Back in early 2007, Fabrice Tourre was feeling pretty pleased with himself. Not only was the 28-year-old Frenchman working for Goldman Sachs in New York, he had become a high-flying specialist in the booming field of collateralised debt obligations, or CDOs – the complex business of chopping up multiple mortgage debts into investable securities.

Though Mr Tourre, a Goldman Sachs vice-president, had been concerned for some time about the failing health of the underlying market – the debt, or “l(fā)everage”, was overwhelming and poor people with big subprime mortgages were starting to default on their loans – his continued success in punting his CDOs to unconcerned investors was giving him a buzz. On January 23 2007, he e-mailed a friend, flush with the success of his latest deal, the Abacus 2007-AC1. “More and more leverage in the system,” he wrote. “The whole building is about to collapse anytime now . . . Only potential survivor the fabulous Fab[rice] . . . standing in the middle of all these complex, highly leveraged, exotic trades he created without necessarily understanding all of the implications of those monstruosities [sic]!!!”

By last Friday, “the fabulous Fab” was looking rather less heroic. In a 22-page complaint, the Securities and Exchange Commission, the US financial regulator, charged Mr Tourre and Goldman with securities fraud, accusing them of misleading investors, omitting crucial information and misrepresenting the product. The lawsuit charged the Goldman team with encouraging unwitting investors to buy a product conceived, at least in part, by a client (hedge fund Paulson & Co) that was busy betting against the very same underlying mortgage investments via credit default swap (CDS) insurance contracts.