<SEC-DOCUMENT>0000860413-24-000100.txt : 20240604
<SEC-HEADER>0000860413-24-000100.hdr.sgml : 20240604
<ACCEPTANCE-DATETIME>20240604180556
ACCESSION NUMBER:		0000860413-24-000100
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20240601
FILED AS OF DATE:		20240604
DATE AS OF CHANGE:		20240604

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Riki Rae Scott Davidson & John Heyneman Jr., Trustees FBO Riki Scott Davidson Exemption Trust Under the Scott Family 1996 Trust
		CENTRAL INDEX KEY:			0001908784
		ORGANIZATION NAME:           	
		STATE OF INCORPORATION:			WY
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-34653
		FILM NUMBER:		241019870

	BUSINESS ADDRESS:	
		STREET 1:		PO BOX 7113
		CITY:			BILLINGS
		STATE:			MT
		ZIP:			59103
		BUSINESS PHONE:		406-831-6855

	MAIL ADDRESS:	
		STREET 1:		PO BOX 7113
		CITY:			BILLINGS
		STATE:			MT
		ZIP:			59103

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			HEYNEMAN JOHN M JR
		CENTRAL INDEX KEY:			0001198518
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-34653
		FILM NUMBER:		241019874

	MAIL ADDRESS:	
		STREET 1:		C/O FIRST INTERSTATE BANCSYSTEM INC
		STREET 2:		P O BOX 30918
		CITY:			BILLINGS
		STATE:			MT
		ZIP:			59116

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Rae Ann Morss & John Heyneman Jr., Trustees FBO Rae Ann Morss Exemption Trust Under the Scott Family 1996 Trust
		CENTRAL INDEX KEY:			0001908849
		ORGANIZATION NAME:           	
		STATE OF INCORPORATION:			WY
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-34653
		FILM NUMBER:		241019872

	BUSINESS ADDRESS:	
		STREET 1:		PO BOX 7113
		CITY:			BILLINGS
		STATE:			MT
		ZIP:			59103
		BUSINESS PHONE:		406-831-6855

	MAIL ADDRESS:	
		STREET 1:		PO BOX 7113
		CITY:			BILLINGS
		STATE:			MT
		ZIP:			59103

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Towanda Investments Limited Partnership
		CENTRAL INDEX KEY:			0001908810
		ORGANIZATION NAME:           	
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-34653
		FILM NUMBER:		241019871

	BUSINESS ADDRESS:	
		STREET 1:		4100 BIG HORN AVE
		CITY:			SHERIDAN
		STATE:			WY
		ZIP:			82801
		BUSINESS PHONE:		307-763-2541

	MAIL ADDRESS:	
		STREET 1:		4100 BIG HORN AVE
		CITY:			SHERIDAN
		STATE:			WY
		ZIP:			82801

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			John M Heyneman Jr. Trust
		CENTRAL INDEX KEY:			0001908848
		ORGANIZATION NAME:           	
		STATE OF INCORPORATION:			WY
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-34653
		FILM NUMBER:		241019873

	BUSINESS ADDRESS:	
		STREET 1:		4100 BIG HORN AVE
		CITY:			SHERIDAN
		STATE:			WY
		ZIP:			82801
		BUSINESS PHONE:		307-763-2541

	MAIL ADDRESS:	
		STREET 1:		4100 BIG HORN AVE
		CITY:			SHERIDAN
		STATE:			WY
		ZIP:			82801

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			FIRST INTERSTATE BANCSYSTEM INC
		CENTRAL INDEX KEY:			0000860413
		STANDARD INDUSTRIAL CLASSIFICATION:	STATE COMMERCIAL BANKS [6022]
		ORGANIZATION NAME:           	02 Finance
		IRS NUMBER:				810331430
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		401 NO 31ST STREET
		CITY:			BILLINGS
		STATE:			MT
		ZIP:			59101
		BUSINESS PHONE:		4062555311

	MAIL ADDRESS:	
		STREET 1:		401 NO 31ST STREET
		CITY:			BILLINGS
		STATE:			MT
		ZIP:			59101

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	FIRST INTERSTATE BANCSYSTEM OF MONTANA INC
		DATE OF NAME CHANGE:	19930615
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wk-form4_1717538747.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2024-06-01</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000860413</issuerCik>
        <issuerName>FIRST INTERSTATE BANCSYSTEM INC</issuerName>
        <issuerTradingSymbol>FIBK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001198518</rptOwnerCik>
            <rptOwnerName>HEYNEMAN JOHN M JR</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>P.O. BOX 7113</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BILLINGS</rptOwnerCity>
            <rptOwnerState>MT</rptOwnerState>
            <rptOwnerZipCode>59103</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001908848</rptOwnerCik>
            <rptOwnerName>John M Heyneman Jr. Trust</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>P.O. BOX 7113</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BILLINGS</rptOwnerCity>
            <rptOwnerState>MT</rptOwnerState>
            <rptOwnerZipCode>59103</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001908849</rptOwnerCik>
            <rptOwnerName>Rae Ann Morss &amp; John Heyneman Jr., Trustees FBO Rae Ann Morss Exemption Trust Under the Scott Family 1996 Trust</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>P.O. BOX 7113</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BILLINGS</rptOwnerCity>
            <rptOwnerState>MT</rptOwnerState>
            <rptOwnerZipCode>59103</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001908810</rptOwnerCik>
            <rptOwnerName>Towanda Investments Limited Partnership</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>P.O. BOX 7113</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BILLINGS</rptOwnerCity>
            <rptOwnerState>MT</rptOwnerState>
            <rptOwnerZipCode>59103</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001908784</rptOwnerCik>
            <rptOwnerName>Riki Rae Scott Davidson &amp; John Heyneman Jr., Trustees FBO Riki Scott Davidson Exemption Trust Under the Scott Family 1996 Trust</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>P.O. BOX 7113</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BILLINGS</rptOwnerCity>
            <rptOwnerState>MT</rptOwnerState>
            <rptOwnerZipCode>59103</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2024-06-01</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>3014</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>17466</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1413401</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>see footnote</value>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Shares issuable upon vesting of restricted stock units granted to the reporting person pursuant to the Registrant's 2023 Equity and Incentive Plan. The restricted stock units vest on June 1, 2025, subject to the reporting persons provision of continuous service to the Registrant through the vesting date.</footnote>
        <footnote id="F2">Includes 10,079 shares previously reported as Direct shares are now held in Trust.</footnote>
        <footnote id="F3">Includes 890 shares held of record by John Heyneman's son.</footnote>
        <footnote id="F4">As a result of certain agreements entered into by and among the reporting persons, the Issuer, and certain other stockholders of the Issuer, the reporting persons may be deemed members of a group with the other signatories thereto and may be deemed to share beneficial ownership of the securities reported herein. Each of the reporting persons disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. The reporting persons expect to file future Forms 4 and 5, if any, together with John Heyneman, Jr. with the indication of direct or indirect ownership in Table I being made from John Heyneman, Jr.'s perspective. The nature of beneficial ownership is described in detail by footnote for all reporting persons.</footnote>
        <footnote id="F5">Composed of 150,000 shares held of record by John M Heyneman Jr. Trust, 85,836 shares held of record by Riki Rae Scott Davidson &amp; John Heyneman Jr., Trustees FBO Riki Scott Davidson Exemption Trust Under the Scott Family 1996 Trust, 85,836 shares held of record by Rae Ann Morss &amp; John Heyneman Jr., Trustees FBO Rae Ann Morss Exemption Trust Under the Scott Family 1996 Trust, 1,085,792 shares held of record by Towanda Investments Limited Partnership, 3,977 shares held of record by John Heyneman, Jr.'s spouse, 1070 shares held of record by John Heyneman, Jr.'s daughter, and 890 shares held of record by John Heyneman's son.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>JOHN M. HEYNEMAN, JR., By:**</signatureName>
        <signatureDate>2024-06-04</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Kirk D. Jensen, Attorney-in-Fact for Reporting Person</signatureName>
        <signatureDate>2024-06-04</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>J.S. Investments Limited Partnership, by: +</signatureName>
        <signatureDate>2024-06-04</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>John M. Heyneman, Jr. Trust By+</signatureName>
        <signatureDate>2024-06-04</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Riki Rae Scott Davidson and John Heyneman Jr., Trustees FBO Riki Scott Davidson Exemption Trust Under the Scott Family 1996 Trust By+</signatureName>
        <signatureDate>2024-06-04</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Rae Ann Morss and John Heyneman Jr., Trustees FBO Rae Ann Morss Exemption Trust Under the Scott Family 1996 Trust By+</signatureName>
        <signatureDate>2024-06-04</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Towanda Investments Limited Partnership By+</signatureName>
        <signatureDate>2024-06-04</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>+/s/ Timothy Leuthold, Attorney-in-Fact for Reporting Person</signatureName>
        <signatureDate>2024-06-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
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</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
