content: <?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>0001329150</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>Lucas Deborah J</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>1500</noOfUnitsSold>
        <aggregateMarketValue>388500.00</aggregateMarketValue>
        <noOfUnitsOutstanding>360354174</noOfUnitsOutstanding>
        <approxSaleDate>03/14/2025</approxSaleDate>
        <securitiesExchangeName>NASDAQ</securitiesExchangeName>
      </securitiesInformation>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>01/25/2022</acquiredDate>
        <natureOfAcquisitionTransaction>Stock Award</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>ISSUER</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>47</amountOfSecuritiesAcquired>
        <paymentDate>01/25/2022</paymentDate>
        <natureOfPayment>Compensation</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>06/25/2021</acquiredDate>
        <natureOfAcquisitionTransaction>Stock Award</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>ISSUER</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>551</amountOfSecuritiesAcquired>
        <paymentDate>06/25/2021</paymentDate>
        <natureOfPayment>Compensation</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>06/27/2022</acquiredDate>
        <natureOfAcquisitionTransaction>Stock Award</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>ISSUER</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>693</amountOfSecuritiesAcquired>
        <paymentDate>06/27/2022</paymentDate>
        <natureOfPayment>Compensation</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>06/26/2023</acquiredDate>
        <natureOfAcquisitionTransaction>Stock Award</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>ISSUER</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>209</amountOfSecuritiesAcquired>
        <paymentDate>06/26/2023</paymentDate>
        <natureOfPayment>Compensation</natureOfPayment>
      </securitiesToBeSold>
      <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
      <noticeSignature>
        <noticeDate>03/14/2025</noticeDate>
        <signature>/s/ Jordyn Davis as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Lucas Deborah J </signature>
      </noticeSignature>
    </formData>
  </edgarSubmission>
metadata_documents: [{"type": "144", "sequence": "1", "filename": "primary_doc.xml", "secsgml_size_bytes": 4376}]
text: 144
  0001329150
  XXXXXXXX
  LIVE
  0001156375
  CME GROUP INC.
  001-31553
  20 S. WACKER DR.
  CHICAGO
  IL
  60606
  3129301000
  Lucas Deborah J
  Director
  Common
  FIDELITY BROKERAGE SERVICES LLC
  245 Summer Street
  BOSTON
  MA
  02110
  1500
  388500.00
  360354174
  03/14/2025
  NASDAQ
  Common
  01/25/2022
  Stock Award
  ISSUER
  N
  47
  01/25/2022
  Compensation
  Common
  06/25/2021
  Stock Award
  ISSUER
  N
  551
  06/25/2021
  Compensation
  Common
  06/27/2022
  Stock Award
  ISSUER
  N
  693
  06/27/2022
  Compensation
  Common
  06/26/2023
  Stock Award
  ISSUER
  N
  209
  06/26/2023
  Compensation
  Y
  03/14/2025
  /s/ Jordyn Davis as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Lucas Deborah J