According to AMF, the trader was found to have used insider data to inform the sale of shares from Societe Generale in August 2007.
The sale was made before the start of the subprime mortgage crisis, which pre-empted the global financial crash.
Mr Mustier, who resigned from his position with the bank in August 2009, is expected to file an appeal against the ruling by the AMF.
The AMF said in a statement, which was quoted by Reuters, that âthe level of Mr Jean-Pierre Mustierâs responsibilities imposed on himâ a duty to not to sell the shares when he did.
Mr Mustier was in charge of Societe Generaleâs investment banking unit during the period when Jerome Kerviel worked with the firm.
The latter was recently tried over charges of forgery and breach of trust in relation to the loss of â¬4.9 billion during trading in 2008.
The verdict of the trial, which finished last week, is due to be given in October.
By Jim Ottewill