12 Alt-A MBS Classes Downgraded

Twelve classes from two residential mortgage-backed securities deals backed by alternative-A mortgage loan collateral issued in 2005 have been downgraded by Standard & Poor's Ratings Services. S&P also removed all the ratings from Credit Watch with negative implications and affirmed the ratings on 13 other classes. The rating agency attributed the downgrades to "our opinion that projected credit support for the affected classes is insufficient to maintain the previous ratings given the current delinquency and loss levels for these transactions and our projection of future losses." Both transactions -- Nomura Asset Acceptance Corp. Alternative Loan Trust series 2005-AR6, and RALI series 2005-QA6 -- are backed by "a significant percentage" of adjustable-rate loans with initial reset periods of three years or less, S&P said.