FIRST INTERSTATE BANCSYSTEM INC

Our principal executive offices and one of our banking offices are anchor tenants in an 18-story commercial building located in Billings, Montana. The building is owned by a joint venture limited liability company in which FIB owns a 50.0% interest. We lease approximately 100,000 square feet of office space in the building. We also own a building with approximately 66,000 square feet that houses our operations center in Billings, Montana. As of December 31, 2025, we provided banking services at 289 locations in Colorado, Idaho, Iowa, Minnesota, Missouri, Montana, Nebraska, North Dakota, Oregon, South Dakota, Washington, and Wyoming, of which 65 properties are leased from independent third parties, one property was leased from a related entity, and 223 physical properties are owned by us. We believe each of our facilities is suitable and adequate to meet our current operational needs.

As further described in Part I, Item 1. “Business,” we have entered into an agreement to sell 11 branches in Nebraska, which transaction is expected to close in the second quarter of 2026. Additionally, we opened one branch in Montana on February 2, 2026 and intend to close four additional Nebraska branches, one branch in Minnesota, and one branch in North Dakota at the end of February 2026.