The US Securities and Exchange Commission (SEC) is investigating shares sales made by Société Générale board member, Robert A. Day, who sold nearly €100 million worth of stock eight days before the bank’s €5 billion trading scandal emerged.

Both the SEC and the US Justice Department are examining the transactions made by Mr Day, according to The Wall Street Journal.

As well as sitting on Société Générale’s board, Mr Day is the founder of TCW, a Los Angeles investment group that is a subsidiary of Société Générale.

Documents released by the AMF, the French market regulator, show that Mr Day sold off €85.7 million in shares on January 10.

Also, two trusts connected to Mr Day, offloaded large chucks of shares on the same day - the Robert A. Day Foundation sold €8.6 million in stock and the Kelly Day Foundation sold €959,066.

Details of the US investigations emerged as France's Finance Minister, Christine Lagarde, published a report into the Société Générale scandal.

Jerome Kerviel, a 31 year-old trader made a series of large deals resulting in the unexpected loss and the possibility that Société Générale will now be taken over by a rival.

Société Générale discovered the irregular traders “several days” prior to January 18 when Mr Kerviel’s management was informed.

Commenting on the closure of the trading positions on the cusp of widespread turmoil across the world’s largest financial centres, Ms Lagarde’s investigation found “the unwinding of the operations in question are not the cause of the negative and volatile movement of the financial markets between January 21 and 23”.

The report, which was handed to French Prime Minister, Francois Fillon, also found flaws in Société Générale internal controls and called for tougher regulation of French banks’ risk controls and higher penalties for fraud.

Ms Lagarde said that “very clearly some internal control procedures didn’t work, and those that did weren’t always followed up with appropriate modifications”.

She added: “There is a risk which is operational risk, as opposed to market risk, which must be taken more seriously into consideration.”

Last week Société Générale said that the period during which Mr Day sold his shares "was a window of time were such trades were permitted under Société Générale's trading policies for directors".

Société Générale added: "No inside information was used in any way with respect to these December and January sales.

"In particular, before these trades were made, Mr Day, like the other board members, was not advised of Mr. Kerviel's trading losses. Neither was he advised, like the other non-executive board members, that additional subprime-related write-downs or reserves would be made.

"Such writedowns and reserves were presented to the board for the first time on January 20, 2008. Mr. Day has pledged his cooperation into any inquiries of this matter."

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