CME (CME) DEFA14A Additional proxy soliciting materials

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a)

of the Securities Exchange Act of 1934

(Amendment No.     )

Filed by the Registrant  ☒

Filed by a Party other than the Registrant  ☐

Check the appropriate box:

☐	Preliminary Proxy Statement	☐	Confidential, for Use of the Commission Only (as permitted by Rule14a-6(e)(2))
☐	Definitive Proxy Statement
☒	Definitive Additional Materials
☐	Soliciting Material Pursuant to§240.14a-12

CME GROUP INC.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

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☐ Fee computed on table below per Exchange Act Rules14a-6(i)(1) and0-11.

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☐ Fee paid previously with preliminary materials.

☐ Check box if any part of the fee is offset as provided by Exchange Act Rule0-11(a)(2) and identify the filing for which the offsetting fee was paid previously. Identify the previous filing by registration statement number, or the Form or Schedule and the date of its filing.

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(2) Form, Schedule or Registration Statement No.:

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(4) Date Filed:

*** Exercise Your Right to Vote *** Important Notice Regarding the Availability of Proxy Materials for the Shareholder Meeting to Be Held on November 5, 2018. Meeting Information CME GROUP INC. Meeting Type: Special Meeting For holders as of: September 6, 2018 Date: November 5, 2018 Time: 10:00 a.m., Central Time Location: CME Group Headquarters 20 South Wacker Drive Chicago, IL 60606 You are receiving this communication because you hold shares in the company named above. This is not a ballot. You cannot use this notice to vote these shares. This communication presents only an overview of the more complete proxy materials that are available to you on the Internet. You may view the proxy materials online at www.proxyvote.com, scan the QR Barcode on the reverse side, or easily request a paper copy (see reverse side). We encourage you to access and review all of the important information contained in the proxy materials before voting. S75247 proxy See the materials reverse and side voting of this instructions. notice to obtain E50774—

Before You Vote How to Access the Proxy Materials Proxy Materials Available to VIEW or RECEIVE: NOTICE AND PROXY STATEMENT How to View Online: Have the information that is printed in the box marked by the arrow ï§XXXX XXXX XXXX XXXX (located on the following page) and visit: www.proxyvote.com, or scan the QR Barcode below. How to Request and Receive a PAPER orE-MAIL Copy: If you want to receive a paper ore-mail copy of these documents, you must request one. There is NO charge for requesting a copy. Please choose one of the following methods to make your request: 1) BY INTERNET: www.proxyvote.com 2) BY TELEPHONE:1-800-579-1639 3) BYE-MAIL*: sendmaterial@proxyvote.com * If requesting materials by e mail, please send a blank e mail with the information that is printed in the box marked by the arrowï§XXXX XXXX XXXX XXXX (located on the following page) in the subject line. Requests, instructions and other inquiries sent to thise-mail address will NOT be forwarded to your investment advisor. Please make the request as instructed above on or before October 22, 2018 to facilitate timely delivery. How To Vote SCAN TO VIEW MATERIALS & VOTE w Please Choose One of the Following Voting Methods Vote In Person: If you choose to vote these shares in person at the meeting, you must request a “legal proxy.” To do so, please follow the instructions at www.proxyvote.com or request a paper copy of the materials, which will contain the appropriate instructions. Many shareholder meetings have attendance requirements including, but not limited to, the possession of an attendance ticket issued by the entity holding the meeting. Please check the meeting materials for any special requirements for meeting attendance. Vote By Internet: Go to www.proxyvote.com or from a smart phone, scan the QR Barcode above. Have the information that is printed in the box marked by the arrowï§XXXX XXXX XXXX XXXX (located on the following page) available and follow the instructions. S75247 Vote By Mail: You can vote by mail by requesting a paper copy of the materials, which will include a voting instruction form. - Shareholder Meeting Registration: To attend the CME Group special meeting, please go to the“Register for Meeting” link at www.proxyvote.com E50775 and follow the instructions provided. You will need the 16 digit number located on the following page. Please print your registration confirmation and bring it with you to the meeting along with valid picture identification.

Voting Items The Board of Directors recommends you vote FOR the following proposal: 1. Approve an amendment and restatement of our certificate of incorporation to eliminate all or some of the Class B Election Rights. NOTE: Such other business as may properly come before the meeting or any adjournment thereof. - S75247 E50776

Voting Instructions - S75247 E50777