<?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:com="http://www.sec.gov/edgar/common">
  <headerData>
    <submissionType>144</submissionType>
    <filerInfo>
      <filer>
        <filerCredentials>
          <cik>0001475318</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>
        <com:street1>20 S. WACKER DR.</com:street1>
        <com:city>CHICAGO</com:city>
        <com:stateOrCountry>IL</com:stateOrCountry>
        <com:zipCode>60606</com:zipCode>
      </issuerAddress>
      <issuerContactPhone>3129301000</issuerContactPhone>
      <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>Sammann Derek</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
      <relationshipsToIssuer>
        <relationshipToIssuer>Officer</relationshipToIssuer>
      </relationshipsToIssuer>
    </issuerInfo>
    <securitiesInformation>
      <securitiesClassTitle>Class A</securitiesClassTitle>
      <brokerOrMarketmakerDetails>
        <name>Charles Schwab Corp.</name>
        <address>
          <com:street1>3000 Schwab Way</com:street1>
          <com:city>Westlake</com:city>
          <com:stateOrCountry>TX</com:stateOrCountry>
          <com:zipCode>76262</com:zipCode>
        </address>
      </brokerOrMarketmakerDetails>
      <noOfUnitsSold>4650</noOfUnitsSold>
      <aggregateMarketValue>1307580.00</aggregateMarketValue>
      <noOfUnitsOutstanding>360356107</noOfUnitsOutstanding>
      <approxSaleDate>05/02/2025</approxSaleDate>
      <securitiesExchangeName>Nasdaq</securitiesExchangeName>
    </securitiesInformation>
    <securitiesToBeSold>
      <securitiesClassTitle>Class A</securitiesClassTitle>
      <acquiredDate>03/15/2025</acquiredDate>
      <natureOfAcquisitionTransaction>Equity Compensation</natureOfAcquisitionTransaction>
      <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
      <isGiftTransaction>N</isGiftTransaction>
      <amountOfSecuritiesAcquired>4650</amountOfSecuritiesAcquired>
      <paymentDate>03/15/2025</paymentDate>
      <natureOfPayment>Equity Compensation</natureOfPayment>
    </securitiesToBeSold>
    <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
    <remarks>2,475 shares to be sold from the Elizabeth Sammann 1999 Trust, Derek L Sammann Trustee. 2,175 shares to be sold from the Derek Samman 1999 Trust, Derek L Sammann Trustee.</remarks>
    <noticeSignature>
      <noticeDate>05/02/2025</noticeDate>
      <signature>Derek Sammann</signature>
    </noticeSignature>
  </formData>
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144
0001475318
XXXXXXXX
LIVE
0001156375
CME GROUP INC.
001-31553
20 S. WACKER DR.
CHICAGO
IL
60606
3129301000
Sammann Derek
Officer
Class A
Charles Schwab Corp.
3000 Schwab Way
Westlake
TX
76262
4650
1307580.00
360356107
05/02/2025
Nasdaq
Class A
03/15/2025
Equity Compensation
Issuer
N
4650
03/15/2025
Equity Compensation
Y
2,475 shares to be sold from the Elizabeth Sammann 1999 Trust, Derek L Sammann Trustee. 2,175 shares to be sold from the Derek Samman 1999 Trust, Derek L Sammann Trustee.
05/02/2025
Derek Sammann