First Interstate BancSystem
| First Interstate Bank | |
| Company type | Public | 
| Nasdaq: FIBK (Class A) Russell 2000 Component | |
| Industry | Financial services | 
| Founded | 1968, in Sheridan, Wyoming, United States | 
| Founder | Homer Scott, Sr. | 
| Headquarters | First Interstate Center Billings, Montana, US | 
| Number of locations | 307 (2022) | 
| Key people | |
| Products | Checking accounts Savings accounts Mortgage loans Commercial loans Insurance Treasury management Investments Escrow services Consumer finance | 
| Revenue | US$656 million (2021) | 
| US$259 million (2021) | |
| US$192 million (2021) | |
| Total assets | US$32.06 billion (2022) | 
| Total equity | US$1.99 billion (2021) | 
| Number of employees | 2,358 (2021) | 
| Website | firstinterstatebank | 
First Interstate BancSystem, Inc. is a financial holding company headquartered in Billings, Montana. It is the parent company of First Interstate Bank, a community bank with locations throughout 14 states within the Western and Midwestern United States. It is the largest bank based in Montana, as measured by total assets.