FIRST INTERSTATE BANCSYSTEM INC (FIBK)

All Other Awards Equity award

Lorrie F. Asker — Transition and Separation Agreement | Original employment agreement effective August 24, 2023 with initial base salary of $440,000; Appointed Co-Chief Banking Officer effective September 10, 2025; Mutual decision to terminate Co-CBO role on November 14, 2025; Transitioned to Executive Advisor role to the CEO through March 31, 2026; LTI awards continued vesting through March 31, 2026; Separation treated as involuntary termination under employment agreement; Entitled to severance: 1x base salary + 1x average of 3-year prior annual incentive; Non-solicitation and non-competition for 12 months post-departure

David P. Della Camera — Employment Agreement | Initial base salary: $500,000 per year; 1-year term with automatic 1-year renewals (90-day notice to terminate); Termination without cause: 1x base salary + 1x average of 3-year prior annual incentive; 12 months continued benefits; CIC termination: 2x base salary + 2x target STI + pro-rata target bonus; all unvested RSUs vest; PRSUs vest at target; 24 months continued benefits; 280G safe harbor (no gross-up); 12-18 month non-solicitation and non-competition restrictions

Marcy D. Mutch — Transition and Separation Agreement | Continued as EVP and CFO through May 31, 2025 (CFO Transition Period); Served as Executive Advisor June 1 - December 31, 2025; During CFO Transition Period: base salary continued; STI prorated based on actual performance; During Executive Advisor Period: base salary at end-of-CFO-period rate; STI target at 75% of prior target (80%); LTI awards continued vesting; Non-employee consultant through December 31, 2026; Non-solicitation and non-competition for 12 months post-termination; Original employment agreement effective December 14, 2021 with initial base salary of $467,250