The U.S. dollar rallied and most of the stocks were down after the Fed's Chairman Ben Bernanke's semi-annual testimony. Soon after Bernanke announced that the Fed is ready to offer extra monetary aid to a slowing down U.S. economy, U.S. markets turned lower. The Dow Jones Index erased 0.61 per cent, to 12,650.17, the S&P 500 Index dropped 0.59 per cent, to 1,345.64 and The Nasdaq Composite Index tumbled 0.27 per cent, to 2,889.03. At the same time, the greenback strengthened 0.3 per cent against yen and 0.4 per cent versus single currency.