信用违约互换（CDS）是交易双方之间的一种信用衍生品合约，其中“买方”定期向“卖方”支付费用，以换取在第三方发生违约或“信用事件”时获得赔付的权利。它们与针对公司破产可能性的保险合约非常相似，尤其是针对作为CDS标的的“参考实体”公司的债券和公司债务。然而，与保险不同，一家公司可以被纳入CDS保障或成为CDS标的的次数没有限制。买方只需支付类似保险费的小额款项，就可能在标的公司破产时获得巨额意外利润。近期雷曼兄弟公司的破产引发了一次信用事件，最终导致以雷曼债务为标的所出具的CDS承担了每美元92美分的赔付责任。

A credit default swap (CDS) is a credit derivative contract between two counterparties, where the “buyer” makes periodic payments to the “seller” in exchange for the right to a payoff if there is a default or “credit event” regarding the failure of a third party. They are very similar to an insurance contract over the possibility of company failure particularly on the bonds and corporate debt of the “reference entity” company which is the subject of the CDS. Unlike insurance, however, there is no limit on the number of times that a company can be covered or subject to a CDS. In return for small payments like insurance premiums the buyer of the CDS could stand to make an enormous windfall profit in the event of the failure of the subject. The recent failure of Lehman Brothers caused a credit event which ultimately led to a 92 cents on the dollar liability on CDSs written on Lehman debt.

信用违约互换是交易量最大的信用衍生品。国际清算银行报告称，截至2007年6月，场外信用违约互换的名义未平仓金额为42.6万亿美元。到2007年底，信用违约互换合约的估计价值达60万亿美元。仅在美国，货币监理署报告称，截至2008年3月底，报告银行持有的未平仓信用衍生品名义金额为16.4万亿美元。（为了更好地理解这些数字，中央情报局《世界概况》估计2007年美国国内生产总值为13万亿美元。） 信用违约互换与其他类型保险的一个重要区别在于：购买保险的人无需持有被保险的债券或金融工具。只要债券违约，且签约银行没有倒闭，买方就能获得赔付。然而，债券的“保险人”并不在任何交易所受到监管，这类交易基本上游离于政府监管之外。投机者可以购买某公司债券的保险，然后大规模做空该公司的股票（即在不持有股票的情况下卖出），从而对公司施压，使其要么倒闭，要么使其信用违约互换的价值上涨。如果公司倒闭，投机者的回报可能极为丰厚。

Credit default swaps are the most widely traded credit derivative product. The Bank for International Settlements reported the notional amount on outstanding OTC credit default swaps to be $42.6 trillion in June 2007. By the end of 2007 there were an estimated USD 60 trillion worth of Credit Default Swap contracts. In the US alone, the Office of the Comptroller of the Currency reported the notional amount of outstanding credit derivatives from reporting banks to be $16.4 trillion at the end of March, 2008. (To put these numbers in perspective, the CIA World Fact Book estimated the US GDP for 2007 at $13 trillion)/ One large difference between credit default swaps and other types of insurance, is you do not need to own the bond or instrument being insured in order to obtain insurance on it. If the bond fails, then you get paid, provided the bank writing the contract does not fail. Yet the “insurer” of the bond is not regulated on any exchange and the transaction is largely beyond any government regulation. Speculators can make money by purchasing insurance on a company's bonds then short the stock (sell the stock without owning it) of the company in great quantity, causing pressure on the company to either fail or the value of their CDS to rise. If the company fails the returns can be enormous.

CDS市场存在大量投机性头寸，其规模远超它所对冲的企业债务。对于持有某参照公司企业债的人而言，为降低企业破产的风险而使用CDS，其动机尚可理解。然而，当CDS的名义金额达到现存债务的数倍时，很明显，大量投机者是在赌公司倒闭，而非寻求分散风险。以雷曼兄弟为例，其债务总额为1500亿美元，而市场上发行的CDS合约却达4000亿美元。这个规模达60万亿美元的"大规模杀伤性武器"市场，已将赌博推向了前所未有的新高度。

There is a massive overhang of speculative positions in CDS – the market is dramatically larger than the corporate debt which it is covering. One can possibly understand the motive for mitigating the risks of corporate failure for those holding the corporate debt of the reference company. However, when CDS amount to several times the debt in existence it is clear that a large number of speculators are gambling over company failure rather than seeking to mitigate risk. For Lehman Brothers $150 billion total of debt, $400bn of CDS contracts were in issuance. The $60 trillion market for these weapons of mass destruction has taken gambling to a new and unprecedented level.