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UNITED STATES SECURITIES AND EXCHANGE COMMISSION

Washington D.C. 20549

FORM 10-K

(Mark One)

☑    Annual Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

For the fiscal year ended December 31, 2020

or

☐    Transition Report Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

For the transition period from                      to                     .

Commission File Number: 001-34653

Securities registered pursuant to Section 12(b) of the Act:

Title of each class			Trading Symbol(s)			Name of exchange on which registered
Class A common stock, no par value			FIBK			NASDAQ

			Securities registered pursuant to Section 12(g) of the Act:
			Class B common stock
			(Title of class)

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. þ Yes o No

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. o Yes þ No

Indicate by check mark whether the registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. þ Yes o No

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§223.405 of this chapter) during the preceding 12 months (or for such shorter period that registrant was required to submit such files). þ Yes o No

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growth company” in Rule 12b-2 of the Exchange Act. (Check one):

Large accelerated filer

☒

Accelerated filer

☐

Non-accelerated filer

☐

Smaller reporting company

☐

Emerging growth company

☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. o

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report. ☑

Indicate by check mark if the registrant is a shell company (as defined in Rule 12b-2 of the Act.) ☐ Yes þ No

The aggregate market value of voting and non-voting common equity held by non-affiliates, computed by reference to the price at which the common equity was last sold on the NASDAQ, as of the last business day of the registrant’s most recently completed second fiscal quarter was $1,379,587,569.

Indicate the number of shares outstanding of each of the registrant’s classes of common stock as of January 31, 2021:

The registrant intends to file a definitive Proxy Statement for the Annual Meeting of Shareholders scheduled to be held May 26, 2021. The information required by Part III of this Form 10-K is incorporated by reference to such Proxy Statement.

			FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES
			Index
			December 31, 2020
						Page Nos.
			PART I
Item 1			Business			3
Item 1A			Risk Factors			14
Item 1B			Unresolved Staff Comments			30
Item 2			Properties			30
Item 3			Legal Proceedings			30
Item 4			Mine Safety Disclosure			30
			PART II
Item 5			Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities			30
Item 6			Selected Consolidated Financial Data			32
Item 7			Management’s Discussion and Analysis of Financial Condition and Results of Operations			33
Item 7A			Quantitative and Qualitative Disclosures About Market Risk			61
Item 8			Financial Statements and Supplementary Data			63
Item 9			Changes in and Disagreements with Accountants on Accounting and Financial Disclosure			63
Item 9A			Controls and Procedures			64
Item 9B			Other Information			66
			PART III
Item 10			Directors, Executive Officers and Corporate Governance.			66
Item 11			Executive Compensation			66
Item 12			Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters			66
Item 13			Certain Relationships and Related Transactions and Director Independence			66
Item 14			Principal Accountant Fees and Services			66
			PART IV
Item 15			Exhibits and Financial Statement Schedules			66
			Report of Independent Registered Public Accounting Firm			67
			Consolidated Balance Sheets			69
			Consolidated Statements of Income			70
			Consolidated Statements of Comprehensive Income			71
			Consolidated Statements of Stockholders' Equity			72
			Consolidated Statements of Cash Flows			73
			Notes to Consolidated Financial Statements			75
			Exhibits			133
Item 16			Form 10-K Summary			134