The Sensex at the Bombay Stock Exchange was trading 149 points in the negative territory at 18,625 in late morning deals, when reports last came in. The 30-share barometer, which had gained 55 points in the previous session, fell by 131 points in opening trade today.The Nifty at the National Stock Exchange was trading 58 points down at 5,610.In the Asian region, Hong Kong's Hang Seng index fell by 1.18 per cent, while Japan's Nikkei Index edged was up by 1.42 per cent in early trade.