not included in your consolidated ba lance sheets. Please tell us how you
differentiate between including or excl uding cash performance bonds, security
deposits, and non-cash deposits (primarily s hort-term U.S. Treasury securities as
disclosed in footnote 2 on page 61) in your balance sheet and provide the
authoritative guidance to support your accounting.

Consolidated Statements of Income, page 57
2. We note that you do not present oper ating and non-operating income and
expenses separately, nor do you present cost  of revenues as addressed in Article
5-03(2) of Regulation S-X. Please tell us:

• how your statement of income presentation complies with Article 5-03 of Regulation S-X; and
• why you have netted secu rities lending interest expense against revenues
instead of treating it as a cost of revenues.
3. Please tell us how you determined indivi dually that investment income and each
element of other revenues:

• were the result of central or core opera tions and not peripheral as addressed in
paragraphs 78-89 of FASB Concept Statement 6; and
• were not non-operating income or expens e to be classified separately and
addressed in Article 5-03(7 )-(9) of Regulation S-X.
4. Please tell us how you determined that each  element of “other expense,” as well
as other expense line items, should not be  classified as selling, general, and
administrative expenses as addressed in  Article 5-03(4) of Regulation S-X.

Mr. Craig S. Donohue
Chicago Mercantile Exchange Holdings Inc.
August 3, 2006
Page 3

* * * * *

As appropriate, please respond to these co mments within 10 business days or tell
us when you will provide us with a response.  Pl ease furnish a cover letter that keys your
responses to our comments and provides any requested supplemental information.
Detailed cover letters greatly facilitate our review.  Please understa nd that we may have
additional comments after reviewin g your response to our comments.

  We urge all persons who are responsi ble for the accuracy an d adequacy of the
disclosure in the filing review ed by the staff to be certain that they have provided all
information investors require for an inform ed decision.  Since the company and its
management are in possession of all facts re lating to a company’s disclosure, they are
responsible for the accuracy and adequacy of the disclosures they have made.

 In connection with responding to our comments, please provide, in writing, a statement from the company acknowledging that:

‚ the company is responsible for the adequacy  and accuracy of the disclosure in the
filing;

‚ staff comments or changes to disclosure  in response to staff comments do not
foreclose the Commission from taking any action with respect to the filing; and

‚ the company may not assert staff comme nts as a defense in any proceeding
initiated by the Commission or any person under the federal secu rities laws of the
United States.

In addition, please be advise d that the Division of Enfo rcement has access to all
information you provide to the staff of the Divi sion of Corporation Fi nance in our review
of your filing or in response to our comments on your filing.

You may contact John Spitz, Staff Accountant at (202) 551-3484, or me at (202)
551-3490, if you have questions re garding these comments.

Sincerely,

Don Walker
Senior Assistant Chief Accountant