<SEC-DOCUMENT>0000860413-18-000156-index.html : 20181011
<SEC-HEADER>0000860413-18-000156.hdr.sgml : 20181011
<ACCEPTANCE-DATETIME>20181011162844
ACCESSION NUMBER:		0000860413-18-000156
CONFORMED SUBMISSION TYPE:	425
PUBLIC DOCUMENT COUNT:		18
FILED AS OF DATE:		20181011
DATE AS OF CHANGE:		20181011

SUBJECT COMPANY:	

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

	FILING VALUES:
		FORM TYPE:		425
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-34653
		FILM NUMBER:		181118576

	BUSINESS ADDRESS:	
		STREET 1:		P O BOX 30918
		STREET 2:		401 NO 31ST STREET
		CITY:			BILLINGS
		STATE:			MT
		ZIP:			59116-0918
		BUSINESS PHONE:		4062555300

	MAIL ADDRESS:	
		STREET 1:		P O BOX 30918
		STREET 2:		401 NO 31ST STREET
		CITY:			BILLINGS
		STATE:			MT
		ZIP:			59116-0918

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	FIRST INTERSTATE BANCSYSTEM OF MONTANA INC
		DATE OF NAME CHANGE:	19930615

FILED BY:		

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

	FILING VALUES:
		FORM TYPE:		425

	BUSINESS ADDRESS:	
		STREET 1:		P O BOX 30918
		STREET 2:		401 NO 31ST STREET
		CITY:			BILLINGS
		STATE:			MT
		ZIP:			59116-0918
		BUSINESS PHONE:		4062555300

	MAIL ADDRESS:	
		STREET 1:		P O BOX 30918
		STREET 2:		401 NO 31ST STREET
		CITY:			BILLINGS
		STATE:			MT
		ZIP:			59116-0918

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	FIRST INTERSTATE BANCSYSTEM OF MONTANA INC
		DATE OF NAME CHANGE:	19930615
</SEC-HEADER>
<DOCUMENT>
<TYPE>425
<SEQUENCE>1
<FILENAME>fibk20181011-8k.htm
<DESCRIPTION>8-K
<TEXT>
Document 1 - file: fibk20181011-8k.htm

</DOCUMENT>
<DOCUMENT>
<TYPE>EX-2.1
<SEQUENCE>2
<FILENAME>ex-21iibkmergeragmt.htm
<DESCRIPTION>EX-2.1
<TEXT>
Document 2 - file: ex-21iibkmergeragmt.htm

</DOCUMENT>
<DOCUMENT>
<TYPE>EX-99.1
<SEQUENCE>3
<FILENAME>ex991ip.htm
<DESCRIPTION>EX-99.1
<TEXT>
Document 3 - file: ex991ip.htm

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<FILENAME>ex-992xiibkjointpr.htm
<DESCRIPTION>EX-99.2
<TEXT>
Document 4 - file: ex-992xiibkjointpr.htm

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<SEQUENCE>5
<FILENAME>ex991ip001.jpg
<DESCRIPTION>GRAPHIC
<TEXT>
Document 5 - file: ex991ip001.jpg

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<SEQUENCE>6
<FILENAME>ex991ip002.jpg
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<TEXT>
Document 6 - file: ex991ip002.jpg

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<SEQUENCE>7
<FILENAME>ex991ip003.jpg
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<TEXT>
Document 7 - file: ex991ip003.jpg

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<SEQUENCE>8
<FILENAME>ex991ip004.jpg
<DESCRIPTION>GRAPHIC
<TEXT>
Document 8 - file: ex991ip004.jpg

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<SEQUENCE>9
<FILENAME>ex991ip005.jpg
<DESCRIPTION>GRAPHIC
<TEXT>
Document 9 - file: ex991ip005.jpg

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<SEQUENCE>10
<FILENAME>ex991ip006.jpg
<DESCRIPTION>GRAPHIC
<TEXT>
Document 10 - file: ex991ip006.jpg

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<SEQUENCE>11
<FILENAME>ex991ip007.jpg
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<TEXT>
Document 11 - file: ex991ip007.jpg

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<FILENAME>ex991ip008.jpg
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Document 12 - file: ex991ip008.jpg

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<FILENAME>ex991ip009.jpg
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Document 13 - file: ex991ip009.jpg

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<TYPE>GRAPHIC
<SEQUENCE>14
<FILENAME>ex991ip010.jpg
<DESCRIPTION>GRAPHIC
<TEXT>
Document 14 - file: ex991ip010.jpg

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<DOCUMENT>
<TYPE>GRAPHIC
<SEQUENCE>15
<FILENAME>ex991ip011.jpg
<DESCRIPTION>GRAPHIC
<TEXT>
Document 15 - file: ex991ip011.jpg

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<TYPE>GRAPHIC
<SEQUENCE>16
<FILENAME>ex991ip012.jpg
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Document 16 - file: ex991ip012.jpg

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<TYPE>GRAPHIC
<SEQUENCE>17
<FILENAME>ex991ip013.jpg
<DESCRIPTION>GRAPHIC
<TEXT>
Document 17 - file: ex991ip013.jpg

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<TYPE>GRAPHIC
<SEQUENCE>18
<FILENAME>ex991ip014.jpg
<DESCRIPTION>GRAPHIC
<TEXT>
Document 18 - file: ex991ip014.jpg

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