The Sensex in the Bombay Stock Exchange rose by nearly 90 points to 20,650 in the opening trade today, extending its four-session gaining streak on sustained buying by funds and retail investors. The stocks of consumer durables, oil and gas, and metal sectors are leading the rally.In a similar fashion, the National Stock Exchange Nifty index moved up by about 23 points to 6,181.05 points. Brokers said firming trend in Asia following overnight gains on the US market on encouraging manufacturing and constructions spending data buoyed the trading sentiments in Indian markets. They said expectations of strong earnings by corporate also generated buying activity.Meanwhile, the Hong Kong's Hang Seng index was up 0.23 per cent while the Japan's Nikkei gained 1.08 per cent in the morning trade. The US Dow Jones Industrial Average ended 0.81 per cent up in the previous session.