Giving up all its initial gains, the Sensex at the Bombay Stock Exchange lost 96 points, or 0.5 per cent, to slip below the 20,000 mark, at 19,931 in afternoon deals, a short while ago. Earlier in the morning, however, the Sensex had opened with a gain of 46 points, or 0.2 per cent, at 20,072, on fresh buying by funds and retail investors. Stock markets in China, Hong Kong, Taiwan and South Korea had fallen between 0.1 percent and 0.9 percent, today. But the US Dow Jones Industrial Average had ended 0.5 per cent higher in yesterday's trade.