The City watchdog has banned a former senior trader at Merrill Lynch in London after he inflated the value of his trading book by more than $100m (£66m) to cover up huge losses.
The Financial Services Authority (FSA) announced Alexis Stenfors was "not a fit and proper person" to work in financial operations in the City and banned him for five years.
Managers at Merrill Lynch International Bank (MLIB) started asking questions about the value of the book run by Mr Stenfors, a short-term interest-rate trader, last February while he was on holiday. When he returned, he admitted "mismarking" his trading positions during the previous month.
He increased the value of his positions to hide increased losses when the market moved against him during a period of huge volatility in the markets. This caused the financial services group, now Bank of America Merrill Lynch, to write down its books by $456m (£299m) after the manipulation had been discovered.
Margaret Cole, the FSA's director of enforcement and financial crime, said: "Stenfors' actions in deliberately mismarking his positions fell far short of the FSA's expectations. Market confidence is likely to be damaged by sudden and unexpected write-downs and revaluations of securities."
She added that the regulator had banned Mr Stenfors "because his misconduct was deliberate, frequent and repeated over a one-month period. He was a senior and experienced trader who held a position of trust at the firm." The FSA capped the ban at five years because Mr Stenfors "expressed remorse for his actions and agreed to settle at an early stage".
MLIB was under the jurisdiction of the Irish Financial Regulator, which fined the business €2.7m (£2.4m) in October for failures relating to the case. The FSA's inquiry did not include the bank, but covered Mr Stenfors because he was licensed with the UK regulator. Merrill Lynch dismissed him in June.
In February, the FSA banned hedge-fund manager Simon Treacher for mismarking funds which lost investors about $650,000 (£427,000).