How ACA a company that provided bond insurance for Collaterized Debt Obligation or CDO's basically did not provide good insurance to the CDO issuers becase it did not have the financial resources necessary to do this but instead let banks and investment houses to benefit from the accounting rules in the insurance industry which allow another set of accounting rules different from GAAP (Geerally Accepted Accounting Principles). Under these rules banks and investment houses did not have to follow the mark to market rules of GAAP and could book the difference between interest payments and the insurance premium across the life of the bond (5-10 years), in the quarter they bough the insurance, what were essentially illusory profits. Merill Lynch issued a lot of these CDO's. In November 2007 ACA was forced to take $1 billion in losses for the third quarter. Standard and Poors downgraded ACA from A to CCC a month later. The downgrade forced ACA to come up with more collateral to show that it had the funds to back up its insurance. When it came short of funds Merrill Lynch, UBS, CIBC had to take big losses on these policies. This began the first big shocks on the Street at te end of 2007. Note that $43 billion in securities backed by risky corporate loans and bonds like the ones used for a lot of the buyouts have insurance from ACA. These could be the next to sour and lead to more writedowns as the economy weakens. ...