(Bloomberg News) U.S. banks increased sales of insurance against credit losses to holders of Greek, Portuguese, Irish, Spanish and Italian debt in the first half of 2011, boosting the risk of payouts in the event of defaults.

Guarantees provided by U.S. lenders on government, bank and corporate debt in those countries rose by $80.7 billion to $518 billion, according to the Bank for International Settlements. Almost all of those are credit-default swaps, said two people familiar with the numbers, accounting for two-thirds of the total related to the five nations, BIS data show.

The payout risks are higher than what JPMorgan Chase & Co., Morgan Stanley and Goldman Sachs Group Inc., the leading CDS underwriters in the U.S., report. The banks say their net positions are smaller because they purchase swaps to offset ones they're selling to other companies. With banks on both sides of the Atlantic using derivatives to hedge, potential losses aren't being reduced, said Frederick Cannon, director of research at New York-based investment bank Keefe, Bruyette & Woods Inc.

"Risk isn't going to evaporate through these trades," Cannon said. "The big problem with all these gross exposures is counterparty risk. When the CDS is triggered due to default, will those counterparties be standing? If everybody is buying from each other, who's ultimately going to pay for the losses?"

Hedging Strategies

Similar hedging strategies almost failed in 2008 when American International Group Inc. couldn't pay insurance on mortgage debt. So far, banks that sold protection on sovereign debt have bet the right way. Last week, European leaders persuaded bondholders to participate in a restructuring that will likely avert a Greek default triggering payments. A CDS is a contract that requires one party to pay another for the face value of a bond if the issuer defaults.

The CDS holdings of U.S. banks are almost three times as much as their $181 billion in direct lending to the five countries at the end of June, according to the most recent data available from BIS. Adding CDS raises the total risk to $767 billion, a 20 percent increase over six months, the data show. BIS doesn't report which firms sold how much, or to whom.

The jump in CDS sold by U.S. banks on Greek, Portuguese, Irish and Spanish debt was almost the same as the decline in the exposure of German and U.K. lenders. German and U.K. risk related to Italy didn't fall, even as the amount of CDS sold by U.S. lenders on debt related to that country rose.

Five Banks

Five banks -- JPMorgan, Morgan Stanley, Goldman Sachs, Bank of America Corp. and Citigroup Inc. -- write 97 percent of all credit-default swaps in the U.S., according to the Office of the Comptroller of the Currency. The five firms had total net exposure of $45 billion to the debt of Greece, Portugal, Ireland, Spain and Italy, according to disclosures the companies made at the end of the third quarter. Spokesmen for the five banks declined to comment for this story.

While the lenders say in their public disclosures they have so-called master netting agreements with counterparties on the CDS they buy and sell, they don't identify those counterparties. About 74 percent of CDS trading takes place among 20 dealer- banks worldwide, including the five U.S. lenders, according to data from Depository Trust & Clearing Corp., which runs a central registry for over-the-counter derivatives.

In theory, if a bank owns $50 billion of Greek bonds and has sold $50 billion of credit protection on that debt to clients while buying $90 billion of CDS from others, its net exposure would be $10 billion. This is how some banks tried to protect themselves from subprime mortgages before the 2008 crisis. Goldman Sachs and other firms had purchased protection from New York-based insurer AIG, allowing them to subtract the CDS on their books from their reported subprime holdings.