S&P may downgrade 207 Alt-A RMBS

"Standard & Poor's said on Tuesday that it may downgrade 207 classes of Alt-A residential mortgage-backed securities because of rising delinquencies on the underlying home loans. The 207 classes, which represent so-called Alt-A mortgages with an original total balance of approximately $913.9 million, were put on CreditWatch Negative, S&P said. The underlying loans were offered from the beginning of October 2005 through the end of December 2006, the ratings agency noted. Roughly $455.4 billion of residential mortgage-backed securities backed by first-lien Alt-A loans were rated by S&P in that time. "The collateral underlying the Alt-A transactions has been experiencing high levels of severe delinquencies that have not abated," S&P said."