First Interstate BancSystem, Inc. (NASDAQ:FIBK) (the "Company") today reported financial results for the first quarter of 2026. For the quarter, the Company reported net income of $60.2 million, or $0.61 per diluted share, which compares to net income of $108.8 million, or $1.08 per diluted share, for the fourth quarter of 2025 and net income of $50.2 million, or $0.49 per diluted share, for the first quarter of 2025.

HIGHLIGHTS

Net interest margin increased to 3.41% for the first quarter of 2026, a 5-basis point increase from the fourth quarter of 2025 and a 22-basis point increase from the first quarter of 2025.
Other borrowed funds were zero as of March 31, 2026 and December 31, 2025 as compared to $960.0 million as of March 31, 2025.
Net charge-offs decreased $19.7 million to $2.4 million, or an annualized 0.06% of average loans outstanding, as of March 31, 2026, from $22.1 million, or an annualized 0.56% of average loans outstanding, as of December 31, 2025, and decreased $6.6 million from $9.0 million, or an annualized 0.21% of average loans outstanding, as of March 31, 2025.
Criticized loans decreased $18.6 million to $1,033.2 million as of March 31, 2026, compared to $1,051.8 million as of December 31, 2025, and increased $7.1 million, compared to $1,026.1 million as of March 31, 2025.
Non-performing assets increased $24.2 million, or 17.5%, to $162.5 million as of March 31, 2026, from $138.3 million as of December 31, 2025 and decreased $35.9 million, or 18.1%, from $198.4 million as of March 31, 2025.
Total deposits decreased $205.3 million to $21,883.0 million as of March 31, 2026, compared to $22,088.3 million as of December 31, 2025 primarily due to decreases in all deposit categories except for savings deposits during the first quarter. Total deposits decreased $849.8 million, or 3.7% from March 31, 2025 with decreases in all deposit categories except for savings deposits primarily driven by the Arizona and Kansas branch sales which consisted of $641.6 million of deposits.
During the first quarter of 2026, the Company repurchased 2.39 million shares of common stock for a total repurchase of approximately $84.0 million, in addition to the Company's repurchase of approximately 3.65 million shares of common stock through December 31, 2025 for a total repurchase of approximately $117.6 million. On January 27, 2026, the board of directors authorized an increase to the repurchase program of an additional $150.0 million, or a total of $300.0 million authorized since its adoption in August of 2025.
Common equity tier 1 capital ratio decreased 8 basis points during the first quarter of 2026 to 14.30%, compared to the fourth quarter of 2025, primarily as a result of shares repurchased during first quarter, partially offset by lower risk-weighted assets primarily driven by lower loan balances.

"We are pleased to see continued improvement in our net interest margin and continue to execute on our previously announced share repurchase authorization," said James A Reuter, President and Chief Executive Officer of the Company. "We are encouraged with the underlying momentum in the business as we enter the second quarter, with a strong commercial pipeline and ongoing fixed asset repricing supporting our confidence in continued earnings improvement."

DIVIDEND DECLARATION

On April 28, 2026, the Company's board of directors declared a dividend of $0.47 per common share, payable on May 21, 2026, to common stockholders of record as of May 11, 2026. The dividend equates to a 5.3% annualized yield based on the $35.76 per share average closing price of the Company's common stock as reported on NASDAQ during the first quarter of 2026.

NET INTEREST INCOME

Net interest income decreased $5.7 million to $200.7 million during the first quarter of 2026, compared to net interest income of $206.4 million during the fourth quarter of 2025. Net interest income decreased $4.3 million, or 2.1%, during the first quarter of 2026 compared to the first quarter of 2025. The quarterly decline from the fourth quarter of 2025 was primarily driven by lower interest income due to reduced loan yields and balances, and fewer accrual days, partially offset by higher investment balances and yields and lower interest expense due to reduced deposit balances and rates. Year-over-year lower interest earning assets and interest bearing liabilities were partially influenced by the reduction in loans and deposits related to the sale of the Arizona and Kansas branches during the fourth quarter of 2025, which resulted in a reduction of net interest income, in the first quarter of 2026.

Interest accretion attributable to the fair value of acquired loans, related to prior acquisitions, contributed to net interest income during the first quarter of 2026, the fourth quarter of 2025, and the first quarter of 2025, in the amounts of $3.1 million, $2.6 million, and $4.7 million, respectively.

Net interest margin ratio was 3.41% for the first quarter of 2026, compared to 3.36% during the fourth quarter of 2025, and 3.19% during the first quarter of 2025. Net FTE (fully-taxable equivalent) interest margin ratio¹ was 3.43% for the first quarter of 2026, compared to 3.38% during the fourth quarter of 2025, and 3.22% during the first quarter of 2025. Excluding interest accretion from the fair value of acquired loans, the adjusted net FTE interest margin ratio¹, was 3.38%, an increase of 4 basis points from the prior quarter, primarily driven by higher yields on higher average investment security balances and lower rates on lower interest bearing deposits, partially offset by lower loan yields on lower average loan balances. Excluding interest accretion from the fair value of acquired loans, on a year-over-year basis, the adjusted net FTE interest margin ratio increased 24 basis points, primarily as a result of lower interest expense resulting from decreased other borrowed funds balances.

____________________
¹		Represents a Non-GAAP financial measure. See "Non-GAAP Financial Measures" and the corresponding table captioned "Non-GAAP Financial Measures" included below for an explanation of the manner in which this measure is calculated and a reconciliation to this measure's most directly comparable GAAP financial measure.

PROVISION FOR CREDIT LOSSES

During the first quarter of 2026, the Company recorded a provision for credit losses of $6.7 million. This compares to a provision for credit losses of $7.1 million and $20.0 million during the fourth quarter of 2025 and the first quarter of 2025, respectively.

For the first quarter of 2026, net loan charge-offs were $2.4 million, or an annualized 0.06% of average loans outstanding, compared to net loan charge-offs of $22.1 million, or an annualized 0.56% of average loans outstanding, for the fourth quarter of 2025 and net loan charge-offs of $9.0 million, or an annualized 0.21% of average loans outstanding, for the first quarter of 2025. Net loan charge-offs in the first quarter of 2026 were composed of charge-offs of $6.5 million offset by recoveries of $4.1 million. Net loan charge-offs in the fourth quarter of 2025 were composed of charge-offs of $24.5 million, primarily related to one loan of $15.8 million, which were offset by recoveries of $2.4 million. Net loan charge-offs in the first quarter of 2025 were composed of charge-offs of $10.8 million, which were offset by recoveries of $1.8 million.

The Company's allowance for credit losses as a percentage of period-end loans held for investment was 1.33% at March 31, 2026, compared to 1.26% at December 31, 2025 and 1.24% at March 31, 2025. Coverage of non-performing loans decreased to 125.6% at March 31, 2026, compared to 141.9% at December 31, 2025 and increased from 110.5% at March 31, 2025.

NONINTEREST INCOME

For the Quarter Ended	Mar 31, 2026		Dec 31, 2025		$ Change			% Change		Mar 31, 2025		$ Change			% Change
(Dollars in millions)	Mar 31, 2026		Dec 31, 2025		$ Change			% Change		Mar 31, 2025		$ Change			% Change
Payment services revenues	$	15.6	$	16.2	$	(0.6	)	(3.7	)%	$	17.1	$	(1.5	)	(8.8	)%
Mortgage banking revenues		1.3		1.1		0.2		18.2			1.4		(0.1	)	(7.1	)
Wealth management revenues		10.5		10.7		(0.2	)	(1.9	)		9.8		0.7		7.1
Service charges on deposit accounts		6.5		6.5		—		—			6.6		(0.1	)	(1.5	)
Other service charges, commissions, and fees		2.1		2.3		(0.2	)	(8.7	)		2.3		(0.2	)	(8.7	)
Other income		5.1		69.8		(64.7	)	(92.7	)		4.8		0.3		6.3
Total noninterest income	$	41.1	$	106.6	$	(65.5	)	(61.4	)%	$	42.0	$	(0.9	)	(2.1	)%

Noninterest income was $41.1 million for the first quarter of 2026, decreasing $65.5 million compared to the fourth quarter of 2025 and decreasing $0.9 million compared to the first quarter of 2025. The decrease from the fourth quarter of 2025 was primarily due to the $62.7 million gain recorded in other income from the sale of the Arizona and Kansas branches during the fourth quarter of 2025.

Payment services revenues decreased $0.6 million and $1.5 million during the first quarter of 2026 compared to the fourth quarter of 2025 and the first quarter of 2025, respectively. The year-over-year decrease was mainly the result of lower consumer credit card interchange during the first quarter of 2026 as compared to the first quarter of 2025, related to the outsourcing of consumer credit cards in the second quarter of 2025.

NONINTEREST EXPENSE

For the Quarter Ended	Mar 31, 2026			Dec 31, 2025		$ Change			% Change		Mar 31, 2025		$ Change			% Change
(Dollars in millions)	Mar 31, 2026			Dec 31, 2025		$ Change			% Change		Mar 31, 2025		$ Change			% Change
Salaries and wages	$	68.5		$	74.8	$	(6.3	)	(8.4	)%	$	68.6	$	(0.1	)	(0.1	)%
Employee benefits		21.2			18.5		2.7		14.6			20.0		1.2		6.0
Occupancy and equipment		18.6			19.6		(1.0	)	(5.1	)		18.7		(0.1	)	(0.5	)
Other intangible amortization		3.3			3.4		(0.1	)	(2.9	)		3.4		(0.1	)	(2.9	)
Other expenses		47.1			50.4		(3.3	)	(6.5	)		49.4		(2.3	)	(4.7	)
Other real estate owned expense, net		(1.1	)		—		(1.1	)	NM			0.5		(1.6	)	NM
Total noninterest expense	$	157.6		$	166.7	$	(9.1	)	(5.5	)%	$	160.6	$	(3.0	)	(1.9	)%

The Company's noninterest expense was $157.6 million for the first quarter of 2026, a decrease of $9.1 million from the fourth quarter of 2025 and a decrease of $3.0 million from the first quarter of 2025.

Salary and wages expense decreased $6.3 million to $68.5 million during the first quarter of 2026 compared to the fourth quarter of 2025, primarily due to lower short-term incentive accruals of $2.9 million and lower severance accruals of $2.9 million during the first quarter of 2026. Salaries and wages expense decreased $0.1 million to $68.5 million during the first quarter of 2026 compared to $68.6 million during the first quarter of 2025.

Employee benefit expenses increased $2.7 million to $21.2 million during the first quarter of 2026, compared to $18.5 million during the fourth quarter of 2025, primarily due to the seasonal reset of payroll taxes, partially offset by lower long-term incentives and medical insurance costs. Employee benefit expenses increased $1.2 million from $20.0 million during the first quarter of 2025, primarily due to higher health insurance costs of $3.1 million, partially offset by $1.6 million of lower long-term incentive accruals during the first quarter of 2026.

Occupancy and equipment expenses decreased $1.0 million to $18.6 million during the first quarter of 2026, compared to $19.6 million during the fourth quarter of 2025, primarily due to higher depreciation expense as a result of the impairments in the fourth quarter of 2025 for the pending branch closures that occurred in the first quarter of 2026. Occupancy and equipment expenses increased $0.1 million during the first quarter of 2026 from $18.7 million during the first quarter of 2025.

Other expenses decreased $3.3 million during the first quarter of 2026 compared to the fourth quarter of 2025, primarily due to a decrease of $1.5 million in professional fees and decreases in donations and various other expense categories. Other expenses decreased $2.3 million during the first quarter of 2026 compared to the first quarter of 2025, primarily due to a decrease in FDIC special assessment accruals.

Other real estate owned expense, net decreased $1.1 million during the first quarter of 2026 compared to the fourth quarter of 2025 and decreased $1.6 million during the first quarter of 2026 compared to the first quarter of 2025, primarily due to a positive fair value adjustment to a commercial property.

BALANCE SHEET

Total assets decreased $213.8 million, or 0.8%, to $26,426.8 million as of March 31, 2026, from $26,640.6 million as of December 31, 2025, primarily due to decreases in loans and cash and cash equivalents, which were partially offset by an increase in investment securities. Total assets decreased $1,853.0 million from $28,279.8 million as of March 31, 2025, primarily due to a decrease in loans which was partially driven by the sale of the branches in Arizona and Kansas during the fourth quarter of 2025. The funds from the loan declines were partially used to pay down debt, which were partially offset by increases in investment securities and cash and cash equivalents.

Investment securities increased $379.8 million to $8,010.0 million as of March 31, 2026, from $7,630.2 million as of December 31, 2025, primarily resulting from purchases of investment securities, partially offset by pay-downs, maturities, called securities, and a $23.5 million decrease in fair market values during the first quarter. Investment securities increased $506.2 million from $7,503.8 million as of March 31, 2025, primarily resulting from purchases of investment securities and a $93.6 million increase in fair market values during the period, partially offset by pay-downs, maturities, and called securities.

The following table presents the composition and comparison of loans held for investment as of the quarters-ended:

	Mar 31, 2026			Dec 31, 2025			$ Change			% Change		Mar 31, 2025			$ Change			% Change
Real Estate:
Commercial	$	8,040.5		$	8,144.4		$	(103.9	)	(1.3	)%	$	9,196.1		$	(1,155.6	)	(12.6	)%
Construction		669.1			837.2			(168.1	)	(20.1	)		1,097.3			(428.2	)	(39.0	)
Residential		2,084.3			2,108.8			(24.5	)	(1.2	)		2,161.4			(77.1	)	(3.6	)
Agricultural		619.2			629.0			(9.8	)	(1.6	)		678.1			(58.9	)	(8.7	)
Total real estate		11,413.1			11,719.4			(306.3	)	(2.6	)		13,132.9			(1,719.8	)	(13.1	)
Consumer:
Indirect		419.4			477.5			(58.1	)	(12.2	)		680.2			(260.8	)	(38.3	)
Direct and advance lines		128.0			131.5			(3.5	)	(2.7	)		132.4			(4.4	)	(3.3	)
Credit card		—			—			—		—			74.2			(74.2	)	(100.0	)
Total consumer		547.4			609.0			(61.6	)	(10.1	)		886.8			(339.4	)	(38.3	)
Commercial		2,342.9			2,359.6			(16.7	)	(0.7	)		2,770.6			(427.7	)	(15.4	)
Agricultural		426.8			520.2			(93.4	)	(18.0	)		595.8			(169.0	)	(28.4	)
Other, including overdrafts		5.8			1.7			4.1		241.2			1.8			4.0		222.2
Deferred loan fees and costs		(7.6	)		(8.3	)		0.7		(8.4	)		(10.6	)		3.0		(28.3	)
Loans held for investment, net of deferred loan fees and costs	$	14,728.4		$	15,201.6		$	(473.2	)	(3.1	)%	$	17,377.3		$	(2,648.9	)	(15.2	)%

The decline in loans was impacted by $58.1 million of continued amortization of the indirect portfolio for which the Company stopped originating loans during the first quarter of 2025, agricultural loan payoffs, and other loan paydowns and payoffs during the first quarter of 2026.

The ratio of loans held for investment to deposits was 67.3%, as of March 31, 2026, compared to 68.8% as of December 31, 2025 and 76.4% as of March 31, 2025.

Total deposits decreased $205.3 million to $21,883.0 million as of March 31, 2026, from $22,088.3 million as of December 31, 2025, primarily due to decreases in all deposit categories except for savings deposits during the first quarter. Total deposits decreased $849.8 million, or 3.7%, from $22,732.8 million as of March 31, 2025, with decreases in all deposit categories except for savings deposits during the first quarter of 2026, primarily driven by the Arizona and Kansas branch sales during the fourth quarter of 2025 which consisted of $641.6 million of deposits.

Other borrowed funds is composed of variable-rate, overnight and fixed-rate borrowings with remaining contractual tenors of up to one year through the Federal Home Loan Bank. Other borrowed funds were zero as of March 31, 2026 and December 31, 2025, respectively. Other borrowed funds decreased $960.0 million from March 31, 2025. The decrease was funded by cash flows from paydowns and maturities of investment securities and loans.

The Company is considered to be "well-capitalized" as of March 31, 2026, having exceeded all regulatory capital adequacy requirements. During the first quarter of 2026, the Company paid regular common stock dividends of approximately $45.7 million, or $0.47 per share and repurchased approximately 2.4 million shares of common stock at a weighted average price of $35.09 per share pursuant to its stock repurchase program.

CREDIT QUALITY

As of March 31, 2026, non-performing assets increased $24.2 million, or 17.5%, to $162.5 million, compared to $138.3 million as of December 31, 2025, primarily as a result of an increase in non-accrual loans related to a single client relationship comprised of $20.2 million in commercial and commercial real estate non-accrual loans and an increase of $3.2 million in OREO.

Criticized loans decreased $18.6 million, or 1.8%, to $1,033.2 million as of March 31, 2026, from $1,051.8 million as of December 31, 2025, primarily as a result of upgrades as well as paydowns and payoffs in the portfolio.

NON-GAAP FINANCIAL MEASURES

In addition to results presented in accordance with accounting principles generally accepted in the United States of America, or GAAP, this press release contains the following non-GAAP financial measures that management uses to evaluate our performance relative to our capital adequacy standards: (i) tangible common stockholders' equity; (ii) tangible assets; (iii) tangible book value per common share; (iv) tangible common stockholders' equity to tangible assets; (v) average tangible common stockholders' equity; (vi) return on average tangible common stockholders' equity; (vii) net FTE interest income; (viii) net FTE interest margin ratio; (ix) adjusted net FTE interest income; and (x) adjusted net FTE interest margin ratio. Tangible common stockholders' equity is calculated as total common stockholders' equity less goodwill and other intangible assets (excluding mortgage servicing rights). Tangible assets are calculated as total assets less goodwill and other intangible assets (excluding mortgage servicing rights). Tangible book value per common share is calculated as tangible common stockholders' equity divided by common shares outstanding. Tangible common stockholders' equity to tangible assets is calculated as tangible common stockholders' equity divided by tangible assets. Average tangible common stockholders' equity is calculated as average total stockholders' equity less average goodwill and other intangible assets (excluding mortgage servicing rights). Return on average tangible common stockholders' equity is calculated as annualized net income available to common shareholders divided by average tangible common stockholders' equity. Net FTE interest income is calculated as net interest income, adjusted to include its FTE interest income. Net FTE interest margin ratio is calculated as net FTE interest income divided by average interest earning assets. Adjusted net FTE interest income is calculated as net FTE interest income less purchase accounting interest accretion on acquired loans. Adjusted net FTE interest margin ratio is calculated as annualized adjusted net FTE interest income divided by average interest earning assets. These non-GAAP financial measures may not be comparable to similarly titled measures reported by other companies because other companies may not calculate these non-GAAP measures in the same manner. They also should not be considered in isolation or as a substitute for measures prepared in accordance with GAAP.

The Company adjusts the most directly comparable capital adequacy GAAP financial measures to the non-GAAP financial measures described in subclauses (i) through (vi) above to exclude goodwill and other intangible assets (except mortgage servicing rights), adjusts its GAAP net interest income to include fully taxable equivalent adjustments and further adjusts its net interest income on a fully taxable equivalent basis to exclude purchase accounting interest accretion. Management believes these non-GAAP financial measures, which are intended to complement the capital ratios defined by banking regulators and to present on a consistent basis our and our acquired companies' organic continuing operations without regard to acquisition costs and other adjustments that we consider to be unpredictable and dependent on a significant number of factors that are outside our control, are useful to investors in evaluating the Company's performance because, as a general matter, they either do not represent an actual cash expense and are inconsistent in amount and frequency depending upon the timing and size of our acquisitions (including the size, complexity and/or volume of past acquisitions, which may drive the magnitude of acquisition related costs, but may not be indicative of the size, complexity and/or volume of future acquisitions or related costs), or they cannot be anticipated or estimated in a particular period (in particular as it relates to unexpected recovery amounts). This impacts the ratios that are important to analysts and allows investors to compare certain aspects of the Company's capitalization to other companies.

See the "Non-GAAP Financial Measures" table included herein and the textual discussion for a reconciliation of the above-described non-GAAP financial measures to their most directly comparable GAAP financial measures.

Cautionary Note Regarding Forward-Looking Statements and Factors that Could Affect Future Results

This press release contains "forward-looking statements" within the meaning of Section 27A of the Securities Act of 1933, as amended, and Rule 175 promulgated thereunder, and Section 21E of the Securities Exchange Act of 1934, as amended, or the Exchange Act, and Rule 3b-6 promulgated thereunder, that involve inherent risks and uncertainties. Any statements about our plans, objectives, expectations, strategies, beliefs, or future performance, financial condition, results of operations, investment portfolio, market position, or events constitute forward-looking statements. Such statements are identified by words or phrases such as "believes," "expects," "anticipates," "plans," "trends," "objectives," "continues", "projected," as well as the negative forms of those words or similar expressions, or future or conditional verbs such as "will," "would," "should," "could," "might," "may," or similar expressions. Forward-looking statements involve known and unknown risks, uncertainties, assumptions, estimates and other important factors that could cause actual results to differ materially from any results, performance or events expressed or implied by such forward-looking statements. Furthermore, the following factors, among others, may cause actual results to differ materially from current expectations in the forward-looking statements, including those set forth in this press release:

new or changes in existing governmental regulations or in the way such regulations are interpreted or enforced;
negative developments in the banking industry and increased regulatory scrutiny;
tax legislative initiatives or assessments;
more stringent capital requirements, to the extent they may become applicable to us;
changes in accounting standards;
any failure to comply with applicable laws and regulations, including, but not limited to, the Community Reinvestment Act and fair lending laws, the USA PATRIOT ACT of 2001, the Office of Foreign Asset Control guidelines and requirements, the Bank Secrecy Act, and the related Financial Crimes Enforcement Network and Federal Financial Institutions Examination Council Guidelines and regulations;
federal deposit insurance assessment rate increases;
lending risks and risks associated with loan portfolio concentrations;
a decline in economic conditions that could reduce demand for our products and services and negatively impact the credit quality of loans;
credit losses on loans exceeding estimates;
potential effects on the U.S. economy resulting from the implementation of governmental policies, including tax regulations and changes to United States trade policies, including the imposition of tariffs and retaliatory tariffs and geopolitical uncertainty;
the soundness of other financial institutions;
the ability to meet cash flow needs and availability of financing sources for working capital and other needs;
a loss of deposits or a change in product mix that increases the Company's funding costs;
inability to access funding or to monetize liquid assets;
changes in interest rates;
interest rate effect on the value of our investment securities;
cybersecurity risks, including business disruptions from denial-of-service attacks, network intrusions, business e-mail compromise, and other malicious behavior that could result in the disclosure of confidential information;
privacy, information security, and data protection laws, rules, and regulations that affect or limit how we collect and use personal information or otherwise have an adverse effect on us;
the potential impairment of our goodwill and other intangible assets;
our reliance on third parties that provide key components of our business infrastructure;
events that may tarnish our reputation;
mainstream and social media contagion;
the loss of the services of key members of our management team and directors;
our ability to attract and retain qualified employees to operate our business;
costs associated with repossessed properties, including potential environmental remediation;
the effectiveness of our operational processes, policies and procedures, and internal control over financial reporting;
our ability to implement technology-facilitated products and services or be successful in marketing these products and services to our clients;
the development and use of artificial intelligence ("AI");
risks related to acquisitions, mergers, strategic partnerships, divestitures, and other transactions;
competition from new or existing financial institutions and non-banks;
investing in technology;
incurrence of significant costs related to mergers and related integration activities;
the volatility in the price and trading volume of our common stock;
"anti-takeover" provisions in our certificate of incorporation and regulations, which may make it more difficult for a third party to acquire control of us even in circumstances that could be deemed beneficial to stockholders;
changes in our dividend policy or our ability to pay dividends;
the possibility that we may fail to realize the anticipated benefits of our stock repurchase program;
our common stock not being an insured deposit;
the potential dilutive effect of future equity issuances;
the subordination of our common stock to our existing and future indebtedness;
the effect of global conditions, earthquakes, volcanoes, tsunamis, floods, fires, drought, and other natural catastrophic events; and
the impact of climate change and environmental sustainability matters.

The foregoing factors are not necessarily all of the factors that could cause our actual results, performance, or achievements to differ materially from expectations. Other unknown or unpredictable factors also could harm our results.

All forward-looking statements attributable to us or persons acting on our behalf are expressly qualified in their entirety by the cautionary statements set forth above and included and described in more detail in our periodic reports filed with the Securities and Exchange Commission, or SEC, under the Securities Exchange Act of 1934, as amended, under the caption "Risk Factors." Interested parties are urged to read in their entirety such risk factors prior to making any investment decision with respect to the Company. Forward-looking statements speak only as of the date they are made, and we do not undertake or assume any obligation to update publicly any of these statements to reflect actual results, new information or future events, changes in assumptions or changes in other factors affecting forward-looking statements, except to the extent required by applicable laws. If we update one or more forward-looking statements, no inference should be drawn that we will make additional updates with respect to those or other forward-looking statements.

First Quarter 2026 Conference Call for Investors

First Interstate BancSystem, Inc. will host a conference call to discuss the results for the first quarter of 2026 at 9:30 a.m. Eastern Time (7:30 a.m. Mountain Time) on Thursday, April 30, 2026. The conference call will be accessible by telephone and through the Internet. Participants may join the call by dialing 1-800-715-9871; the access code is 5906009. To participate via the Internet, visit www.FIBK.com. The call will be recorded and made available for replay on April 30, 2026, after 1:00 p.m. Eastern Time (11:00 a.m. Mountain Time), through May 30, 2026, prior to 9:00 a.m. Eastern Time (7:00 a.m. Mountain Time), by dialing 1-800-770-2030; the access code is 5906009. The call will also be archived on our website, www.FIBK.com, for one year.

About First Interstate BancSystem, Inc.

First Interstate BancSystem, Inc. is a financial and bank holding company focused on community banking. Incorporated in 1971 and headquartered in Billings, Montana, the Company operates banking offices, including detached drive-up facilities, in communities across Colorado, Idaho, Iowa, Missouri, Montana, Nebraska, Oregon, South Dakota, Washington, and Wyoming, in addition to offering online and mobile banking services. Through our bank subsidiary, First Interstate Bank, the Company delivers a comprehensive range of banking products and services to individuals, businesses, municipalities, and others throughout the Company's market areas.

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES Consolidated Statements of Income (Unaudited)

	Quarter Ended												% Change
*(In millions, except % and per share data)*	Mar 31, 2026			Dec 31, 2025		Sep 30, 2025		Jun 30, 2025			Mar 31, 2025		1Q26 vs 4Q25		1Q26 vs 1Q25
Net interest income	$	200.7		$	206.4	$	206.8	$	207.2		$	205.0	(2.8	)%	(2.1	)%
Net interest income on a fully-taxable equivalent ("FTE") basis		202.0			207.7		208.2		208.6			206.6	(2.7	)	(2.2	)
Provision for (reduction of) credit losses		6.7			7.1		—		(0.3	)		20.0	(5.6	)	(66.5	)
Noninterest income:
Payment services revenues		15.6			16.2		16.8		17.8			17.1	(3.7	)	(8.8	)
Mortgage banking revenues		1.3			1.1		1.5		1.8			1.4	18.2		(7.1	)
Wealth management revenues		10.5			10.7		10.4		9.7			9.8	(1.9	)	7.1
Service charges on deposit accounts		6.5			6.5		7.0		6.9			6.6	—		(1.5	)
Other service charges, commissions, and fees		2.1			2.3		2.1		2.1			2.3	(8.7	)	(8.7	)
Total fee-based revenues		36.0			36.8		37.8		38.3			37.2	(2.2	)	(3.2	)
Other income		5.1			69.8		5.9		2.8			4.8	(92.7	)	6.3
Total noninterest income		41.1			106.6		43.7		41.1			42.0	(61.4	)	(2.1	)
Noninterest expense:
Salaries and wages		68.5			74.8		66.2		65.0			68.6	(8.4	)	(0.1	)
Employee benefits		21.2			18.5		18.2		17.9			20.0	14.6		6.0
Occupancy and equipment		18.6			19.6		18.5		18.6			18.7	(5.1	)	(0.5	)
Other intangible amortization		3.3			3.4		3.4		3.4			3.4	(2.9	)	(2.9	)
Other expenses		47.1			50.4		51.6		50.2			49.4	(6.5	)	(4.7	)
Other real estate owned expense, net		(1.1	)		—		—		—			0.5	NM		NM
Total noninterest expense		157.6			166.7		157.9		155.1			160.6	(5.5	)	(1.9	)
Income before income tax		77.5			139.2		92.6		93.5			66.4	(44.3	)	16.7
Provision for income tax		17.3			30.4		21.2		21.8			16.2	(43.1	)	6.8
Net income	$	60.2		$	108.8	$	71.4	$	71.7		$	50.2	(44.7	)%	19.9	%

Weighted-average basic shares outstanding		98,881			100,791		103,154		103,261			103,092	(1.9	)%	(4.1	)%
Weighted-average diluted shares outstanding		99,241			101,096		103,387		103,364			103,416	(1.8	)	(4.0	)
Earnings per share - basic	$	0.61		$	1.08	$	0.69	$	0.69		$	0.49	(43.5	)	24.5
Earnings per share - diluted		0.61			1.08		0.69		0.69			0.49	(43.5	)	24.5

NM - not meaningful

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES\| Consolidated Balance Sheets (Unaudited)

																% Change
*(In millions, except % and per share data)*	Mar 31, 2026			Dec 31, 2025			Sep 30, 2025			Jun 30, 2025			Mar 31, 2025			1Q26 vs 4Q25		1Q26 vs 1Q25
Assets:
Cash and due from banks	$	321.7		$	358.2		$	382.7		$	436.6		$	390.4		(10.2	)%	(17.6	)%
Interest bearing deposits in banks		886.9			951.4			1,066.4			653.5			480.9		(6.8	)	84.4
Federal funds sold		0.1			0.1			0.1			0.1			0.1		—		—
Cash and cash equivalents		1,208.7			1,309.7			1,449.2			1,090.2			871.4		(7.7	)	38.7
Investment securities, net		8,010.0			7,630.2			7,305.8			7,312.2			7,503.8		5.0		6.7
Investment in Federal Home Loan Bank and Federal Reserve Bank stock		106.3			106.3			106.8			118.1			150.1		NM		(29.2	)
Loans held for sale, at fair value		70.8			73.6			305.6			335.2			0.4		(3.8	)	NM
Loans held for investment		14,728.4			15,201.6			15,834.4			16,353.4			17,377.3		(3.1	)	(15.2	)
Allowance for credit losses		(195.8	)		(191.4	)		(205.8	)		(209.6	)		(215.3	)	2.3		(9.1	)
Net loans held for investment		14,532.6			15,010.2			15,628.6			16,143.8			17,162.0		(3.2	)	(15.3	)
Goodwill and intangible assets (excluding mortgage servicing rights)		1,178.9			1,182.2			1,185.5			1,188.9			1,192.4		(0.3	)	(1.1	)
Company owned life insurance		524.6			523.0			520.2			516.7			514.2		0.3		2.0
Premises and equipment		403.1			406.6			415.1			413.0			428.9		(0.9	)	(6.0	)
Other real estate owned		6.6			3.4			3.4			3.4			3.5		94.1		88.6
Mortgage servicing rights		22.5			23.1			23.8			24.4			24.9		(2.6	)	(9.6	)
Other assets		362.7			372.3			388.9			420.5			428.2		(2.6	)	(15.3	)
Total assets	$	26,426.8		$	26,640.6		$	27,332.9		$	27,566.4		$	28,279.8		(0.8	)%	(6.6	)%

Liabilities and stockholders' equity:
Deposits	$	21,883.0		$	22,088.3		$	22,605.0		$	22,630.6		$	22,732.8		(0.9	)%	(3.7	)%
Securities sold under repurchase agreements		476.1			479.6			485.2			509.3			528.0		(0.7	)	(9.8	)
Other borrowed funds		—			—			—			250.0			960.0		—		(100.0	)
Long-term debt		146.7			146.3			146.2			252.0			130.2		0.3		12.7
Subordinated debentures held by subsidiary trusts		149.9			149.8			163.1			163.1			163.1		0.1		(8.1	)
Other liabilities		412.6			329.6			484.7			339.6			404.4		25.2		2.0
Total liabilities		23,068.3			23,193.6			23,884.2			24,144.6			24,918.5		(0.5	)	(7.4	)
Stockholders' equity:
Common stock		2,265.5			2,350.9			2,439.3			2,463.5			2,460.2		(3.6	)	(7.9	)
Retained earnings		1,288.7			1,274.2			1,213.5			1,191.2			1,168.6		1.1		10.3
Accumulated other comprehensive loss		(195.7	)		(178.1	)		(204.1	)		(232.9	)		(267.5	)	9.9		(26.8	)
Total stockholders' equity		3,358.5			3,447.0			3,448.7			3,421.8			3,361.3		(2.6	)	(0.1	)
Total liabilities and stockholders' equity	$	26,426.8		$	26,640.6		$	27,332.9		$	27,566.4		$	28,279.8		(0.8	)%	(6.6	)%

Common shares outstanding at period end		98,820			101,106			103,967			104,874			104,910		(2.3	)%	(5.8	)%
Book value per common share at period end	$	33.99		$	34.09		$	33.17		$	32.63		$	32.04		(0.3	)	6.1
Tangible book value per common share at period end**		22.06			22.40			21.77			21.29			20.67		(1.5	)	6.7

**Non-GAAP financial measure - see "Non-GAAP Financial Measures" included herein for a reconciliation of book value per common share (GAAP) at period end to tangible book value per common share (non-GAAP) at period end.
NM - not meaningful

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES Loans and Deposits (Unaudited)

																% Change
*(In millions, except %)*	Mar 31, 2026			Dec 31, 2025			Sep 30, 2025			Jun 30, 2025			Mar 31, 2025			1Q26 vs 4Q25		1Q26 vs 1Q25

Loans held for investment:
Real Estate:
Commercial	$	8,040.5		$	8,144.4		$	8,496.4		$	8,750.9		$	9,196.1		(1.3	)%	(12.6	)%
Construction		669.1			837.2			960.8			1,004.6			1,097.3		(20.1	)	(39.0	)
Residential		2,084.3			2,108.8			2,136.0			2,157.5			2,161.4		(1.2	)	(3.6	)
Agricultural		619.2			629.0			623.0			635.6			678.1		(1.6	)	(8.7	)
Total real estate		11,413.1			11,719.4			12,216.2			12,548.6			13,132.9		(2.6	)	(13.1	)
Consumer:
Indirect		419.4			477.5			540.3			607.1			680.2		(12.2	)	(38.3	)
Direct		128.0			131.5			134.3			134.4			132.4		(2.7	)	(3.3	)
Credit card		—			—			—			—			74.2		—		(100.0	)
Total consumer		547.4			609.0			674.6			741.5			886.8		(10.1	)	(38.3	)
Commercial		2,342.9			2,359.6			2,447.4			2,529.9			2,770.6		(0.7	)	(15.4	)
Agricultural		426.8			520.2			495.5			541.4			595.8		(18.0	)	(28.4	)
Other		5.8			1.7			10.2			2.0			1.8		241.2		222.2
Deferred loan fees and costs		(7.6	)		(8.3	)		(9.5	)		(10.0	)		(10.6	)	(8.4	)	(28.3	)
Loans held for investment	$	14,728.4		$	15,201.6		$	15,834.4		$	16,353.4		$	17,377.3		(3.1	)%	(15.2	)%

Deposits:
Noninterest bearing	$	5,229.0		$	5,286.8		$	5,555.7		$	5,579.0		$	5,590.2		(1.1	)%	(6.5	)%
Interest bearing:
Demand		6,257.3			6,319.7			6,324.7			6,465.4			6,439.2		(1.0	)	(2.8	)
Savings		7,961.7			7,843.5			7,954.0			7,789.6			7,876.4		1.5		1.1
Time, $250 thousand and over		694.7			792.9			851.1			837.3			823.4		(12.4	)	(15.6	)
Time, other		1,740.3			1,845.4			1,919.5			1,959.3			2,003.6		(5.7	)	(13.1	)
Total interest bearing		16,654.0			16,801.5			17,049.3			17,051.6			17,142.6		(0.9	)	(2.9	)
Total deposits	$	21,883.0		$	22,088.3		$	22,605.0		$	22,630.6		$	22,732.8		(0.9	)%	(3.7	)%

Total core deposits ⁽¹⁾	$	21,188.3		$	21,295.4		$	21,753.9		$	21,793.3		$	21,909.4		(0.5	)%	(3.3	)%

⁽¹⁾ Core deposits are defined as total deposits less time deposits, $250 thousand and over, and brokered deposits.

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES Credit Quality (Unaudited)

																% Change
*(In millions, except %)*	Mar 31, 2026			Dec 31, 2025			Sep 30, 2025			Jun 30, 2025			Mar 31, 2025			1Q26 vs 4Q25		1Q26 vs 1Q25

Allowance for Credit Losses:
Allowance for credit losses	$	195.8		$	191.4		$	205.8		$	209.6		$	215.3		2.3	%	(9.1	)%
As a percentage of loans held for investment		1.33	%		1.26	%		1.30	%		1.28	%		1.24	%
As a percentage of non-accrual loans		126.49			143.37			113.33			108.77			112.19

Net loan charge-offs during quarter	$	2.4		$	22.1		$	2.3		$	5.8		$	9.0		(89.1	)%	(73.3	)%
Annualized as a percentage of average loans		0.06	%		0.56	%		0.06	%		0.14	%		0.21	%

Non-Performing Assets:
Non-accrual loans	$	154.8		$	133.5		$	181.6		$	192.7		$	191.9		16.0	%	(19.3	)%
Accruing loans past due 90 days or more		1.1			1.4			0.6			1.4			3.0		(21.4	)	(63.3	)
Total non-performing loans		155.9			134.9			182.2			194.1			194.9		15.6		(20.0	)
Other real estate owned		6.6			3.4			3.4			3.4			3.5		94.1		88.6
Total non-performing assets	$	162.5		$	138.3		$	185.6		$	197.5		$	198.4		17.5	%	(18.1	)%

Non-performing assets as a percentage of:
Loans held for investment and OREO		1.10	%		0.91	%		1.17	%		1.21	%		1.14	%
Total assets		0.61			0.52			0.68			0.72			0.70

Non-accrual loans to loans held for investment		1.05			0.88			1.15			1.18			1.10

Allowance for credit losses coverage of non-performing loans		125.59			141.88			112.95			107.99			110.47

Accruing Loans 30-89 Days Past Due	$	71.9		$	82.7		$	28.5		$	52.2		$	90.2		(13.1	)%	(20.3	)%

Criticized Loans:
Special Mention	$	544.1		$	566.3		$	697.5		$	744.9		$	543.6		(3.9	)%	0.1	%
Substandard		421.1			441.4			416.9			427.8			469.5		(4.6	)	(10.3	)
Doubtful		68.0			44.1			49.7			30.3			13.0		54.2		423.1
Total	$	1,033.2		$	1,051.8		$	1,164.1		$	1,203.0		$	1,026.1		(1.8	)%	0.7	%

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES Selected Ratios - Annualized (Unaudited)

	At or for the Quarter ended:
	Mar 31, 2026				Dec 31, 2025			Sep 30, 2025			Jun 30, 2025			Mar 31, 2025
Annualized Financial Ratios (GAAP)
Return on average assets		0.92	%			1.60	%		1.04	%		1.03	%		0.71	%
Return on average common stockholders' equity		7.08				12.40			8.22			8.46			6.07
Yield on average earning assets		4.63				4.67			4.73			4.76			4.75
Cost of average interest bearing liabilities		1.64				1.77			1.90			1.95			2.05
Interest rate spread		2.99				2.90			2.83			2.81			2.70
Efficiency ratio		63.81				52.17			61.68			61.10			63.64
Loans held for investment to deposit ratio		67.31				68.82			70.05			72.26			76.44

Annualized Financial Ratios - Operating (Non-GAAP)**
Net FTE interest margin ratio		3.43	%			3.38	%		3.36	%		3.32	%		3.22	%
Tangible book value per common share	$	22.06			$	22.40		$	21.77		$	21.29		$	20.67
Tangible common stockholders' equity to tangible assets		8.63	%			8.90	%		8.66	%		8.47	%		8.01	%
Return on average tangible common stockholders' equity		10.77				18.79			12.53			13.01			9.42

Consolidated Capital Ratios
Total risk-based capital to total risk-weighted assets		17.07	%	*		17.06	%		16.62	%		16.49	%		14.93	%
Tier 1 risk-based capital to total risk-weighted assets		14.30		*		14.38			13.90			13.43			12.53
Tier 1 common capital to total risk-weighted assets		14.30		*		14.38			13.90			13.43			12.53
Leverage Ratio		9.56		*		9.61			9.60			9.37			9.06

*Preliminary estimate - may be subject to change. The regulatory capital ratios presented include the assumption of the transitional method as a result of legislation by the United States Congress to provide relief for the economy and financial institutions in the United States from the COVID‑19 pandemic. The referenced relief ended on December 31, 2024, which allowed a total five-year phase-in of the impact of CECL on capital.
**Non-GAAP financial measures - see "Non-GAAP Financial Measures" included herein for a reconciliation of net interest margin (GAAP) to net FTE interest margin ratio (non-GAAP), book value per common share (GAAP) to tangible book value per common share (non-GAAP), average common stockholders' equity to average assets (GAAP) to tangible common stockholders' equity to tangible assets (non-GAAP), and return on average common stockholders' equity (GAAP) to return on average tangible common stockholders' equity.

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES Average Balance Sheets (Unaudited)

	Three Months Ended
	March 31, 2026							December 31, 2025							March 31, 2025
*(In millions, except %)*	Average Balance		Interest⁽³⁾			Average Rate		Average Balance		Interest⁽³⁾			Average Rate		Average Balance		Interest⁽³⁾			Average Rate
Interest earning assets:
Loans ⁽¹⁾	$	15,032.1	$	207.6		5.60	%	$	15,540.5	$	222.0		5.67	%	$	17,668.6	$	243.5		5.59	%
Investment securities
Taxable ⁽²⁾		7,705.1		55.2		2.91			7,355.2		50.7		2.73			7,464.3		51.3		2.79
Tax-exempt		176.0		0.8		1.84			178.7		0.9		2.00			182.6		0.9		2.00
Investment in FHLB and FRB stock		106.3		1.2		4.58			106.7		1.1		4.09			175.9		2.9		6.69
Interest bearing deposits in banks		848.7		7.8		3.73			1,177.0		11.8		3.98			567.5		6.3		4.50
Federal funds sold		0.1		—		—			0.1		—		—			0.1		—		—
Total interest earning assets	$	23,868.3	$	272.6		4.63	%	$	24,358.2	$	286.5		4.67	%	$	26,059.0	$	304.9		4.75	%
Noninterest earning assets		2,613.2							2,668.6							2,759.9
Total assets	$	26,481.5						$	27,026.8						$	28,818.9
Interest bearing liabilities:
Demand deposits	$	6,199.9	$	12.8		0.84	%	$	6,316.6	$	14.9		0.94	%	$	6,412.7	$	14.4		0.91	%
Savings deposits		7,876.9		32.7		1.68			7,882.6		35.7		1.80			7,800.3		35.7		1.86
Time deposits		2,556.5		19.1		3.03			2,685.8		21.9		3.24			2,863.0		25.0		3.54
Repurchase agreements		479.6		1.0		0.85			496.4		1.2		0.96			533.0		1.2		0.91
Other borrowed funds		—		—		—			—		—		NM			1,533.5		17.5		4.63
Long-term debt		146.5		2.6		7.20			146.3		2.5		6.78			132.0		1.7		5.22
Subordinated debentures held by subsidiary trusts		149.9		2.4		6.49			150.8		2.6		6.84			163.1		2.8		6.96
Total interest bearing liabilities	$	17,409.3	$	70.6		1.64	%	$	17,678.5	$	78.8		1.77	%	$	19,437.6	$	98.3		2.05	%
Noninterest bearing deposits		5,214.2							5,424.3							5,608.2
Other noninterest bearing liabilities		411.4							442.7							418.0
Stockholders' equity		3,446.6							3,481.3							3,355.1
Total liabilities and stockholders' equity	$	26,481.5						$	27,026.8						$	28,818.9
Net FTE interest income (non-GAAP)⁽⁴⁾			$	202.0						$	207.7						$	206.6
Less FTE adjustments ⁽³⁾				(1.3	)						(1.3	)						(1.6	)
Net interest income from consolidated statements of income			$	200.7						$	206.4						$	205.0
Interest rate spread						2.99	%						2.90	%						2.70	%
Net interest margin						3.41							3.36							3.19
Net FTE interest margin ratio (non-GAAP)⁽⁴⁾						3.43							3.38							3.22
Cost of funds, including noninterest bearing demand deposits ⁽⁵⁾						1.27							1.35							1.59

⁽¹⁾		Average loan balances include loans held for sale and loans held for investment, net of deferred fees and costs, which include non-accrual loans. Interest income includes amortization of deferred loan fees net of deferred loan costs, which is not material for the periods presented.
⁽²⁾		Includes average balance of unsettled trades on investment securities.
⁽³⁾		Management believes fully taxable equivalent, or FTE, interest income is useful to investors in evaluating the Company's performance as a comparison of the returns between a tax-free investment and a taxable alternative. The Company adjusts interest income and average rates for tax exempt loans and securities to an FTE basis utilizing a 21% tax rate.
⁽⁴⁾		Non-GAAP financial measure - see "Non-GAAP Financial Measures" included herein for a reconciliation to GAAP measures.
⁽⁵⁾		Calculated by dividing total annualized interest on interest bearing liabilities by the sum of total interest bearing liabilities plus noninterest bearing deposits.

FIRST INTERSTATE BANCSYSTEM, INC. AND SUBSIDIARIES Non-GAAP Financial Measures (Unaudited)


		As of or For the Quarter Ended
*(In millions, except % and per share data)*		Mar 31, 2026			Dec 31, 2025			Sep 30, 2025			Jun 30, 2025			Mar 31, 2025
Total common stockholders' equity (GAAP)	(A)	$	3,358.5		$	3,447.0		$	3,448.7		$	3,421.8		$	3,361.3
Less goodwill and other intangible assets (excluding mortgage servicing rights)			1,178.9			1,182.2			1,185.5			1,188.9			1,192.4
Tangible common stockholders' equity (Non-GAAP)	(B)	$	2,179.6		$	2,264.8		$	2,263.2		$	2,232.9		$	2,168.9

Total assets (GAAP)		$	26,426.8		$	26,640.6		$	27,332.9		$	27,566.4		$	28,279.8
Less goodwill and other intangible assets (excluding mortgage servicing rights)			1,178.9			1,182.2			1,185.5			1,188.9			1,192.4
Tangible assets (Non-GAAP)	(C)	$	25,247.9		$	25,458.4		$	26,147.4		$	26,377.5		$	27,087.4

Average Balances:
Total common stockholders' equity (GAAP)	(D)	$	3,446.6		$	3,481.3		$	3,447.8		$	3,401.1		$	3,355.1
Less goodwill and other intangible assets (excluding mortgage servicing rights)			1,180.3			1,183.7			1,187.1			1,190.5			1,193.9
Average tangible common stockholders' equity (Non-GAAP)	(E)	$	2,266.3		$	2,297.6		$	2,260.7		$	2,210.6		$	2,161.2

Net interest income (GAAP)	(F)	$	200.7		$	206.4		$	206.8		$	207.2		$	205.0
FTE interest income			1.3			1.3			1.4			1.4			1.6
Net FTE interest income (Non-GAAP)	(G)		202.0			207.7			208.2			208.6			206.6
Less purchase accounting accretion on acquired loans			3.1			2.6			3.5			4.2			4.7
Adjusted net FTE interest income (Non-GAAP)	(H)	$	198.9		$	205.1		$	204.7		$	204.4		$	201.9

Average interest earning assets	(I)	$	23,868.3		$	24,358.2		$	24,589.5		$	25,180.1		$	26,059.0
Total quarterly average assets	(J)		26,481.5			27,026.8			27,292.4			27,898.4			28,818.9
Annualized net income available to common shareholders	(K)		244.1			431.7			283.3			287.6			203.6
Common shares outstanding	(L)		98,820			101,106			103,967			104,874			104,910

Return on average assets (GAAP)	(K) / (J)		0.92	%		1.60	%		1.04	%		1.03	%		0.71	%
Return on average common stockholders' equity (GAAP)	(K) / (D)		7.08			12.40			8.22			8.46			6.07
Average common stockholders' equity to average assets (GAAP)	(D) / (J)		13.02			12.88			12.63			12.19			11.64
Book value per common share (GAAP)	(A) / (L)	$	33.99		$	34.09		$	33.17		$	32.63		$	32.04
Tangible book value per common share (Non-GAAP)	(B) / (L)		22.06			22.40			21.77			21.29			20.67
Tangible common stockholders' equity to tangible assets (Non-GAAP)	(B) / (C)		8.63	%		8.90	%		8.66	%		8.47	%		8.01	%
Return on average tangible common stockholders' equity (Non-GAAP)	(K) / (E)		10.77			18.79			12.53			13.01			9.42
Net interest margin (GAAP)	(F*) / (I)		3.41			3.36			3.34			3.30			3.19
Net FTE interest margin ratio (Non-GAAP)	(G*) / (I)		3.43			3.38			3.36			3.32			3.22
Adjusted net FTE interest margin ratio (Non-GAAP)	(H*) / (I)		3.38			3.34			3.30			3.26			3.14

*Annualized

View source version on businesswire.com: https://www.businesswire.com/news/home/20260429682336/en/

David P. Della Camera, CFA

Chief Financial Officer

First Interstate BancSystem, Inc.

(406) 255-5363

investor.relations@fib.com

NASDAQ: FIBK

www.FIBK.com

(FIBK-ER)

First Interstate BancSystem, Inc. Reports First Quarter Earnings