Credit default swaps

The buyer of a credit swap receives credit protection, whereas the seller of the swap guarantees the credit worthiness of the product. By doing this, the risk of default is transferred from the holder of the fixed income security to the seller of the swap.

A credit default swap resembles an insurance policy, as it can be used by a debt holder to hedge, or insure against a default under the debt instrument. However, because there is no requirement to actually hold any asset or suffer a loss, a credit default swap can also be used for speculative purposes and it is not generally considered insurance for regulatory purposes.

In one notorious case, a small hedge fund agreed to insure UBS AG (UBSN.VX: Quote, Profile, Research, Stock Buzz), the Swiss banking giant, from losses related to defaults on $1.3 billion of subprime mortgages for an annual premium of about $2 million.

The trouble was, the hedge fund set up a subsidiary to stand behind the guarantee -- and capitalized it with just $4.6 million. As long as the loans performed, the fund made a killing, raking in an annualized return of nearly 44 percent.

But in the summer of 2007, as home owners began to default, things got ugly. UBS demanded the hedge fund put up additional collateral. The fund balked. UBS sued.