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