First Interstate BancSystem, Inc. FIBK Form 8-K filing Earnings

Exhibit 99.1

For Immediate Release

First Interstate BancSystem, Inc. Reports Second Quarter Earnings

Billings, MT - July 23, 2026 - First Interstate BancSystem, Inc. (NASDAQ: FIBK) (the “Company”) today reported financial results for the second quarter of 2026. For the quarter, the Company reported net income of $83.9 million, or $0.87 per diluted share, which compares to net income of $60.2 million, or $0.61 per diluted share, for the first quarter of 2026 and net income of $71.7 million, or $0.69 per diluted share, for the second quarter of 2025.

HIGHLIGHTS

• Completed the sale of eleven Nebraska branches on April 10, 2026 resulting in a gain of $19.5 million for the second quarter of 2026.
• Net interest margin increased to 3.45% for the second quarter of 2026, a 4-basis point increase from the first quarter of 2026 and a 15-basis point increase from the second quarter of 2025.
• Criticized loans decreased $95.8 million to $937.4 million as of June 30, 2026, compared to $1,033.2 million as of March 31, 2026, and decreased $265.6 million, compared to $1,203.0 million as of June 30, 2025.
• Net charge-offs increased $7.3 million to $9.7 million, or an annualized 0.27% of average loans outstanding, as of June 30, 2026, from $2.4 million, or an annualized 0.06% of average loans outstanding, as of March 31, 2026, and increased $3.9 million from $5.8 million, or an annualized 0.14% of average loans outstanding, as of June 30, 2025.
• Non-performing assets increased $2.5 million, or 1.5%, to $165.0 million as of June 30, 2026, from $162.5 million as of March 31, 2026 and decreased $32.5 million, or 16.5%, from $197.5 million as of June 30, 2025.
• Total deposits decreased $441.7 million, or 2.0%, to $21,441.3 million as of June 30, 2026, compared to $21,883.0 million as of March 31, 2026, across all interest bearing deposit categories during the second quarter of 2026, primarily driven by the sale of eleven Nebraska branches that included $244.2 million of deposits. Total deposits decreased $1,189.3 million, or 5.3%, compared to $22,630.6 million as of June 30, 2025, across all deposit categories, primarily driven by the Arizona and Kansas sold branches during the fourth quarter of 2025 that included $641.6 million of deposits in addition to the deposits sold with the eleven Nebraska sold branches.
• Other borrowed funds were zero as of June 30, 2026 and March 31, 2026 as compared to $250.0 million as of June 30, 2025.
• During the second quarter of 2026, the Company repurchased approximately 1.93 million shares of common stock for a total repurchase of $68.7 million. The Company has repurchased approximately 7.98 million shares of its common stock through June 30, 2026 for a total repurchase of $270.3 million since the board of directors authorized the repurchase program in August of 2025. As of June 30, 2026, approximately $29.7 million remained available for future purchases under the $300.0 million authorized. On July 22, 2026, the board of directors authorized a further increase to the repurchase program of an additional $150.0 million, or a total of $450.0 million authorized since its adoption in August of 2025.
• Common equity tier 1 capital ratio increased 24 basis points during the second quarter of 2026 to 14.54%, compared to the first quarter of 2026, primarily due to lower risk-weighted assets driven by lower loan balances, partially offset by shares repurchased during the second quarter of 2026.

“We are pleased to see continued improvement in our net interest margin and meaningful progress reducing criticized loans, as we remain focused on strengthening the quality and earnings power of the franchise,” said James A. Reuter, President and Chief Executive Officer of the Company. “We also continued to execute on our previously announced share repurchase authorization and are expanding that authorization, underscoring our commitment to shareholder returns. Production and underlying account growth improved during the quarter, although elevated prepayment activity offset this momentum in reported balances. Many of the outcomes reflect deliberate actions that improve the long-term value of the franchise. Through ongoing fixed asset repricing, disciplined capital deployment, operating model optimization, and continued investment in relationship growth, we are building a more efficient organization and remain confident in our ability to deliver improving returns over time.”

DIVIDEND DECLARATION

On July 22, 2026, the Company’s board of directors declared a dividend of $0.47 per common share, payable on August 14, 2026, to common stockholders of record as of August 4, 2026. The dividend equates to a 5.3% annualized yield based on the $35.40 per share average closing price of the Company’s common stock as reported on NASDAQ during the second quarter of 2026.

NET INTEREST INCOME

Net interest income increased $1.5 million to $202.2 million during the second quarter of 2026, compared to net interest income of $200.7 million during the first quarter of 2026. Net interest income decreased $5.0 million, or 2.4%, during the second quarter of 2026 compared to the second quarter of 2025. The quarterly increase from the first quarter of 2026 was primarily driven by lower interest expense on time deposits and higher investment balances and yields, partially offset by lower interest income due to reduced loan balances and interest earning assets as a result of the sale of eleven Nebraska branches. 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 and the sale of eleven Nebraska branches during the second quarter of 2026, which resulted in a reduction of net interest income in the second quarter of 2026.

Interest accretion attributable to the fair value of acquired loans, related to prior acquisitions, contributed to net interest income during the second quarter of 2026, the first quarter of 2026, and the second quarter of 2025, in the amounts of $3.5 million, $3.1 million, and $4.2 million, respectively.

Net interest margin ratio was 3.45% for the second quarter of 2026, compared to 3.41% during the first quarter of 2026, and 3.30% during the second quarter of 2025. Net FTE (fully-taxable equivalent) interest margin ratio¹ was 3.48% for the second quarter of 2026, compared to 3.43% during the first quarter of 2026, and 3.32% during the second quarter of 2025. Excluding interest accretion from the fair value of acquired loans, the adjusted net FTE interest margin ratio¹ was 3.42%, an increase of 4 basis points from the prior quarter, primarily driven by higher investment yields and lower rates on interest bearing time deposits, partially offset by lower average loan balances and higher security 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 16 basis points, primarily as a result of lower interest expense resulting from decreased deposit and other borrowed funds balances.

PROVISION FOR CREDIT LOSSES

During the second quarter of 2026, the Company recorded a reduction of provision for credit losses of $3.2 million. This compares to a provision for credit losses of $6.7 million and a reduction of provision for credit losses of $0.3 million during the first quarter of 2026 and the second quarter of 2025, respectively.

For the second quarter of 2026, net loan charge-offs were $9.7 million, or an annualized 0.27% of average loans outstanding, compared to net loan charge-offs of $2.4 million, or an annualized 0.06% of average loans outstanding, for the first quarter of 2026 and net loan charge-offs of $5.8 million, or an annualized 0.14% of average loans outstanding, for the second quarter of 2025. Net loan charge-offs in the second quarter of 2026 were composed of charge-offs of $14.0 million offset by recoveries of $4.3 million. Net loan charge-offs in the first quarter of 2026 were composed of charge-offs of $6.5 million, which were offset by recoveries of $4.1 million. Net loan charge-offs in the second quarter of 2025 were composed of charge-offs of $13.0 million, which were offset by recoveries of $7.2 million.

The Company’s allowance for credit losses as a percentage of period-end loans held for investment was 1.28% at June 30, 2026, compared to 1.33% at March 31, 2026 and 1.28% at June 30, 2025. Coverage of non-performing loans decreased to 114.1% at June 30, 2026, compared to 125.6% at March 31, 2026 and increased from 108.0% at June 30, 2025.

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.

Noninterest income was $61.7 million for the second quarter of 2026, increasing $20.6 million compared to the first quarter of 2026 and increasing $20.6 million compared to the second quarter of 2025. The increases from the first quarter of 2026 and the second quarter of 2025 were primarily due to the $19.5 million gain recorded in other income from the previously announced sale of the eleven Nebraska branches during the second quarter of 2026.

Payment services revenues increased $1.2 million and decreased $1.0 million during the second quarter of 2026 compared to the first quarter of 2026 and the second quarter of 2025, respectively. The linked quarter increase was primarily due to an increase in business credit card and debit card interchange revenues during the second quarter of 2026. The year-over-year decrease was mainly the result of lower consumer credit card interchange during the second quarter of 2026 as compared to the second quarter of 2025, related to the outsourcing of consumer credit cards in the second quarter of 2025.

The Company’s noninterest expense was $158.9 million for the second quarter of 2026, an increase of $1.3 million from the first quarter of 2026 and an increase of $3.8 million from the second quarter of 2025.

Salaries and wages expense decreased $3.6 million to $64.9 million during the second quarter of 2026 compared to the first quarter of 2026, primarily due to lower short-term incentive accruals of $1.6 million, lower salary and wages, and lower severance accruals during the second quarter of 2026. Salaries and wages expense decreased $0.1 million to $64.9 million during the second quarter of 2026 compared to $65.0 million during the second quarter of 2025.

Employee benefit expenses decreased $2.2 million to $19.0 million during the second quarter of 2026, compared to $21.2 million during the first quarter of 2026, primarily due to lower payroll taxes, partially offset by higher long-term incentives. Employee benefit expenses increased $1.1 million from $17.9 million during the second quarter of 2025, primarily due to higher health insurance costs during the second quarter of 2026.

Other expenses increased $6.0 million during the second quarter of 2026 compared to the first quarter of 2026, primarily due to an increase of $1.2 million in professional fees, $0.8 million in donations, $0.6 million in FDIC insurance premiums, and various other expense categories. Other expenses increased $2.9 million during the second quarter of 2026 compared to the second quarter of 2025, primarily due to an increase of $1.0 million in advertising expense.

Other real estate owned expense, net increased $1.7 million during the second quarter of 2026 compared to the first quarter of 2026, primarily due to a positive fair value adjustment to a commercial property during the first quarter of 2026. Other real estate owned expense, net increased $0.6 million during the second quarter of 2026 compared to the second quarter of 2025.

BALANCE SHEET

Total assets decreased $541.8 million, or 2.1%, to $25,885.0 million as of June 30, 2026, from $26,426.8 million as of March 31, 2026, primarily due to a decrease of $515.7 million in loans as a result of payoffs and paydowns, including $64.1 million of loans related to the sale of the eleven Nebraska branches during the second quarter of 2026. Total assets decreased $1,681.4 million from $27,566.4 million as of June 30, 2025, primarily due to a decrease of $2,405.1 million in loans which were partially driven by the sale of the branches in Arizona and Kansas during the fourth quarter of 2025 and the sale of eleven branches in Nebraska during the second quarter of 2026. The loan declines were partially offset by an increase in investment securities of $673.4 million.

Investment securities decreased $24.4 million to $7,985.6 million as of June 30, 2026, from $8,010.0 million as of March 31, 2026, primarily resulting from pay-downs, maturities, called securities, and a $10.4 million decrease in fair market values, partially offset by purchases of investment securities during the second quarter of 2026. Investment securities increased $673.4 million from $7,312.2 million as of June 30, 2025, primarily resulting from purchases of investment securities and a $38.5 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:

The decline in loans was impacted by $50.4 million of continued amortization of the indirect portfolio for which the Company stopped originating loans during the first quarter of 2025, and loan payoffs and paydowns.

The ratio of loans held for investment to deposits was 66.6%, as of June 30, 2026, compared to 67.3% as of March 31, 2026 and 72.3% as of June 30, 2025.

Total deposits decreased $441.7 million, or 2.0%, to $21,441.3 million as of June 30, 2026, from $21,883.0 million as of March 31, 2026, across all interest bearing deposit categories during the second quarter, primarily driven by the sale of eleven Nebraska branches that included $244.2 million of deposits. Total deposits decreased $1,189.3 million, or 5.3%, compared to $22,630.6 million as of June 30, 2025, across all deposit categories, primarily driven by the Arizona and Kansas sold branches that included $641.6 million of deposits in addition to the deposits sold with the eleven Nebraska sold branches.

Other borrowed funds is comprised 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 June 30, 2026 and March 31, 2026. Other borrowed funds decreased $250.0 million from June 30, 2025. The decrease was funded by cash flows from paydowns and maturities of loans.

The Company is considered to be “well-capitalized” as of June 30, 2026, having exceeded all regulatory capital adequacy requirements. During the second quarter of 2026, the Company paid regular common stock dividends of approximately $46.0 million, or $0.47 per share, and repurchased approximately 1.9 million shares of common stock at a weighted-average price of $35.61 per share pursuant to its stock repurchase program.

CREDIT QUALITY

As of June 30, 2026, non-performing assets increased $2.5 million, or 1.5%, to $165.0 million, compared to $162.5 million as of March 31, 2026, primarily as a result of an increase in non-accrual loans, partially offset by a decrease of $1.3 million in OREO.

Criticized loans decreased $95.8 million, or 9.3%, to $937.4 million as of June 30, 2026, from $1,033.2 million as of March 31, 2026, primarily as a result of payoffs and paydowns, as well as upgrades 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.

Second Quarter 2026 Conference Call for Investors

First Interstate BancSystem, Inc. will host a conference call to discuss the results for the second quarter of 2026 at 9:30 a.m. Eastern Time (7:30 a.m. Mountain Time) on Friday, July 24, 2026. The conference call will be accessible by telephone and through the Internet. Participants may join the call by dialing 1-833-461-5787; the access code is 544064138. To participate via the Internet, visit www.FIBK.com. The webcast call will be recorded and made available for replay on July 24, 2026, after 1:30 p.m. Eastern Time (11:30 a.m. Mountain Time), through July 23, 2027, prior to 9:00 a.m. Eastern Time (7:00 a.m. Mountain Time), by visiting http://events.q4inc.com/attendee/544064138. 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

Loans and Deposits

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Credit Quality

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Selected Ratios - Annualized

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Non-GAAP Financial Measures

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