The Bombay Stock Exchange benchmark Sensex today opened 86 points higher on buying by foreign funds driven by firming global trends.The sensex was trading at 18103, up by 22 points when reports last came in. Similarly, the wide-based National Stock Exchange index Nifty 5,438 points, up by 6 points. The Hong Kong's Hang Seng index was up by 0.73 per cent, while Japan's Nikkei gained 1.53 per cent. The US Dow Jones Industrial Average ended 1.99 per cent higher in yesterday's trade.