The BSE benchmark Sensex fell by over 77 points in early trade today after three sessions of gains on emergence of profit-booking by funds and retailers amid a mixed trend in Asian markets.The 30-share barometer declined by 77.03 points, or 0.38 per cent, to 20,083.79 with banking, consumer durables and capital goods stocks leading the fall. The index had gained nearly 487 points in the last three sessions.In the Asian region, Hong Kong's Hang Seng index eased by 0.67 per cent, while Japan's Nikkei up 0.520 per cent in the opening trade today.The US Dow Jones had ended 0.69 per cent higher in yesterday's trade.