Société Générale slumped to a surprise loss in the first quarter as higher than expected writedowns and provisions hit the bank's earnings.
SocGen, which fell victim to a rogue trading scandal last year, reported a net loss of €278m from a profit of €1.1 billion a year ago. Analysts had on average expected a first-quarter net profit of €320m.
Non-recurring items had a negative impact of €1.9 billion on its earnings, SocGen said. This reflected the impact of writedowns at its investment banking unit.
The bank's loss was in stark contrast to BNP Paribas, France's biggest bank by market capitalisation, which this week reported better-than-expected first-quarter profits.
Earlier this week SocGen said its CEO Frederic Oudea would also become chairman after Daniel Bouton, the previous chairman, resigned following a wave of negative publicity over the bank.
Bouton came under pressure after a rogue trading scandal in January 2008, when SocGen unveiled €4.9 billion of losses from unauthorised trades conducted by Jerome Kerviel, a former junior trader at the bank.
French President Nicolas Sarkozy criticised Bouton over the Kerviel affair and Sarkozy's administration again attacked the bank last month over executive pay packages.
SocGen's top managers were forced to give up stock options in March following public anger over the fact that money received from the French state to help it through the financial crisis could be used to remunerate executives.
SocGen added it could not rule out further writedowns in the future and said the economic outlook remained uncertain.
