Credit Agricole reported on Thursday a net loss of 1.47 billion euros ($1.95 billion) last year owing to the Greek debt crisis, costs of a restructuring plan and asset write-down charges.
The bank did not give an outlook for 2012, but said that it would not pay shareholders a dividend for 2011.
In 2010, the bank, France's third-biggest by market capitalisation, had posted a net profit of 1.26 billion euros.
The latest result missed an average analyst forecast gathered by AFP of a more modest loss of 856 million euros.
In the fourth quarter of 2011, Credit Agricole reported a loss of 3.1 billion euros, worse than the comparable loss of 328 million euros 12 months earlier.
A bank statement said the group had been hit by the costs of absorbing problems associated with Greece, estimated at almost 2.4 billion euros, an adjustment plan which took effect late last year and impairment charges first announced on December 14.
It has launched a plan to cut debt by 50 billion euros from June 2011 to December 2012, and said that by the end of last December it had cut refinancing needs by 21 billion euros.