The BSE benchmark Sensex regained psychological 20,000 mark by soaring 240 points in opening trade today as banking stocks led the rally after RBI reduced the marginal standing facility rate to improve liquidity in the system. The 30-share index gained 240 points to trade at 20,135 with all sectoral indices trading in the positive zone rising up to 3.59 per cent. The wide-based National Stock Exchange index Nifty rose by 63 points to trade at 5,970. In the Asian region, Hong Kong's Hang Seng index rose by0.34 per cent, while Japan's Nikkei was down marginally by 0.07 per cent in early trade. The US Dow Jones Industrial Average ended 0.90 per cent lower yesterday.