Jérôme Kerviel caused Société Générale to lose about €4.9 billion through unauthorized trades in 2008.
Kerviel was a junior trader on the bank’s Delta One desk in Paris. He built enormous positions in European stock-index futures, initially attempting to profit from market movements. To conceal the size of those positions, he used fictitious trades and manipulated the bank’s control systems.
Société Générale discovered the positions in January 2008 and closed them during a turbulent market. The unwinding produced one of the largest trading losses ever attributed to a single employee. The bank announced the loss at roughly €4.9 billion, while also reporting that Kerviel had exceeded trading limits.
Kerviel’s case is often compared with Nick Leeson’s collapse of Barings Bank, but the scandals involved different banks and trading strategies. French courts convicted Kerviel of abuse of confidence and related offenses; later legal proceedings changed the financial damages imposed on him.