FIRST INTERSTATE BANCSYSTEM INC

Item 2. Unregistered Sales of Equity Securities and Use of Proceeds

(a) There were no unregistered sales of equity securities during the three months ended March 31, 2026.

(b) Not applicable.

(c) The following table provides information with respect to purchases made of our common stock by or on behalf of us or any “affiliated purchasers” (as defined in Rule 10b-18(a)(3) under the Exchange Act), during the three months ended March 31, 2026.

(1) On August 28, 2025, the board of directors of the Company adopted a new stock repurchase program. Under the stock repurchase program, the Company was provided authorization to repurchase up to $150.0 million of its issued and outstanding shares of common stock on or prior to March 31, 2027, which is the expiration date of the program. On January 27, 2026, the Board authorized an increase to the repurchase program of an additional $150.0 million of the Company’s issued and outstanding shares of common stock, bringing the total repurchase authorization since August 2025 to $300.0 million. Shares of common stock may be purchased through open market purchases, private transactions, block trades, authorized Rule 10b5-1 trading plans, or otherwise in accordance with applicable federal securities laws, including pursuant to Rule 10b-18 under the Exchange Act. Management’s decision to repurchase shares of common stock will depend on a number of factors, such as general market and economic conditions, the trading price of the common stock, alternative uses for capital, the Company’s financial performance, and corporate and regulatory requirements. See Part I, Item 2, “Management’s Discussion and Analysis of Financial Condition and Results of Operations — Capital Resources and Liquidity” for additional information.

(2)Stock repurchases were redemptions of vested restricted shares tendered in lieu of cash for payment of income tax withholding amounts by participants of the Company’s 2015 Equity and Incentive Plan.