| # | Institution | Type | Branches | Deposits | Share |
|---|---|---|---|---|---|
| 1 | First Interstate Bank | Bank | 2 | $112.2M | 30.41% |
| 2 | Black Hills Federal Credit Union | Credit union | 1 | $101.4M* | 27.49% |
| 3 | Aspen Federal Credit Union | Credit union | 1 | $50.9M* | 13.79% |
| 4 | Highmark Federal Credit Union | Credit union | 1 | $47.0M* | 12.74% |
| 5 | Dacotah Bank | Bank | 1 | $35.4M | 9.59% |
| 6 | Sentinel Federal Credit Union | Credit union | 1 | $22.0M* | 5.97% |
* Credit-union deposits are estimated (June total shares spread evenly across branches).
| Year | Deposits | Institutions | Branches | Leader | Top share | HHI |
|---|---|---|---|---|---|---|
| 2026 | $369.0M | 6 | 7 | First Interstate Bank | 30.4% | 2,161 |
| 2025 | $319.2M | 5 | 6 | First Interstate Bank | 36.1% | 2,677 |
| 2024 | $292.9M | 5 | 5 | Black Hills Federal Credit Union | 34.2% | 2,569 |
| 2023 | $327.4M | 5 | 5 | Black Hills Federal Credit Union | 38.3% | 2,677 |
| 2022 | $337.8M | 5 | 5 | Black Hills Federal Credit Union | 39.4% | 2,786 |
Every institution above links to its profile — ratios, peer medians and this quarter’s change signals. Pro adds the full table, share movement and CSV export.