Stifel Financial’s CEO, Ron Kruszewski, told me a few months ago that his firm’s biggest need was to have some sort of link with a commercial bank. This morning, he filled that need by announcing the acquisition of First Service Financial, a small bank in Crestwood.

Furthermore, Stifel has lured John Dubinsky back to the banking industry. Dubinsky, a Stifel director, will be the bank’s chairman. Dubinsky is the former CEO of Mark Twain Bank  and  Mercantile Bank in St. Louis.

Kruszewski told me that Dubinsky would be a non-executive chairman, but that “John’s actually going to get in the saddle again to a certain extent.”  He said Stifel expects to expand the bank “prudently but quickly.”

Owning a bank, Kruszewski explained, lets Stifel meet more of its clients’ financial needs. “We have more than $30 billion of client assets that we manage,” he said. “Those clients also have liabilities, and with a bank we can make mortgages, home-equity loans and lines of credit. We need to be able to service our clients fully.”

Dubinsky’s involvement, though, portends a bank that may also be an aggressive commercial lender. Small-business lending was a particular strength of Mark Twain.