SecProbe.io

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)