Lake Forest-based Wintrust Financial Corp., which operates 15 community banks in the Chicago and Milwaukee areas, said its mortgage unit has acquired certain assets and liabilities of River City Mortgage LLC.

Bloomington, Minn.-based River City was founded in 1994 and provides mortgage services throughout the Minneapolis area and the upper Midwest. It’s currently licensed to originate loans in five states, and has eight offices in Minnesota, Nebraska and North Dakota. It originated nearly $500 million in mortgage loans in 2010.

River City was founded by Louis Olsen, a past president of the Minnesota Brokers Association. He’ll assume the title of senior vice president at Wintrust Mortgage.

“This addition provides Wintrust Mortgage with a great opportunity to expand our presence throughout the Midwest and Great Lakes region,” David Hrobon, chief executive of Wintrust Mortgage, said in a statement.

Terms of the cash transaction aren’t being disclosed, but a “significant” part of the purchase price is conditioned on certain future profitability measures. The deal isn’t expected to have a material effect on Wintrust’s 2011 earnings per share.

Wintrust Mortgage was founded in 1981. Wintrust Financial has assets of $14 billion.