The Bombay Stock Exchange benchmark Sensex fell by 66 points in opening trade today, extending its losses for the third straight day on continued selling by funds, tracking a weak trend in the Asian region. The 30-share Sensex, which lost over 546 points in the previous two sessions, moved down further by 66 points, or 0.41 per cent, to 16,085 in opening trade. In a similar fashion, the wide-based National Stock Exchange Nifty index shed another 16 points, or 0.33 per cent, to 4,833. In the Asian region, Japan's Nikkei Index was trading 1.95 per cent down, while Hong Kong's Hang Seng shed 1.49 per cent in early trade. In the US, the Dow Jones Industrial Average down by 2.36 per cent in the previous session.