The Sensex at the Bombay Stock Exchange stood 156 points, or 0.8 percent in positive territory, at 20,187 in afternoon trade, amid volatility, a short while ago. Earlier in the morning, the Sensex had opened with a gain of 69 points, or 0.3 per cent, at 20,100, on sustained buying by funds and retail investors, amid firm regional bourses.The Sensex had advanced 356 points in the previous two trading sessions.Stock markets in Japan, China, Singapore, South Korea and Hong Kong had added between 0.2 percent and 1.4 percent, today.