Jérôme Kerviel bank a profit of US$2 billion as of 2007. Managers for Société Générale have described some of the means Kerviel employed to avoid the bank's internal controls and escape detection. Its Executive Chairman Daniel Bouton describes the pattern as like "a mutating virus" in which hundreds of thousands of trades were hidden behind offsetting faked hedge trades. Officials say Kerviel was careful to close the trades in just two or three days, just before the trades' timed controls would trigger notice from the bank's internal control system, and Kerviel would then shift those older positions to newly initiated trades. City
Jérôme Kerviel experts have expressed skepticism of the bank's account, saying that a pattern of closing out trades within the three-day cycle alleged could not be accomplished given the immense sums involved. Kerviel is not thought to have profited personally from the suspicious trades. Prosecutors say Kerviel has been cooperative with the investigation, and has told them his actions were also practiced by other traders in the company. Kerviel admits to exceeding his credit limits, but claims he was working to increase bank profits. He told authorities that the bank was happy with his previous year's performance, and was expecting to be