American International Group (AIG)
Before it collapsed, AIG, as measured by asset value, was the largest insurer in the world. But in September 2008, after its credit rating went down, AIG was caught without enough collateral for the credit default swaps it had sold to banks around the world, and was forced to accept a massive federal bailout package in order to forestall a collapse. As the size of the company's debts have grown, the U.S. government has readjusted the terms of the bailout, and gradually begun to take over parts of the company. A confidential AIG memo leaked to the press warns of systemic risk if AIG collapses, and pegged the notional value of its derivatives exposures at $1.6 trillion.