National dealt two-notch blow by S&P as BAM, Assured ratings affirmed

S&P Global Ratings on Monday delivered a two-notch downgrade to National Public Finance Guarantee Corp., and affirmed its AA ratings on both Build America Mutual, which had earlier been placed on negative watch, and Assured Guaranty.

S&P said it lowered its financial strength rating on National to A from AA-minus and its long-term counterparty credit rating on its parent company, MBIA Inc., to BBB from A-minus. MBIA's financial strength was affirmed by S&P at CCC.

Some market analysts said the cuts will prevent National from writing new business, which would leave only two active bond insurers.