content: <?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:com="http://www.sec.gov/edgar/common">
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      <submissionType>144</submissionType>
      <filerInfo>
        <filer>
          <filerCredentials>
            <cik>0001556974</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>Kaye Daniel G</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
        <relationshipsToIssuer>
          <relationshipToIssuer>Director</relationshipToIssuer>
        </relationshipsToIssuer>
      </issuerInfo>
      <securitiesInformation>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <brokerOrMarketmakerDetails>
          <name>Fidelity Brokerage Services LLC</name>
          <address>
            <com:street1>245 Summer Street</com:street1>
            <com:city>Boston </com:city>
            <com:stateOrCountry>MA</com:stateOrCountry>
            <com:zipCode>02110</com:zipCode>
          </address>
        </brokerOrMarketmakerDetails>
        <noOfUnitsSold>500</noOfUnitsSold>
        <aggregateMarketValue>141250.00</aggregateMarketValue>
        <noOfUnitsOutstanding>360356107</noOfUnitsOutstanding>
        <approxSaleDate>05/22/2025</approxSaleDate>
        <securitiesExchangeName>NASDAQ</securitiesExchangeName>
      </securitiesInformation>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>05/25/2021</acquiredDate>
        <natureOfAcquisitionTransaction>Stock Award</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>4168</amountOfSecuritiesAcquired>
        <paymentDate>06/25/2021</paymentDate>
        <natureOfPayment>Compensation</natureOfPayment>
      </securitiesToBeSold>
      <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
      <noticeSignature>
        <noticeDate>05/22/2025</noticeDate>
        <signature>/s/ Christian Nasser as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Daniel Kaye</signature>
      </noticeSignature>
    </formData>
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text: 144
  0001556974
  XXXXXXXX
  LIVE
  0001156375
  CME GROUP INC.
  001-31553
  20 S. WACKER DR.
  CHICAGO
  IL
  60606
  3129301000
  Kaye Daniel G
  Director
  Common
  Fidelity Brokerage Services LLC
  245 Summer Street
  Boston
  MA
  02110
  500
  141250.00
  360356107
  05/22/2025
  NASDAQ
  Common
  05/25/2021
  Stock Award
  Issuer
  N
  4168
  06/25/2021
  Compensation
  Y
  05/22/2025
  /s/ Christian Nasser as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Daniel Kaye