The BSE benchmark Sensex rose by over 72 points to 18,346 points in opening trade today on sustained buying by funds. The Sensex gained nearly 812 points in the previous three sessions. Similarly, the wide-based National Stock Exchange Nifty index gained over 10 points to 5,491 in opening trade today.Traders said, in addition to the strong corporate earnings posted by Tata Steel, continued short-covering by speculators also buoyed the sentiment, helping the Sensex maintain its upward journey. Meanwhile, Japan's Nikkei Index was up by 0.11 per cent and Hong Kong's Hang Seng Index down 0.12 per cent in early trade today. In the US, the Dow Jones Industrial Index ended 0.34 per cent lower yesterday.