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        <stateCountry>MA</stateCountry>
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      <titleOfIssuer>State Street U.S. Government Money Market Portfolio</titleOfIssuer>
      <otherUniqueId>FSSgAK161</otherUniqueId>
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    <signature>
      <registrant>STATE STREET INSTITUTIONAL INVESTMENT TRUST</registrant>
      <signatureDate>2020-02-07</signatureDate>
      <signature>/s/ Chad Hallett</signature>
      <nameOfSigningOfficer>Chad Hallett</nameOfSigningOfficer>
      <titleOfSigningOfficer>Deputy Treasurer</titleOfSigningOfficer>
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