CHICAGO – The lawsuit filed by the US Securities and Exchange Commission against Goldman Sachs for securities fraud, charging the bank with misrepresenting the way a collateralized debt obligations (CDO) had been formed, has revived public disgust at credit default swaps (CDS), the instrument used to bet against these CDOs. Before the 2008 financial crisis, CDSs were an esoteric product, known only to a restricted number of sophisticated investors and specialized academics.