a structured instrument based on one or more underlying assets -- that is sold as a fund but trades like a stock. The ETF in question was one which tracked the volatile silver futures market and was priced in Swiss francs, they say. Adoboli's job would have been to hedge, or reduce, the bank's risk on the silver and franc positions by buying and selling each. It is thought that he may accidentally have left the Swiss franc vs U.S. dollar side of the equation uncovered and got stung when the Swiss national bank intervened to defend the franc in early September. Credit rating agency Moody's has said it is looking at UBS for a possible downgrade. Its review of UBS will focus on ongoing weaknesses in the group's risk management and controls as revealed by the reported loss, Moody's said in a statement. Moody's downgraded two French banks earlier this week amid questions over their exposure to debt. News of the alleged rogue trader comes amid pronounced economic anxiety in Europe. Markets there have been in turmoil in recent weeks as concern has mounted that Greece might default on its huge debt, sending shock waves through the 17-nation eurozone and further afield. Rogue trader's impact on UBS U.S. Treasury Secretary Timothy Geithner is attending a meeting of Europe's Economic and Financial Affairs Council in Wroclaw, Poland, on Friday, at which questions around Greek debt and