The BSE benchmark index Sensex rose by another 105 points or 0.61 per cent to 17,424 points in early trade today. It extended gains for the fourth straight session, on sustained buying by funds and retail investors, amid encouraging fourth quarter corporate earnings and a firming trend in other Asian markets.The 30-share barometer had gained over 188 points in the previous three sessions.In a similar fashion, the wide-based National Stock Exchange index Nifty moved up by 30 points, or 0.58 per cent, to 5,278 points.In the Asian region, Hong Kong's Hang Seng Index rose by 1.06 per cent, while Japan's Nikkei index went up 0.50 per cent in morning trade today. The US Dow Jones Industrial Average ended 0.50 per cent higher in yesterday's trade.