Midwest BankCentre in Lemay, Mo., has agreed to buy Bremen Bank & Trust in Hazelwood, Mo.
The $1.6 billion-asset Midwest did not disclose the price of the all-cash deal, which is expected to close midsummer.
Midwest is privately held and the $175 million-asset Bremen's holding company, Bremen Bancorp, is thinly traded.
Bremen, founded in 1868, has four branches around St. Louis. Bremen opted to sell because of the challenges of running a small bank, Carl Fruend, the bank's president and chief executive, said in a press release.
"Changes in the banking environment have made it hard for small local banks to compete," Fruend said.
It would be the second acquisition in the past year for Midwest. It bought Southern Commercial Bank in St. Louis last April.