UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington D.C. 20549

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FORM 8-K

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CURRENT REPORT

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of report (date of earliest event reported): July 13 23, 2026

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FIRST INTERSTATE BANCSYSTEM, INC.

(Exact name of registrant as specified in its charter)

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Delaware

001-34653

81-0331430

(State or other jurisdiction of
incorporation or organization)

(Commission
File No.)

(IRS Employer
Identification No.)

401 North 31st Street

Billings,

59101

(Address of principal executive offices)

(zip code)


	(406)	255-5311
(Registrant’s telephone number, including area code)

	Not Applicable
(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a- 12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

* * * * *

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


Title of each class	Trading Symbol(s)	Name of exchange on which registered
Common stock, $0.00001 par value	FIBK	NASDAQ

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

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. ☐

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Item 52.02 ~~Departure~~Results of ~~Directors~~Operations orand ~~Certain~~Financial ~~Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers~~Condition.

On July 13 23, 2026, ~~the~~First ~~Board~~Interstate ofBancSystem, ~~Directors~~Inc. (the “~~Board~~Company”) ofissued ~~First~~a ~~Interstate~~press ~~BancSystem~~release regarding its financial results for the quarter ended June 30, ~~Inc~~2026. (A copy of the ~~“Company”)~~press ~~appointed~~release ~~Mr.~~is ~~Matthew~~furnished ~~Ritter~~herewith as Exhibit 99.1 and Mris incorporated by reference herein. ~~Kevin~~Neither ~~Turner~~the toinformation ~~serve~~included asor ~~Class~~incorporated IIby ~~directors~~reference onunder ~~the~~this ~~Board~~Item 2.02, ~~each~~nor ~~with~~the apress ~~term~~release ~~expiring~~furnished atherewith, ~~the~~shall ~~Company’s~~be ~~2029~~deemed ~~annual~~to ~~meeting~~be of“filed” ~~shareholders.~~for ~~Messrs.~~purposes ~~Ritter~~of ~~and~~Section 18 ~~Turner~~of ~~will~~the ~~fill~~Securities ~~vacancies~~Exchange onAct of 1934 (the ~~Board~~“Exchange ~~created~~Act”) or incorporated by ~~the~~reference ~~Board’s~~into ~~decision~~any toregistration ~~increase~~statement or other document filed pursuant to the ~~size~~Securities Act of 1933 (the ~~Board~~“Securities Act”) or the Exchange Act, except as expressly set forth by specific reference in such filing.

MrItem 7.01 ~~Ritter~~Regulation ~~has~~FD ~~more than 25 years of finance, real estate, energy and private investment experience~~Disclosure. Mr. Ritter is Co-Founder and Principal of KnightBridge Capital, LLC, a private investment firm, and is Principal and Co-Founder of Pinnacle Real Estate Advisors, LLC. Mr. Ritter previously served as Co-Founder of Clear Creek Advisors from 2017 to 2024, as Managing Member of Wolf Resources, LLC from 2016 to 2020 and as a Partner of Arrowhead Energy Partners LLC from 2020 to 2021. From December 2022 to January 2026, Mr. Ritter served as a director of FirstBank Holding Company of Colorado, Inc.

~~Mr.~~On ~~Turner~~July 23, ~~served~~2026, asthe ~~Chief~~Company ~~Operating~~posted ~~Officer~~a ofnew ~~Microsoft~~corporate ~~Corporation~~presentation ~~from~~(the ~~2005~~“Presentation”) toon ~~2016~~the ~~and,~~Events ~~prior~~& toPresentations ~~that,~~page ~~held~~of ~~various~~the ~~leadership~~Company’s ~~roles~~website at ~~Walmart Inc~~https://www.fibk.com. ~~from~~The ~~1985 to 2005~~Presentation, ~~including~~which asis ~~President~~furnished ~~and~~with ~~Chief~~this ~~Executive~~Current ~~Officer~~Report ofas ~~Sam’s~~Exhibit ~~Club~~99.2 and ~~Executive~~incorporated ~~Vice~~herein ~~President~~by ~~and~~reference, ~~Chief~~updates ~~Information~~previously ~~Officer.~~furnished ~~Mr.~~presentations ~~Turner also served as President~~ and ~~Chief~~provides ~~Executive~~an ~~Officer~~overview of ~~Core~~the ~~Scientific,~~Company ~~Inc.~~and ~~from~~its ~~2018~~operations. toNeither ~~2021~~the ~~and~~information asincluded ~~Vice~~or ~~Chairman~~incorporated ~~and~~by ~~Senior~~reference ~~Advisor~~under tothis ~~the~~Item ~~Chief~~7.01, ~~Executive~~nor ~~Officer~~the ofPresentation ~~Albertsons~~furnished ~~Companies~~herewith, ~~Inc.~~shall ~~from~~be ~~August~~deemed ~~2017~~ to ~~February~~be ~~2020.~~“filed” ~~Mr.~~for ~~Turner~~purposes ~~currently~~of ~~serves~~Section as18 ~~a director~~ of ~~Albertsons~~the ~~Companies,~~Exchange ~~Inc.,~~Act ~~Non-Executive~~or ~~Chair~~incorporated ofby ~~Zayo~~reference ~~Group~~into ~~Holdings,~~any ~~Inc.~~filing ~~and~~under athe Securities ~~director~~Act ofor ~~EdgeConnex~~the Exchange Act, ~~and~~except ~~previously~~as ~~served~~expressly onset ~~the~~forth ~~boards~~by ofspecific ~~Nordstrom,~~reference ~~Inc.,~~in ~~and~~such ~~Core~~a ~~Scientific, Inc~~filing.

~~There was no arrangement or understanding pursuant to which either Mr~~Item 8.01 Ritter or Mr. Turner was appointed as a director. Since the beginning of the Company’s last fiscal year, an entity through which Mr. Ritter conducts his investment business incurred indebtedness in the form of a loan as a client of First Interstate Bank, the Company’s wholly owned bank subsidiary. The loan was made in the ordinary course of business, on substantially the same terms, including interest rates and collateral, as those prevailing at the time for comparable loans with persons not related to the Company, and did not involve more than a normal risk of collectability or present other unfavorable features. Other ~~than the foregoing, neither Mr~~Events. Ritter nor Mr. Turner has engaged in any transaction with the Company since the beginning of the Company’s last fiscal year that would be reportable as a related person transaction under Item 404(a) of Regulation S-K.

~~The~~On ~~Board~~July 23, ~~has~~2026, ~~determined~~the ~~that~~Company ~~each~~also ofannounced ~~Mr.~~that ~~Ritter and Mr. Turner will be “independent” as defined under applicable NASDAQ Marketplace Rules at~~ the ~~time~~Board of ~~their~~Directors ~~appointments. Each~~ of ~~Messrs. Ritter and Turner will be entitled to receive~~ the ~~same compensation for service as a director as is provided to other non-employee directors of the~~ Company ~~pursuant to the Company’s non-employee director compensation program~~declared, ~~which~~on ~~includes the issuance of restricted stock units~~July 22, ~~as described under the heading “Director Compensation” in the Company’s proxy statement for its~~ 2026, ~~annual~~a ~~meeting~~dividend of ~~shareholders~~$0.47 ~~filed~~per ~~with~~share, ~~the~~that ~~Securities~~is ~~and~~payable ~~Exchange Commission on April 16~~August 14, 2026. ~~Mr. Ritter has been appointed~~ to ~~serve~~shareholders onof ~~the~~record ~~Board’s~~of ~~Risk Committee and Technology, Innovation and Operations Committee, and Mr. Turner has been appointed to serve on~~ the ~~Board’s~~Company ~~Audit~~as ~~Committee~~of ~~and Technology~~August 4, ~~Innovation and Operations Committee~~2026.

Following Messrs. Ritter’s and Turner’s appointments, as of July 16, 2026, there are currently 13 members on the Board, four of whom are designated as Class I directors, five of whom are designated as Class II directors, and four of whom are designated as Class III directors.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits.


(d)	Exhibit Number	Description

	99.1	Press Release dated July 23, 2026.

	99.2	Presentation

	104	Cover Page Interactive Data File (embedded within Inline XBRL document).

			Exhibit No.						Exhibit Description
			104						Cover Page Interactive Data File (embedded within Inline XBRL document).

SIGNATURES

Pursuant to the requirements of the Securities and Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Date: July 16 23, 2026



			FIRST INTERSTATE BANCSYSTEM, INC.

			By:			/s/ JAMES A. REUTER
						James A. Reuter
						President and Chief Executive Officer

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