The Bombay Stocks Exchange benchmark Sensex which gained 206 points in opening trade lost its early gains and was trading at 16, 616, up by 165 points a short while ago. Brokers said rise in Sensex is on the back of funds buying propelled by hopes of better quarterly results and a firming trend on other Asian bourses.The wide-based Nifty of the National Stock Exchange regained the psychological 5,000 points mark rising by 57points 5,012.85, for the first time since December 8 last year. It was trading 54 points up at 5,010 a short while ago.In Asia, Hong Kong's Hang Seng Index rose by 0.75 per cent and Japan's Nikkei Index by 0.54 per cent in morning trade today.The US Dow Jones Industrial average ended 0.78 per cent higher in yesterday.