Moody's Investors Service on Tuesday downgraded $650 million of residential mortgage-backed securities made up of alternative-A loans issued by Countrywide Financial in 2005.

The rating agency has downgraded tens of billions of dollars of residential mortgage-backed securities over the past several months as loan losses and delinquencies remain high, although recent data pointed to stabilization and even improvement.

In Tuesday's downgrade, Moody's cited its updated loss expectations on all alt-A loans from 2005 through 2007 issued in February.

Alt-A loans, those considered between prime and subprime, were generally issued to borrowers who did not document their income or assets.

Countrywide was acquired two years ago by Bank of America Corp. as loans soared and as Countrywide, once the nation's biggest mortgage company, was hurt by a constrained credit market.

Subscribe Now

Access to authoritative analysis and perspective and our data-driven report series.

14-Day Free Trial

No credit card required. Complete access to articles, breaking news and industry data.