SecProbe.io

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