Standard & Poor's placed 200 classes from 57 US cash flow and hybrid collateralized debt obligations of ABS and  CDO of CDO transactions. The amount of securities affected total approximately $25.96 billion. S&P says there is continued deterioration in the credit quality of residential MBS backing the CDO transactions. The rating action consists of 29 high grade CDOs of ABS, 22 mezzanine CDOs of ABS transactions and six CDOs of CDOs.