The BSE benchmark Sensex today breached the 20,000-mark in opening trade after two years. It gained over 100 points in early trade to touch a little higher than 20,000.Similarly, the wide-based National Stock Exchange index Nifty inched up by 3.35 points, or 0.06 per cent, to 6,027.40.Meanwhile in the Asian region, Hong Kong's Hang Seng shed 0.26 per cent, while Japan's Nikkei was up 1.26 per cent in early trade today. The US Dow Jones Industrial Average ended 0.14 per cent higher in yesterday's trade.