Chicago-based Guaranteed Rate will purchase the assets of Overland Park-based FirsTrust Mortgage. FirsTrust CEO Mark McDougald said in a statement that the purchase will allow FirsTrust to spend less time on administrative tasks and more time focusing on clients. Guaranteed Rate, one of the largest retail mortgage lenders in the U.S., was founded in 2000 and has about 175 U.S. offices. FLASHBACK: Education helps FirsTrust Mortgage soar as others plummet