http://www.nytimes.com...

"...an exploration of A.I.G.’s demise and its relationships with firms like Goldman offers important insights into the mystifying, virally connected — and astonishingly fragile — financial world that began to implode in recent weeks.

Although America’s housing collapse is often cited as having caused the crisis, the system was vulnerable because of intricate financial contracts known as credit derivatives, which insure debt holders against default. They are fashioned privately and beyond the ken of regulators — sometimes even beyond the understanding of executives peddling them.

Originally intended to diminish risk and spread prosperity, these inventions instead magnified the impact of bad mortgages like the ones that felled Bear Stearns and Lehman and now threaten the entire economy.

In the case of A.I.G., the virus exploded from a freewheeling little 377-person unit in London, and flourished in a climate of opulent pay, lax oversight and blind faith in financial risk models. It nearly decimated one of the world’s most admired companies, a seemingly sturdy insurer with a trillion-dollar balance sheet, 116,000 employees and operations in 130 countries.

“It is beyond shocking that this small operation could blow up the holding company,” said Robert Arvanitis, chief executive of Risk Finance Advisors in Westport, Conn. “They found a quick way to make a fast buck on derivatives based on A.I.G.’s solid credit rating and strong balance sheet. But it all got out of control.”