The Bombay Stock Exchange benchmark Sensex fell by nearly 80 points in opening trade today due to profit booking by funds amid weak global cues. The 30-share barometer, which had gained 68 points in the previous session, fell to 18,966 points. The wide-based National Stock Exchange Nifty index also declined by over 24.30 points to 5,687 points. Japan’s Nikkei was trading 0.87 per cent lower, while Hong Kong’s Hang Seng index marginally up by 0.05 per cent in early trade. In the US, the Dow Jones Industrial Average ended 0.02 points lower yesterday.