Form 4 Filing for James A. Reuter

This filing details a transaction by James A. Reuter, President and CEO of FIRST INTERSTATE BANCSYSTEM INC. On March 15, 2026, Reuter acquired 31,392 shares of Common Stock, which were issued upon the vesting of restricted stock units granted under the company's 2023 Equity and Incentive Plan. These units vest in three equal annual installments starting March 15, 2027, contingent upon continued employment. The acquisition price was $33.13 per share, bringing Reuter's total post-transaction ownership to 92,029 shares. The transaction is reported on Form 4 and was signed by Kirk D. Jensen as attorney in fact.