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Plymouth County, IA Bank Deposit Market Share

American Bank, N.A. holds the largest share of deposits in Plymouth County, IA, 31.2%, followed by Primebank (27.0%) and Iowa State Bank (12.9%). 8 institutions hold $1.43B at 15 offices as of June 30, 2026, up 2.0% from 2025.

Institutions: 8 Offices: 15 Deposits: $1.43B Survey: FDIC Summary of Deposits, June 30, 2026

Largest share changes since 2025

Gained: Northwest Bank (0.81 points); Midstates Bank, N.A. (0.58 points); Primebank (0.49 points).

Lost: Iowa State Bank (-2.21 points); The Security National Bank of Sioux City, Iowa (-0.31 points); Peoples Bank (-0.06 points).

# Institution Offices Deposits Market share Share change from 2025 Deposit change
1 American Bank, N.A. 2 $445.0M 31.23% +0.34 pts 3.1%
2 Primebank 1 $384.3M 26.97% +0.49 pts 3.8%
3 Iowa State Bank 5 $184.5M 12.95% -2.21 pts -12.9%
4 Northwest Bank 1 $104.5M 7.33% +0.81 pts 14.5%
5 Midstates Bank, N.A. 2 $98.3M 6.90% +0.58 pts 11.3%
6 United Bank of Iowa 1 $83.3M 5.85% +0.36 pts 8.7%
7 Peoples Bank 2 $79.7M 5.60% -0.06 pts 0.8%
8 The Security National Bank of Sioux City, Iowa 1 $45.4M 3.19% -0.31 pts -7.0%

About this list

Deposits are those held at each institution's offices in Plymouth County as of June 30, 2026, from the FDIC Summary of Deposits, whatever state the institution is headquartered in. Market share is the institution's deposits divided by all deposits in the market. Shares are by bank charter, not rolled up to the holding company, and cover FDIC-insured institutions only, so credit unions are not included. Each office is placed in its county and metro area by the FDIC branch directory; the few offices the directory does not list are left out of the market and of every share.

Share change compares the institution's share in 2025 and 2026 in percentage points. Deposit change compares its deposits here in the two years and includes deposits that moved through mergers and branch sales; "New" means it had no offices here a year earlier. Offices that closed during the year are placed by their ZIP code or city.

Wider markets

Iowa deposits by institution Iowa bank directory

Other counties in Iowa

Polk CountyLinn CountyScott CountyJohnson CountyDubuque CountyWoodbury CountyStory CountySioux CountyBlack Hawk CountyDallas CountyPottawattamie CountyClayton CountyCerro Gordo CountyDes Moines CountyCass CountyCarroll CountyClinton CountyMarshall CountyLee CountyWarren CountyDickinson CountyMuscatine CountyWinneshiek CountyClay CountyMarion CountyHardin CountyBremer CountyO'brien CountyWashington CountyWebster CountyBuena Vista CountyKossuth CountyGrundy CountyDelaware CountyJasper CountyAllamakee CountyBenton CountyLyon CountyChickasaw CountyCrawford County

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