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    <filerInfo>
      <filer>
        <filerCredentials>
          <cik>0001520037</cik>
          <ccc>XXXXXXXX</ccc>
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      </filer>
      <liveTestFlag>LIVE</liveTestFlag>



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    <issuerInfo>
      <issuerCik>0001018963</issuerCik>
      <issuerName>ATI INC</issuerName>
      <secFileNumber>001-12001</secFileNumber>
      <issuerAddress>
        <com:street1>2021 MCKINNEY AVENUE</com:street1>
        <com:city>DALLAS</com:city>
        <com:stateOrCountry>TX</com:stateOrCountry>
        <com:zipCode>75201</com:zipCode>
      </issuerAddress>
      <issuerContactPhone>4123942800</issuerContactPhone>
      <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>Davis Elliot S</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>7039</noOfUnitsSold>
      <aggregateMarketValue>299157.50</aggregateMarketValue>
      <noOfUnitsOutstanding>128547760</noOfUnitsOutstanding>
      <approxSaleDate>06/29/2023</approxSaleDate>
      <securitiesExchangeName>NYSE</securitiesExchangeName>
    </securitiesInformation>
    <securitiesToBeSold>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <acquiredDate>01/04/2023</acquiredDate>
      <natureOfAcquisitionTransaction>Restricted Stock Vesting</natureOfAcquisitionTransaction>
      <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
      <isGiftTransaction>N</isGiftTransaction>
      <amountOfSecuritiesAcquired>3961</amountOfSecuritiesAcquired>
      <paymentDate>01/04/2023</paymentDate>
      <natureOfPayment>Compensation</natureOfPayment>
    </securitiesToBeSold>
    <securitiesToBeSold>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <acquiredDate>02/23/2023</acquiredDate>
      <natureOfAcquisitionTransaction>Performance Shares</natureOfAcquisitionTransaction>
      <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
      <isGiftTransaction>N</isGiftTransaction>
      <amountOfSecuritiesAcquired>2109</amountOfSecuritiesAcquired>
      <paymentDate>02/23/2023</paymentDate>
      <natureOfPayment>Compensation</natureOfPayment>
    </securitiesToBeSold>
    <securitiesToBeSold>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <acquiredDate>02/24/2023</acquiredDate>
      <natureOfAcquisitionTransaction>Restricted Stock Vesting</natureOfAcquisitionTransaction>
      <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
      <isGiftTransaction>N</isGiftTransaction>
      <amountOfSecuritiesAcquired>969</amountOfSecuritiesAcquired>
      <paymentDate>02/24/2023</paymentDate>
      <natureOfPayment>Compensation</natureOfPayment>
    </securitiesToBeSold>
    <nothingToReportFlagOnSecuritiesSoldInPast3Months>N</nothingToReportFlagOnSecuritiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>Elliot Davis</name>
        <address>
          <com:street1>2021 McKinney Avenue</com:street1>
          <com:city>Dallas</com:city>
          <com:stateOrCountry>TX</com:stateOrCountry>
          <com:zipCode>75201</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <saleDate>06/12/2023</saleDate>
      <amountOfSecuritiesSold>7039</amountOfSecuritiesSold>
      <grossProceeds>281560.00</grossProceeds>
    </securitiesSoldInPast3Months>
    <noticeSignature>
      <noticeDate>06/29/2023</noticeDate>
      <planAdoptionDates>
        <planAdoptionDate>02/09/2023</planAdoptionDate>
      </planAdoptionDates>
      <signature>/s/ Gerardo Ibarra-Munoz, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Elliot S. Davis</signature>
    </noticeSignature>
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144
0001520037
XXXXXXXX
LIVE
0001018963
ATI INC
001-12001
2021 MCKINNEY AVENUE
DALLAS
TX
75201
4123942800
Davis Elliot S
Officer
Common
Fidelity Brokerage Services LLC
900 Salem Street
Smithfield
RI
02917
7039
299157.50
128547760
06/29/2023
NYSE
Common
01/04/2023
Restricted Stock Vesting
Issuer
N
3961
01/04/2023
Compensation
Common
02/23/2023
Performance Shares
Issuer
N
2109
02/23/2023
Compensation
Common
02/24/2023
Restricted Stock Vesting
Issuer
N
969
02/24/2023
Compensation
N
Elliot Davis
2021 McKinney Avenue
Dallas
TX
75201
Common
06/12/2023
7039
281560.00
06/29/2023
02/09/2023
/s/ Gerardo Ibarra-Munoz, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Elliot S. Davis