The BSE benchmark Sensex gained for the third straight session by adding another 44 points in early trade, on sustained buying by funds and retail investors. The 30-share index, which had gained over 208 points in the past two sessions, added another 44.30 points to 17,875.05.The wide-based National Stock Exchange index Nifty moved up by 11.80 points to 5,424.15.In Asia, Japan's Nikkei gained 0.09 per cent in morning trade today.