The Bombay Stock Exchange benchmark Sensex fell by nearly 77 points in the opening trade today. This follows profit-booking by funds amid a weak trend in the Asian region.The 30-share barometer, which had gained over 550 points in last three session, fell to 19,722.39 points in first five minutes of trading.Similarly, the wide-based National Stock Exchange Nifty Index also declined by 26.35 points to trade at 5,917.75 points.Besides, other Asian markets were also in red. Hong Kong's Hang Seng index was 0.60 per cent down, while Japan's Nikkei was trading 0.04 per cent low in the early trade today.In the US, the Dow Jones Industrial Average ended 0.42 points higher in yesterday's trade.