Alexis Stenfors, a former Merrill Lynch trader has been banned by the FSA after hiding £67 million of trading losses by mis-marking positions.
His actions forced Merrill Lynch to lose over £304 million, the FSA said.
"He was a senior and experienced trader who held a position of trust at the firm" said the FSA, "He betrayed the trust placed in him by the firm and demonstrated that he is not fit and proper to be approved by the FSA".
Mr Stenfors is now barred from having any job within the regulated financial industry.
The mis-marking occurred between mid-January to mid-February 2009.