In spite of this, municipal bond insurers such as Ambac Financial (ABK) and MBIA (MBI) are somehow still solvent.

FORBES: Municipal Bond Closed-End Funds Attractive

The two biggest companies in the bond insurance business are MBIA (30, MBI) and Ambac Financial Group (22, ABK) .

FORBES: Magazine Article

The two biggest companies in the bond insurance business are MBIA (30, MBI) and Ambac Financial Group (nyse: ABK - news - people ) (22, ABK) .

FORBES: Buy Some Insurance

Late Wednesday, Moody's Investors Service said it might downgrade Ambac's (nyse: ABK - news - people ) all-important triple-A financial-strength credit rating after the company forecast significantly higher-than-expected losses from insuring credit derivatives, many of them tied to subprime mortgages.

FORBES: You Should Worry About Ambac