The Bombay Stock Exchange benchmark Sensex gained nearly 160 points in opening trade today. The gain in Sensex was due to better-than expected quarterly earnings by Hero Honda and other companies. The Sensex was trading at 18, 690, up by over 254 points a short while ago.In a similar fashion, the wide-based National Stock Exchange Nifty index was trading at 5616, up by 75 points.Meanwhile, in the Asian region, Japan's Nikkei Index was trading 0.86 per cent higher, while Hong Kong's Hang Seng Index rose by 1.25 per cent in early trade today. The US Dow Jones Industrial Average ended 1.21 per cent higher in yesterday's trade.