BSE benchmark Sensex rose by 77 points in the opening trade today on sustained buying by funds. This follows cues from other Asian markets.The 30-share index of the Bombay Stock Exchange rose to 20.137.39 points in opening trade. The Sensex has gained over 410 points in the previous three sessions. Similarly, wide-based National Stock Exchange Nifty index moved up by 18.40 points to 6,019. Hong Kong's Hang Seng Index was up by 0.17 percent in early trade today, but Japan's Nikkei Index was down by 0.21 per cent. In the US, the Dow Jones Industrial Index ended 0.48 per cent higher yesterday.