The Bombay Stock Exchange benchmark Sensex rose by over 155 points in early trade today. The rise is on sustained buying of RIL, Infosys and Bharti Airtel stocks amid a firming trend in global markets. The Sensex was trading at 17,651, up by 180 points when reports last came in. Similarly, the wide-based National Stock Exchange index Nifty also opened in the positive territory and was trading 55 points up at 5296.Meanwhile, the Hong Kong Hang Seng Index and the Japan Nikkei index rose by 0.69 per cent in early trade today. The Dow Jones Industrial Average index rose 1.20 per cent in yesterday's trade.