A banker in Pakistan has been charged with conspiracy and securities fraud by the US District Court in Manhattan.
It is alleged Mr Rahim knew in advance about the sale of TXU Corp
Federal prosecutors allege Ajaz Rahim made $7.5m (£3.8m) through insider trading, most of it from knowledge about the sale of energy firm TXU Corp.
They say that Mr Rahim received the information from a Credit Suisse banker who was charged earlier this month.
An arrest warrant has been issued for Mr Rahim but his lawyer said his client would contest all the charges.
But Spencer Barasch added that he did not know where Mr Rahim was at the moment or whether he would turn himself in.
Mr Rahim was country head of investment banking at Faysal Bank in Karachi.
Prosecutors say that he was given information by Hafiz Muhammed Zubair Naseem, who worked for Credit Suisse in New York and had previously worked with Mr Rahim at American Express Bank in Karachi.
The FBI said Mr Naseem had "regularly and repeatedly" called Mr Rahim between April 2006 and February 2007 and provided him with secret information.
The Securities and Exchange Commission (SEC) earlier filed civil charges against Mr Rahim.
Mr Naseem has been freed on $1m bail.