French bank Société Générale said today it has uncovered a US$7.14 billion fraud by a single futures trader.

France’s second-largest bank by market value said it would be forced to seek US$8.02 billion in new capital.

The bank said it detected the fraud at its French markets division the weekend of Jan. 19-20. In a statement announcing the discovery, it called the fraud “exceptional in its size and nature.”

It said a trader at the futures desk had misled investors in 2007 and 2008 through a “scheme of elaborate fictitious transactions.”

The trader, who was not named, used his knowledge of the group’s security systems to conceal his fraudulent positions, a statement from the bank said.

The individual confessed to the fraud, the bank said, and was being dismissed. His supervisors were to leave the group. Chief executive Daniel Bouton offered his resignation, but the board rejected it.

An analysis confirmed the “isolated and exceptional nature” of the fraud, the bank said.

The fraud announcement came on the back of subprime-related difficulties. Subprime writedowns linked to the crisis in financial markets amounted to US$2.99 billion, Société Générale said.

Despite the writedown and losses, the company will post a net profit of US$874 million to US$1.16 billion for all of 2007, the Paris-based bank said.

Trading in Société Générale’s shares was suspended on the Paris bourse. It was unclear when trading would resume.