<SEC-DOCUMENT>0001641172-25-026792.txt : 20250905
<SEC-HEADER>0001641172-25-026792.hdr.sgml : 20250905
<ACCEPTANCE-DATETIME>20250905213913
ACCESSION NUMBER:		0001641172-25-026792
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20250805
FILED AS OF DATE:		20250905
DATE AS OF CHANGE:		20250905

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Scott Jeremy
		CENTRAL INDEX KEY:			0001803925
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-34653
		FILM NUMBER:		251298384

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

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			NBAR5 Limited Partnership
		CENTRAL INDEX KEY:			0002076804
		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:		251298382

	BUSINESS ADDRESS:	
		STREET 1:		401 NORTH 31ST STREET
		STREET 2:		SUITE 700
		CITY:			BILLINGS
		STATE:			MT
		ZIP:			59101
		BUSINESS PHONE:		406-831-6855

	MAIL ADDRESS:	
		STREET 1:		401 NORTH 31ST STREET
		STREET 2:		SUITE 700
		CITY:			BILLINGS
		STATE:			MT
		ZIP:			59101

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Jeremy Scott TTEE, Jeremy Scott Revocable Trust Dtd 6/25/15
		CENTRAL INDEX KEY:			0001909124
		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:		251298383

	BUSINESS ADDRESS:	
		STREET 1:		859 MAIN STREET
		STREET 2:		BOX 592
		CITY:			DAYTON
		STATE:			WY
		ZIP:			82836
		BUSINESS PHONE:		(307) 461-7324

	MAIL ADDRESS:	
		STREET 1:		859 MAIN STREET
		STREET 2:		BOX 592
		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
		EIN:				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>ownership.xml
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2025-08-05</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001803925</rptOwnerCik>
            <rptOwnerName>Scott Jeremy</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>P.O. BOX 30918</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BILLINGS</rptOwnerCity>
            <rptOwnerState>MT</rptOwnerState>
            <rptOwnerZipCode>59116-0918</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001909124</rptOwnerCik>
            <rptOwnerName>Jeremy Scott TTEE, Jeremy Scott Revocable Trust Dtd 6/25/15</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>P.O. BOX 7113</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BILLINGS</rptOwnerCity>
            <rptOwnerState>MT</rptOwnerState>
            <rptOwnerZipCode>59116-0918</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0002076804</rptOwnerCik>
            <rptOwnerName>NBAR5 Limited Partnership</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>401 N. 31ST ST</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BILLINGS</rptOwnerCity>
            <rptOwnerState>MT</rptOwnerState>
            <rptOwnerZipCode>59116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2025-09-03</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>G</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>22928</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3512233</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>see footnote</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2025-08-05</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>L</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>216</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3512449</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>see footnote</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2946</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Composed of 3,416,108 shares held of record by NBar5 Limited Partnership, 93,511 shares held of record following both transactions reported herein by Jeremy Scott TTEE, Jeremy Scott Revocable Trust Dtd 6/25/15, and 2,830 shares held of record by Jeremy Scott's spouse.</footnote>
        <footnote id="F2">As a result of agreements entered into among the reporting persons, the issuer, and other stockholders of the issuer signatory thereto, the reporting persons may be deemed members of a group with the other signatories to the agreement 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 his or its pecuniary interest therein. The reporting persons expect to file future Forms 4 or 5, if any, together with the indication of direct or indirect ownership in Tables I and II being made from Jeremy Scott's perspective, unless expressly noted otherwise by footnote. The nature of beneficial ownership is described in detail by footnote for all reporting persons.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Kirk D. Jensen, as attorney in fact for reporting person</signatureName>
        <signatureDate>2025-09-05</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>NBAR5 Limited Partnership by: +</signatureName>
        <signatureDate>2025-09-05</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Jeremy Scott TTEE, Jeremy Scott Revocable Trust, Dtd 6/25/15, by: +</signatureName>
        <signatureDate>2025-09-05</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>+/s/ Timothy Leuthold, Attomey-in-Fact for Reporting Person</signatureName>
        <signatureDate>2025-09-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
