<?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:ns2="http://www.sec.gov/edgar/common">
    <headerData>
        <submissionType>144</submissionType>
        <filerInfo>
            <filer>
                <filerCredentials>
                    <cik>0001952996</cik>
                    <ccc>XXXXXXXX</ccc>
                </filerCredentials>
            </filer>
            <liveTestFlag>LIVE</liveTestFlag>



        </filerInfo>
    </headerData>
    <formData>
        <issuerInfo>
            <issuerCik>0001156375</issuerCik>
            <issuerName>CME GROUP INC.</issuerName>
            <secFileNumber>001-31553</secFileNumber>
            <issuerAddress>
                <ns2:street1>20 South Wacker Drive</ns2:street1>
                <ns2:city>Chicago</ns2:city>
                <ns2:stateOrCountry>IL</ns2:stateOrCountry>
                <ns2:zipCode>60606</ns2:zipCode>
            </issuerAddress>
            <issuerContactPhone>(312) 930-1000</issuerContactPhone>
            <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>JONATHAN MARCUS</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
            <relationshipsToIssuer>
                <relationshipToIssuer>Officer</relationshipToIssuer>
            </relationshipsToIssuer>
        </issuerInfo>
        <securitiesInformation>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <brokerOrMarketmakerDetails>
                <name>Morgan Stanley Smith Barney LLC Executive Financial Services</name>
                <address>
                    <ns2:street1>1 New York Plaza</ns2:street1>
                    <ns2:street2>8th Floor</ns2:street2>
                    <ns2:city>New York</ns2:city>
                    <ns2:stateOrCountry>NY</ns2:stateOrCountry>
                    <ns2:zipCode>10004</ns2:zipCode>
                </address>
            </brokerOrMarketmakerDetails>
            <noOfUnitsSold>390</noOfUnitsSold>
            <aggregateMarketValue>108225.00</aggregateMarketValue>
            <noOfUnitsOutstanding>360356107</noOfUnitsOutstanding>
            <approxSaleDate>05/20/2025</approxSaleDate>
            <securitiesExchangeName>NASDAQ</securitiesExchangeName>
        </securitiesInformation>
        <securitiesToBeSold>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <acquiredDate>03/15/2025</acquiredDate>
            <natureOfAcquisitionTransaction>Restricted Stock</natureOfAcquisitionTransaction>
            <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
            <isGiftTransaction>N</isGiftTransaction>
            <amountOfSecuritiesAcquired>390</amountOfSecuritiesAcquired>
            <paymentDate>03/15/2025</paymentDate>
            <natureOfPayment>Not Applicable</natureOfPayment>
        </securitiesToBeSold>
        <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
        <noticeSignature>
            <noticeDate>05/20/2025</noticeDate>
            <planAdoptionDates>
                <planAdoptionDate>02/18/2025</planAdoptionDate>
            </planAdoptionDates>
            <signature>/s/ Jonathan Marcus</signature>
        </noticeSignature>
    </formData>
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144
0001952996
XXXXXXXX
LIVE
0001156375
CME GROUP INC.
001-31553
20 South Wacker Drive
Chicago
IL
60606
(312) 930-1000
JONATHAN MARCUS
Officer
Common
Morgan Stanley Smith Barney LLC Executive Financial Services
1 New York Plaza
8th Floor
New York
NY
10004
390
108225.00
360356107
05/20/2025
NASDAQ
Common
03/15/2025
Restricted Stock
Issuer
N
390
03/15/2025
Not Applicable
Y
05/20/2025
02/18/2025
/s/ Jonathan Marcus