Marathon Bank is a Wisconsin-chartered community savings bank headquartered in Wausau, with five branches across Marathon, Ozaukee, and Waukesha Counties. Founded in 1902, Marathon Bank takes deposits from individuals and businesses and lends those funds out, primarily in real estate loans. The bank's core lending focus is commercial real estate (CRE) and multifamily loans, which together represent about 69% of the loan portfolio. Since 2014, Marathon Bank has actively shifted away from its original thrift identity toward commercial lending, expanding into Southeastern Wisconsin, including the Milwaukee metro area, where it opened branches in Mequon (2018) and Brookfield (2024). The bank also originates residential mortgages, holding adjustable-rate loans on its balance sheet and selling conforming fixed-rate loans to Fannie Mae and Freddie Mac on a servicing-retained basis. Marathon Bank earns primarily through net interest income — the spread between loan and securities yields and deposit and borrowing costs. Core deposits (checking, savings, money market) fund roughly 62% of deposits, and the bank uses FHLB advances to manage funding duration. The shift toward CRE and multifamily is deliberate: these loans carry higher yields and balloon structures that allow periodic repricing, reducing duration risk versus long-dated fixed-rate mortgages. In April 2025, Marathon Bancorp completed a conversion from a mutual holding company to a full stock company, raising ~$15M in net proceeds, with shares now trading on Nasdaq under "MBBC."