The Financial Services Authority (FSA) has banned Alexis Stensfors, a former proprietary trader at the Merrill Lynch International Bank in London, from working in the industry for at least five years because his actions "fell short" of industry standards.

Stensfors, who is Swedish, mispriced trades in an attempt to cover up some of the £300m of losses he had accumulated.

The senior trader deliberately overvalued short-term interest rate positions he traded on behalf of Merrill Lynch by about $100m in from mid-January to mid-February 2009 to reduce his losses. This forced the bank to make a $456mn write-down.

Stensfors was sacked from his job last June. Merrill Lynch was fined about £2.5mn in October for poor supervision.

According to the watchdog, Stensfors was banned because he showed lack of integrity and was not fit to perform any regulated activity.

"His conduct was deliberate, frequent and repeated over a one month period. He betrayed the trust placed in him by the firm," it said.

FSA added that Stenfors had cooperated fully and agreed to settle at an early stage in the investigation. This was his first offence and he did not personally profit from the act.