The Federal Housing Finance Agency is suing a unit of Deutsche Bank demanding the bank repurchase loans backing now toxic mortgage securities. Acting as conservator to Freddie Mac, the FHFA filed suit on Aug. 24 in New York State Supreme Court in Manhattan against DB Structured Products Inc. The Finance Agency alleges that DBSP breached promises about loans that were pooled and securitized and failed to repurchase the loans as required, according to the agency’s court filing.