<SEC-DOCUMENT>0001156375-22-000056.txt : 20220214
<SEC-HEADER>0001156375-22-000056.hdr.sgml : 20220214
<ACCEPTANCE-DATETIME>20220214195310
ACCESSION NUMBER:		0001156375-22-000056
CONFORMED SUBMISSION TYPE:	4/A
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20220125
FILED AS OF DATE:		20220214
DATE AS OF CHANGE:		20220214

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			SIEGEL HOWARD J
		CENTRAL INDEX KEY:			0001212853

	FILING VALUES:
		FORM TYPE:		4/A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-31553
		FILM NUMBER:		22636464

	MAIL ADDRESS:	
		STREET 1:		20 S. WACKER DR
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60606

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			CME GROUP INC.
		CENTRAL INDEX KEY:			0001156375
		STANDARD INDUSTRIAL CLASSIFICATION:	SECURITY & COMMODITY BROKERS, DEALERS, EXCHANGES & SERVICES [6200]
		IRS NUMBER:				364459170
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		20 S. WACKER DR.
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60606
		BUSINESS PHONE:		3129301000

	MAIL ADDRESS:	
		STREET 1:		20 S. WACKER DR.
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60606

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	CHICAGO MERCANTILE EXCHANGE HOLDINGS INC
		DATE OF NAME CHANGE:	20010802
</SEC-HEADER>
<DOCUMENT>
<TYPE>4/A
<SEQUENCE>1
<FILENAME>wf-form4a_164488635775495.xml
<DESCRIPTION>FORM 4/A
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2022-01-25</periodOfReport>

    <dateOfOriginalSubmission>2022-01-26</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001156375</issuerCik>
        <issuerName>CME GROUP INC.</issuerName>
        <issuerTradingSymbol>CME</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001212853</rptOwnerCik>
            <rptOwnerName>SIEGEL HOWARD J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>20 S. WACKER DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CHICAGO</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60606</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock Class A</value>
            </securityTitle>
            <transactionDate>
                <value>2022-01-25</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>75</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>221.79</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>43187</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock Class A</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>31873</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>by Trust</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Granted pursuant to the CME Group Director Stock Plan, as amended and restated.</footnote>
        <footnote id="F2">The original Form 4 filed on January 26, 2022 incorrectly reported 75,060 shares held directly by Mr. Siegel.  This amendment is being filed to correctly report the amount as 43,187 shares held directly by Mr. Siegel.</footnote>
        <footnote id="F3">The original Form 4 filed on January 26, 2022 did not reflect Mr. Siegel's indirect holdings.  This amendment is being filed to correctly report the amount as 31,873 shares held indirectly by Mr. Siegel's Trust.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>By: Margaret Austin Wright For: Howard J. Siegel</signatureName>
        <signatureDate>2022-02-14</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
