content: <?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:com="http://www.sec.gov/edgar/common">
    <!-- Generated by Workiva -->
    <headerData>
      <submissionType>144</submissionType>
      <filerInfo>
        <filer>
          <filerCredentials>
            <cik>0001675872</cik>
            <ccc>XXXXXXXX</ccc>
          </filerCredentials>
        </filer>
        <liveTestFlag>LIVE</liveTestFlag>
  
  
  
      </filerInfo>
    </headerData>
    <formData>
      <issuerInfo>
        <issuerCik>0000860413</issuerCik>
        <issuerName>First Interstate BancSystem, Inc.</issuerName>
        <secFileNumber>001-34653</secFileNumber>
        <issuerAddress>
          <com:street1>401 NO 31ST STREET</com:street1>
          <com:city>BILLINGS</com:city>
          <com:stateOrCountry>MT</com:stateOrCountry>
          <com:zipCode>59101</com:zipCode>
        </issuerAddress>
        <issuerContactPhone>406-255-5311</issuerContactPhone>
        <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>James R. Scott, Jr.</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
        <relationshipsToIssuer>
          <relationshipToIssuer>Affiliate</relationshipToIssuer>
        </relationshipsToIssuer>
      </issuerInfo>
      <securitiesInformation>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <brokerOrMarketmakerDetails>
          <name>J.P. Morgan Securities LLC</name>
          <address>
            <com:street1>390 Madison Avenue - 6th Floor</com:street1>
            <com:city>New York</com:city>
            <com:stateOrCountry>NY</com:stateOrCountry>
            <com:zipCode>10017</com:zipCode>
          </address>
        </brokerOrMarketmakerDetails>
        <noOfUnitsSold>6067</noOfUnitsSold>
        <aggregateMarketValue>208644.13</aggregateMarketValue>
        <noOfUnitsOutstanding>104529863</noOfUnitsOutstanding>
        <approxSaleDate>11/22/2024</approxSaleDate>
        <securitiesExchangeName>Nasdaq</securitiesExchangeName>
      </securitiesInformation>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>12/28/2020</acquiredDate>
        <natureOfAcquisitionTransaction>Gift</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>James and Christine Scott</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>Y</isGiftTransaction>
        <donarAcquiredDate>12/06/1971</donarAcquiredDate>
        <amountOfSecuritiesAcquired>6067</amountOfSecuritiesAcquired>
        <natureOfPayment>N/A</natureOfPayment>
      </securitiesToBeSold>
      <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
      <noticeSignature>
        <noticeDate>11/22/2024</noticeDate>
        <signature>/s/ J.P. Morgan Securities LLC as agent and attorney-in-fact for James R, Scott Jr.</signature>
      </noticeSignature>
    </formData>
  </edgarSubmission>
metadata_documents: [{"type": "144", "sequence": "1", "filename": "primary_doc.xml", "secsgml_size_bytes": 2853}]
text: 144
  0001675872
  XXXXXXXX
  LIVE
  0000860413
  First Interstate BancSystem, Inc.
  001-34653
  401 NO 31ST STREET
  BILLINGS
  MT
  59101
  406-255-5311
  James R. Scott, Jr.
  Affiliate
  Common Stock
  J.P. Morgan Securities LLC
  390 Madison Avenue - 6th Floor
  New York
  NY
  10017
  6067
  208644.13
  104529863
  11/22/2024
  Nasdaq
  Common
  12/28/2020
  Gift
  James and Christine Scott
  Y
  12/06/1971
  6067
  N/A
  Y
  11/22/2024
  /s/ J.P. Morgan Securities LLC as agent and attorney-in-fact for James R, Scott Jr.