<SEC-DOCUMENT>0000860413-24-000104.txt : 20240613
<SEC-HEADER>0000860413-24-000104.hdr.sgml : 20240613
<ACCEPTANCE-DATETIME>20240613184640
ACCESSION NUMBER:		0000860413-24-000104
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20240611
FILED AS OF DATE:		20240613
DATE AS OF CHANGE:		20240613

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Harper Grace Scott Trust
		CENTRAL INDEX KEY:			0001908895
		ORGANIZATION NAME:           	
		STATE OF INCORPORATION:			MT
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-34653
		FILM NUMBER:		241042581

	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:			Scott Jonathan R
		CENTRAL INDEX KEY:			0001361935
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-34653
		FILM NUMBER:		241042584

	MAIL ADDRESS:	
		STREET 1:		P.O. BOX 30918
		CITY:			BILLINGS
		STATE:			MT
		ZIP:			59116

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Harrison William Scott Trust
		CENTRAL INDEX KEY:			0001908873
		ORGANIZATION NAME:           	
		STATE OF INCORPORATION:			MT
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-34653
		FILM NUMBER:		241042580

	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:			IXL Ltd Liability Co
		CENTRAL INDEX KEY:			0001909090
		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:		241042583

	BUSINESS ADDRESS:	
		STREET 1:		BOX 190
		CITY:			DAYTON
		STATE:			WY
		ZIP:			82836
		BUSINESS PHONE:		307-752-5605

	MAIL ADDRESS:	
		STREET 1:		BOX 190
		CITY:			DAYTON
		STATE:			WY
		ZIP:			82836

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Holland Elizabeth Scott Trust
		CENTRAL INDEX KEY:			0001908953
		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:		241042579

	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:			Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04
		CENTRAL INDEX KEY:			0001908962
		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:		241042582

	BUSINESS ADDRESS:	
		STREET 1:		BOX 190
		CITY:			DAYTON
		STATE:			WY
		ZIP:			82836
		BUSINESS PHONE:		307-752-5605

	MAIL ADDRESS:	
		STREET 1:		BOX 190
		CITY:			DAYTON
		STATE:			WY
		ZIP:			82836

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_1718318792.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2024-06-11</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001361935</rptOwnerCik>
            <rptOwnerName>Scott Jonathan R</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>PO 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>0001909090</rptOwnerCik>
            <rptOwnerName>IXL Ltd Liability Co</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>0001908962</rptOwnerCik>
            <rptOwnerName>Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04</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>0001908895</rptOwnerCik>
            <rptOwnerName>Harper Grace Scott 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>0001908873</rptOwnerCik>
            <rptOwnerName>Harrison William Scott 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>0001908953</rptOwnerCik>
            <rptOwnerName>Holland Elizabeth Scott 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>2024-06-11</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>29499</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>25.29</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1021663</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2024-06-12</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>14403</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>26.14</value>
                    <footnoteId id="F4"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1007260</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F3"/>
                    <footnoteId id="F5"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>14114</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The price reported in column 4 is a weighted-average price. These shares were sold in multiple transactions at prices ranging from $25.14 to $25.42. The reporting person undertakes to provide to First Interstate BancSystem, Inc., any security holders of First Interstate BancSystem, Inc., or the staff of the Securities and Exchange Commission, upon request, the full information regarding the number of shares sold at each separate price within the ranges set forth above.</footnote>
        <footnote id="F2">Composed of 615,872 shares held of record by Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04, 209,678 shares held of record by IXL Limited Liability Company, 48,704 shares held of record by Holland Elizabeth Scott Trust, 48,704 shares held of record by Harper Grace Scott Trust, 48,705 shares held of record by Harrison William Scott Trust and 50,000 shares held of record by Jonathan Scott's spouse.</footnote>
        <footnote id="F3">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 Jonathan R. Scott with the indication of direct or indirect ownership in Table I and Table II being made from Jonathan R. Scott's perspective. The nature of beneficial ownership is described in detail by footnote for all reporting persons.</footnote>
        <footnote id="F4">3. The price reported in column 4 is a weighted-average price. These shares were sold in multiple transactions at prices ranging from $25.75 to $26.49. The reporting person undertakes to provide to First Interstate BancSystem, Inc., any security holders of First Interstate BancSystem, Inc., or the staff of the Securities and Exchange Commission, upon request, the full information regarding the number of shares sold at each separate price within the ranges set forth above.</footnote>
        <footnote id="F5">Composed of 615,872 shares held of record by Jonathan Scott as Trustee of the Jonathan R Scott Trust Dated as of 4/21/04, 209,678 shares held of record by IXL Limited Liability Company, 43,903 shares held of record by Holland Elizabeth Scott Trust, 43,903 shares held of record by Harper Grace Scott Trust, 43,904 shares held of record by Harrison William Scott Trust and 50,000 shares held of record by Jonathan Scott's spouse.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>JONATHAN R. SCOTT, By:</signatureName>
        <signatureDate>2024-06-13</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Kirk D. Jensen, Attorney-in-Fact for Reporting Person</signatureName>
        <signatureDate>2024-06-13</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>IXL Limited Liability Company, By:+</signatureName>
        <signatureDate>2024-06-13</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>JONATHAN SCOTT AS TRUSTEE OF THE JONATHAN R SCOTT TRUST DATED AS OF 4/21/04, By: +</signatureName>
        <signatureDate>2024-06-13</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>HARPER GRACE SCOTT TRUST, By: +</signatureName>
        <signatureDate>2024-06-13</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>HOLLAND ELIZABETH SCOTT TRUST, By: +</signatureName>
        <signatureDate>2024-06-13</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>HARRISON WILLIAM SCOTT TRUST, By: +</signatureName>
        <signatureDate>2024-06-13</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>+/s/ Timothy Leuthold, Attorney-in-Fact for Reporting Person</signatureName>
        <signatureDate>2024-06-13</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
