Britain's FTSE 100 fell back on Friday as hopes faded that Federal Reserve Chairman Ben Bernanke would support a struggling U.S. economy with more quantitative easing measures, according to Reuters. Banks were the main drag on the FTSE 100 as the Bernanke expectations dwindled, with the FTSE banks index down 1.5 percent. The index has lost 61.7 percent since late July as worries have grown about contagion from the euro zone debt crisis and a slowing economic environment. Investors had hoped Bernanke, who is due speak at a Fed conference in Jackson Hole, Wyoming, at 1400 GMT, would signal further quantitative easing measures. Although he may acknowledge that the U.S. economy is showing signs of weakness, it is unlikely that Bernanke will announce QE3, but rather signal smaller stimulus measures to help prop up the recovery. "Investors are flattening positions out ahead of the UK bank holiday weekend," said Rupert Armitage, director at Shore Capital. "The majority of what Bernanke says will come out after the close and no one wants to be exposed." The UK benchmark index FTSE 100 index was down 24.11 points, or 0.5 percent to 5,107.53, adding to the 1.4 percent loss in the previous session, when investors started to take profits ahead of the Jackson Hole conference. "There had been hopes earlier in the week and now the market is becoming concerned that we are not likely to see a major development," Keith Bowman, equity analyst at Hargreaves Lansdown Stockbrokers, said. The blue chip index has lost 16.1 percent since the July-August sell-off began, spooked by concerns about debt levels in the United States and the euro zone and slowing global growth. But it was holding above the 23.6 percent Fibonacci retracement level or 5,096.17 from its July-August sell-off, after briefly dipping below it, with the next resistance level seen at 5,284.96 or the 38.2 percent Fibonacci retracement. U.S. GDP figures due out at 1230 GMT will be the next clue to the state of the U.S. economy. AMEC FALLS A weaker growth environment weighed on AMEC which dropped straight to the bottom of the blue chip index, down 5.1 percent, after Societe Generale downgraded the oil services engineer to "hold" from "buy" to take into account a slowdown. Resolution was also among the FTSE 100's weakest performers, falling 1.6 percent after Deutsche Bank downgraded the closed book life insurer to "hold" from "buy". But Admiral bucked the trend and gained 2.9 percent, pushing it to the top of the blue chip index after Deutsche Bank upgraded the motor insurer to "buy" from "hold". 3I Group was also in the top performers list, up 1 percent in volumes 85 percent of its 90-day daily average after the Daily Express said American buyout firm KKR could acquire the private equity firm at 300 pence a share.