http://www.time.com/time/business/article/0,8599,1723152,00.html
The CDS market exploded over the past decade to more than $45 trillion in mid-2007, according to the International Swaps and Derivatives Association. This is roughly twice the size of the U.S. stock market (which is valued at about $22 trillion and falling) and far exceeds the $7.1 trillion mortgage market and $4.4 trillion U.S. treasuries market, notes Harvey Miller, senior partner at Weil, Gotshal & Manges. "It could be another — I hate to use the expression — nail in the coffin," said Miller, when referring to how this troubled CDS market could impact the country's credit crisis.

Credit default swaps are insurance-like contracts that promise to cover losses on certain securities in the event of a default. They typically apply to municipal bonds, corporate debt and mortgage securities and are sold by banks, hedge funds and others. The buyer of the credit default insurance pays premiums over a period of time in return for peace of mind, knowing that losses will be covered if a default happens. It's supposed to work similarly to someone taking out home insurance to protect against losses from fire and theft.