Bank of Sun Prairie
Sun Prairie, Wisconsin, Dane County
$841M in total assets, the 1,229th largest of 4,309 US banks and 36th of 155 headquartered in Wisconsin.
- FDIC certificate
- 13565
- Established
- 1903
- Owned by
- Bosp Bancshares Inc
- Primary regulator
- FDIC
At a glance
Compared with 109 banks headquartered in Wisconsin with $100 million to $1 billion in assets, as of June 30, 2026.
| Measure | This bank | Percentile | Peer range, middle 90% | Peer median |
|---|---|---|---|---|
| Total assets | $841M | 97% | $344M | |
| Loans | $602M | 95% | $241M | |
| Deposits | $719M | 96% | $287M | |
| Return on assets | 0.66% | 13% | 1.28% | |
| Net interest margin | 2.89% | 6% | 3.86% | |
| Efficiency ratio | 77.9% | 88% | 60.7% | |
| Equity to assets | 10.03% | 43% | 10.40% | |
| Loans to deposits | 84% | 44% | 86% |
Growth
Total assets grew 9.3% a year over the last 5 years and 9.6% a year over 10 years, including 1 acquisition in the last 10 years.
Acquisitions
| Closed | Acquired bank | Assets at acquisition |
|---|---|---|
| May 2026 | Banner Banks Birnamwood, WI, an affiliate under the same holding company | $132M |
Where they operate
8 branches in 4 counties.
Largest markets by deposits
| County | Deposits | Market share | Rank |
|---|---|---|---|
| Dane County, WI | $606M | 2.3% | 14 of 33 |
| Marathon County, WI | $52M | 1.0% | 12 of 17 |
| Shawano County, WI | $33M | 5.2% | 7 of 8 |
| Langlade County, WI | $29M | 17.3% | 3 of 5 |
Deposits by branch from the FDIC Summary of Deposits, June 2026. Rank among all banks with branches in that county.
Branch history since 2016
Net gain of 4 branches since 2016 (4 to 8, +100.0%). 1 opened, 4 acquired, 1 closed or sold.
| Period | What happened | Opened or acquired | Closed or sold | Net change | Branches at end |
|---|---|---|---|---|---|
| Start of 2016 | Starting point | 4 | |||
| 2022 | Opened Sun Prairie | 1 | 0 | +1 | 5 |
| 2025 | Closed Sun Prairie | 0 | 1 | −1 | 4 |
| 2026 through Q2 | Acquired Banner Banks | 4 | 0 | +4 | 8 |
Balance sheet and earnings
Loans by type
| Type | Share | This bank | Peers |
|---|---|---|---|
| Commercial real estate | 43% | 28% | |
| Multifamily | 23% | 8% | |
| 1-4 family residential | 21% | 32% | |
| Business (C&I) | 6% | 10% | |
| Construction and land | 3% | 7% | |
| Farmland | 2% | 8% | |
| Agricultural | 1% | 2% | |
| Consumer | 1% | 2% | |
| Other | 0% | 2% |
Deposits by type
| Type | Share | This bank | Peers |
|---|---|---|---|
| Other interest-bearing | 60% | 48% | |
| Time deposits | 23% | 34% | |
| Noninterest-bearing | 17% | 19% |
Brokered deposits are 5.7% of deposits (peers 5.6%).
Return on assets
Trailing four quarters, with the peer median.
Credit and capital
| This bank | Peer median | |
|---|---|---|
| Noncurrent loans | 0.07% | 0.23% |
| Net charge-offs, annualized | -0.00% | 0.00% |
| Reserves to loans | 1.27% | 1.14% |
| Leverage ratio | 9.99% | 10.95% |
Noncurrent loans exclude government-guaranteed portions.
Related banks
Similar size in Wisconsin
Largest competitors in Dane County, WI
Figures as of June 30, 2026 from the bank's Call Report, FDIC structure and branch data, and the Federal Reserve. Short link: bankingstats.com/banks/bank-sun-prairie-wi