| # | Institution | Type | Branches | Deposits | Share |
|---|---|---|---|---|---|
| 1 | First Interstate Bank | Bank | 1 | $259.0M | 36.88% |
| 2 | Black Hills Federal Credit Union | Credit union | 1 | $101.4M* | 14.44% |
| 3 | First National Bank in Philip | Bank | 1 | $80.1M | 11.40% |
| 4 | Northern Hills Federal Credit Union | Credit union | 2 | $73.3M* | 10.43% |
| 5 | Pioneer Bank & Trust | Bank | 1 | $58.5M | 8.33% |
| 6 | Wells Fargo Bank, National Association | Bank | 1 | $53.8M | 7.66% |
| 7 | First National Bank | Bank | 1 | $39.0M | 5.55% |
| 8 | Sentinel Federal Credit Union | Credit union | 1 | $22.0M* | 3.14% |
| 9 | Dakota Plains Federal Credit Union | Credit union | 1 | $15.2M* | 2.16% |
* Credit-union deposits are estimated (June total shares spread evenly across branches).
| Year | Deposits | Institutions | Branches | Leader | Top share | HHI |
|---|---|---|---|---|---|---|
| 2026 | $702.3M | 9 | 10 | First Interstate Bank | 36.9% | 1,981 |
| 2025 | $657.1M | 9 | 10 | First Interstate Bank | 37.1% | 1,997 |
| 2024 | $609.4M | 9 | 10 | First Interstate Bank | 37.9% | 2,062 |
| 2023 | $654.5M | 9 | 10 | First Interstate Bank | 34.7% | 1,938 |
| 2022 | $666.5M | 9 | 10 | First Interstate Bank | 34.4% | 1,936 |
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