The Sensex rose 53 points to 21,343 points in early trade today on sustained buying by funds amid a firm trend on other Asian bourses. The Sensex had gained 257 points yesterday.The wide-based Nifty of the National Stock Exchange moved up 17 points to 6,338.In the Asian markets, Hong Kong's Hang Seng rose 0.80 per cent, while Japan's Nikkei went up 0.45 per cent in early trade today.The US Dow Jones Industrial Average gained 0.66 per cent to close at fresh record high yesterday.