.8 billion on subprime-related direct exposures . these positive revenues were partially offset by negative revenues of $ 1.5 billion on alt-a mortgages , $ 1.3 billion of write-downs on commercial real estate , and a negative $ 1.6 billion cva on the monoline insurers and fair value option liabilities . revenue was also affected by negative marks on private equity positions and write-downs on highly leveraged finance commitments