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>0001212853</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>SIEGEL HOWARD J</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
        <relationshipsToIssuer>
          <relationshipToIssuer>Director</relationshipToIssuer>
        </relationshipsToIssuer>
      </issuerInfo>
      <securitiesInformation>
        <securitiesClassTitle>Common Stock</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>20000</noOfUnitsSold>
        <aggregateMarketValue>5113400.00</aggregateMarketValue>
        <noOfUnitsOutstanding>360354174</noOfUnitsOutstanding>
        <approxSaleDate>03/12/2025</approxSaleDate>
        <securitiesExchangeName>nasdaq</securitiesExchangeName>
      </securitiesInformation>
      <securitiesToBeSold>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <acquiredDate>06/29/2016</acquiredDate>
        <natureOfAcquisitionTransaction>Stock Grant</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>CME</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>342</amountOfSecuritiesAcquired>
        <paymentDate>06/29/2016</paymentDate>
        <natureOfPayment>Stock Grant</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <acquiredDate>06/25/2015</acquiredDate>
        <natureOfAcquisitionTransaction>Stock Grant</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>CME</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>1064</amountOfSecuritiesAcquired>
        <paymentDate>06/25/2015</paymentDate>
        <natureOfPayment>Stock Grant</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <acquiredDate>08/25/2014</acquiredDate>
        <natureOfAcquisitionTransaction>Stock Grant</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>CME</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>793</amountOfSecuritiesAcquired>
        <paymentDate>08/25/2014</paymentDate>
        <natureOfPayment>Stock Grant</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <acquiredDate>06/25/2014</acquiredDate>
        <natureOfAcquisitionTransaction>Stock Grant</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>CME</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>1415</amountOfSecuritiesAcquired>
        <paymentDate>06/25/2014</paymentDate>
        <natureOfPayment>Stock Grant</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <acquiredDate>06/25/2013</acquiredDate>
        <natureOfAcquisitionTransaction>Stock Grant</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>CME</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>982</amountOfSecuritiesAcquired>
        <paymentDate>06/25/2013</paymentDate>
        <natureOfPayment>Stock Grant</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <acquiredDate>06/25/2012</acquiredDate>
        <natureOfAcquisitionTransaction>Stock grant</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>CME</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>1870</amountOfSecuritiesAcquired>
        <paymentDate>06/25/2012</paymentDate>
        <natureOfPayment>Stock Grant</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <acquiredDate>06/27/2011</acquiredDate>
        <natureOfAcquisitionTransaction>Stock grant</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>CME</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>1335</amountOfSecuritiesAcquired>
        <paymentDate>06/27/2011</paymentDate>
        <natureOfPayment>Stock Grant</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <acquiredDate>05/25/2010</acquiredDate>
        <natureOfAcquisitionTransaction>Stock grant</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>CME</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>1205</amountOfSecuritiesAcquired>
        <paymentDate>05/25/2010</paymentDate>
        <natureOfPayment>Stock Grant</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <acquiredDate>05/26/2009</acquiredDate>
        <natureOfAcquisitionTransaction>Stock grant</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>CME</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>1645</amountOfSecuritiesAcquired>
        <paymentDate>05/26/2009</paymentDate>
        <natureOfPayment>Stock Grant</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <acquiredDate>05/27/2008</acquiredDate>
        <natureOfAcquisitionTransaction>Stock grant</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>CME</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>1105</amountOfSecuritiesAcquired>
        <paymentDate>05/27/2008</paymentDate>
        <natureOfPayment>Stock Grant</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <acquiredDate>05/27/2007</acquiredDate>
        <natureOfAcquisitionTransaction>Stock grant</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>CME</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>975</amountOfSecuritiesAcquired>
        <paymentDate>05/27/2007</paymentDate>
        <natureOfPayment>Stock Grant</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <acquiredDate>08/25/2006</acquiredDate>
        <natureOfAcquisitionTransaction>Stock grant</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>CME</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>325</amountOfSecuritiesAcquired>
        <paymentDate>08/25/2006</paymentDate>
        <natureOfPayment>Stock Grant</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <acquiredDate>05/25/2006</acquiredDate>
        <natureOfAcquisitionTransaction>Stock grant</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>CME</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>705</amountOfSecuritiesAcquired>
        <paymentDate>05/26/2006</paymentDate>
        <natureOfPayment>Stock Grant</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <acquiredDate>05/05/2006</acquiredDate>
        <natureOfAcquisitionTransaction>Stock grant</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>CME</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>915</amountOfSecuritiesAcquired>
        <paymentDate>05/05/2006</paymentDate>
        <natureOfPayment>Stock Grant</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <acquiredDate>06/29/2001</acquiredDate>
        <natureOfAcquisitionTransaction>Initial Shares</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>CME</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>5324</amountOfSecuritiesAcquired>
        <paymentDate>06/29/2001</paymentDate>
        <natureOfPayment>Stock Grant</natureOfPayment>
      </securitiesToBeSold>
      <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
      <remarks>shares are being sold from HOWARD J SIEGEL REVOCABLE TRU U/A 6/12/12 FBO HOWARD J SIEGEL </remarks>
      <noticeSignature>
        <noticeDate>03/12/2025</noticeDate>
        <signature>/s/ Audrey Skillern as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Howard SIEGEL </signature>
      </noticeSignature>
    </formData>
  </edgarSubmission>
metadata_documents: [{"type": "144", "sequence": "1", "filename": "primary_doc.xml", "secsgml_size_bytes": 10304}]
text: 144
  0001212853
  XXXXXXXX
  LIVE
  0001156375
  CME GROUP INC.
  001-31553
  20 S. WACKER DR.
  CHICAGO
  IL
  60606
  3129301000
  SIEGEL HOWARD J
  Director
  Common Stock
  Fidelity Brokerage Services LLC
  245 Summer Street
  Boston
  MA
  02110
  20000
  5113400.00
  360354174
  03/12/2025
  nasdaq
  Common Stock
  06/29/2016
  Stock Grant
  CME
  N
  342
  06/29/2016
  Stock Grant
  Common Stock
  06/25/2015
  Stock Grant
  CME
  N
  1064
  06/25/2015
  Stock Grant
  Common Stock
  08/25/2014
  Stock Grant
  CME
  N
  793
  08/25/2014
  Stock Grant
  Common Stock
  06/25/2014
  Stock Grant
  CME
  N
  1415
  06/25/2014
  Stock Grant
  Common Stock
  06/25/2013
  Stock Grant
  CME
  N
  982
  06/25/2013
  Stock Grant
  Common Stock
  06/25/2012
  Stock grant
  CME
  N
  1870
  06/25/2012
  Stock Grant
  Common Stock
  06/27/2011
  Stock grant
  CME
  N
  1335
  06/27/2011
  Stock Grant
  Common Stock
  05/25/2010
  Stock grant
  CME
  N
  1205
  05/25/2010
  Stock Grant
  Common Stock
  05/26/2009
  Stock grant
  CME
  N
  1645
  05/26/2009
  Stock Grant
  Common Stock
  05/27/2008
  Stock grant
  CME
  N
  1105
  05/27/2008
  Stock Grant
  Common Stock
  05/27/2007
  Stock grant
  CME
  N
  975
  05/27/2007
  Stock Grant
  Common Stock
  08/25/2006
  Stock grant
  CME
  N
  325
  08/25/2006
  Stock Grant
  Common Stock
  05/25/2006
  Stock grant
  CME
  N
  705
  05/26/2006
  Stock Grant
  Common Stock
  05/05/2006
  Stock grant
  CME
  N
  915
  05/05/2006
  Stock Grant
  Common Stock
  06/29/2001
  Initial Shares
  CME
  N
  5324
  06/29/2001
  Stock Grant
  Y
  shares are being sold from HOWARD J SIEGEL REVOCABLE TRU U/A 6/12/12 FBO HOWARD J SIEGEL
  03/12/2025
  /s/ Audrey Skillern as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Howard SIEGEL