Bush's billionaire friend sold £100m of shares just days before scandal broke

A billionaire ally of President George Bush could face a criminal investigation into insider share dealing after selling £100million of shares just days before Societe Generale's rogue-trader losses were reported.

Robert Day, a member of the French bank's board, disposed of a million shares on January 9 and 10, plus a further 500,000 on January 18, according to official disclosures to Autorite des Marches Financiers (AMF), France's market regulator.

The £3.7billion losses at the bank were not disclosed to the public or investors until January 24, despite reports that Societe Generale bosses were aware of the crisis several days earlier.

The AMF is investigating after complaints by minority shareholders who claim some protected themselves at the cost of less influential investors. A source confirmed that Mr Day's share dealings are part of that investigation.

A file lodged with public prosecutor Francois Foulon also demands an inquiry into alleged insider trading and fraud.

The claims were submitted by Frederik-Karel Canoy, a lawyer acting for 100 shareholders, who alleges that Mr Day acted after consultations with "three or four" other key figures in the bank to discuss the looming crisis.

Their meetings were held at Paris restaurants rather than over the phone or by email, Mr Canoy claims.

But a spokesman for Mr Day, a major cash backer of Mr Bush who is now helping Mitt Romney's White House bid, said last night that it was coincidence that he unloaded the stock just before it plunged. "He received no inside information before the sales were made," he added.

He said Mr Day had no idea the bank was in trouble until a board meeting on January 20, two days after the last of his share sales.

He added: "Mr Day still holds 1.9million shares in Societe Generale."

He got the shares in 2001 when the bank bought US fund manager Trust Company of the West, which he had co-owned.