SAN FRANCISCO (MarketWatch) -- Standard & Poor's Ratings Services said late Tuesday it downgraded Ambac Assurance several notches to CC from BBB, or to junk status. S&P also cut the holding company's counterparty credit rating to CC from BB. The ratings were removed from review for a further downgrade and the outlook is negative. "This rating action reflects our view of the significant deterioration in Ambac's insured portfolio of nonprime residential mortgage-backed securities and related CDOs," said David Veno, an S&P credit analyst, in a statement. "This has required the company to strengthen reserves to account for higher projected claims. http://www.marketwatch.com/story/sp-downgrades-ambac-assurance-to-junk-2009-07-28