Laurent Mignon, chief executive of Natixis, said the guarantee would cost Natixis a premium of about ?48m a year over 10 years.
Natixis posted a net loss of ?883m for the second quarter, marking its fifth consecutive quarter in the red, with results weighed down by writedowns and bad debt charges. The bank made an additional provision of ?748m related to risky property assets and leveraged buy-outs (LBOs).
But the overall net loss was a considerable improvement on its ?1,839m net loss in the first quarter, and was less than some analysts had predicted.
François Pérol, chairman of Natixis and a former financial aide to Nicolas Sarkozy said in a conference call that the bank could return to profit in the third quarter. He said that BPCE would have no need for additional funds from the government, and could start reimbursing the state at the end of 2010. BPCE, formed from the merger of Natixis?? two largest shareholders earlier this year, has so far received about ?7bn from the state, most of which it channelled into Natixis.
Shares in Natixis soared over thirty per cent on Wednesday morning after they have been suspended from trading on Tuesday.