Financial services firm Fremont General Corp. said Wednesday night that  it filed for bankruptcy protection as part of its plan to sell its retail banking assets to CapitalSource Inc., the Associated Press reported yesterday. The bankruptcy filing was necessary to allow CapitalSource, a commercial lender, to complete the purchase of Fremont General’s retail banking operations. The filing will have no effect on operations at the bank or its branches. Fremont General said that both the California Department of Financial Institutions and Federal Deposit Insurance Corp. approved CapitalSource’s acquisition of the retail banking operations. Fremont General previously was one of the largest originators of subprime mortgages.