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    <filerInfo>
      <filer>
        <filerCredentials>
          <cik>0001247069</cik>
          <ccc>XXXXXXXX</ccc>
        </filerCredentials>
      </filer>
      <liveTestFlag>LIVE</liveTestFlag>



    </filerInfo>
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  <formData>
    <issuerInfo>
      <issuerCik>0000029989</issuerCik>
      <issuerName>OMNICOM GROUP INC.</issuerName>
      <secFileNumber>001-10551</secFileNumber>
      <issuerAddress>
        <com:street1>280 PARK AVENUE</com:street1>
        <com:city>NEW YORK</com:city>
        <com:stateOrCountry>NY</com:stateOrCountry>
        <com:zipCode>10017</com:zipCode>
      </issuerAddress>
      <issuerContactPhone>2124153600</issuerContactPhone>
      <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>WREN JOHN</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
      <relationshipsToIssuer>
        <relationshipToIssuer>Officer</relationshipToIssuer>
      </relationshipsToIssuer>
    </issuerInfo>
    <securitiesInformation>
      <securitiesClassTitle>COMMON</securitiesClassTitle>
      <brokerOrMarketmakerDetails>
        <name>FIDELITY BROKERAGE SERVICES, LLC</name>
        <address>
          <com:street1>900 Salem STREET</com:street1>
          <com:city>SMITHFIELD</com:city>
          <com:stateOrCountry>RI</com:stateOrCountry>
          <com:zipCode>02917</com:zipCode>
        </address>
      </brokerOrMarketmakerDetails>
      <noOfUnitsSold>100000</noOfUnitsSold>
      <aggregateMarketValue>9384020.50</aggregateMarketValue>
      <noOfUnitsOutstanding>199514755</noOfUnitsOutstanding>
      <approxSaleDate>04/24/2023</approxSaleDate>
      <securitiesExchangeName>NYSE</securitiesExchangeName>
    </securitiesInformation>
    <securitiesToBeSold>
      <securitiesClassTitle>COMMON</securitiesClassTitle>
      <acquiredDate>06/16/2015</acquiredDate>
      <natureOfAcquisitionTransaction>Restricted Stock Vesting</natureOfAcquisitionTransaction>
      <nameOfPersonfromWhomAcquired>ISSUER</nameOfPersonfromWhomAcquired>
      <isGiftTransaction>N</isGiftTransaction>
      <amountOfSecuritiesAcquired>54046</amountOfSecuritiesAcquired>
      <paymentDate>06/16/2015</paymentDate>
      <natureOfPayment>Compensation</natureOfPayment>
    </securitiesToBeSold>
    <securitiesToBeSold>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <acquiredDate>11/10/2010</acquiredDate>
      <natureOfAcquisitionTransaction>Stock Option Exercised</natureOfAcquisitionTransaction>
      <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
      <isGiftTransaction>N</isGiftTransaction>
      <amountOfSecuritiesAcquired>45954</amountOfSecuritiesAcquired>
      <paymentDate>11/10/2010</paymentDate>
      <natureOfPayment>Cash</natureOfPayment>
    </securitiesToBeSold>
    <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
    <noticeSignature>
      <noticeDate>04/24/2023</noticeDate>
      <signature>/s/Wade Moss, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for John Wren</signature>
    </noticeSignature>
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144
0001247069
XXXXXXXX
LIVE
0000029989
OMNICOM GROUP INC.
001-10551
280 PARK AVENUE
NEW YORK
NY
10017
2124153600
WREN JOHN
Officer
COMMON
FIDELITY BROKERAGE SERVICES, LLC
900 Salem STREET
SMITHFIELD
RI
02917
100000
9384020.50
199514755
04/24/2023
NYSE
COMMON
06/16/2015
Restricted Stock Vesting
ISSUER
N
54046
06/16/2015
Compensation
Common
11/10/2010
Stock Option Exercised
Issuer
N
45954
11/10/2010
Cash
Y
04/24/2023
/s/Wade Moss, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for John Wren