The Sensex at the Bombay Stock Exchange, that surged 481 points to regain the 16,000 mark in opening trade, was trading 451 points up at 16,243 in afternoon deals. All the sectoral indices were trading in the positive zone, with gains of up to 4.39 per cent on heavy buying by foreign funds. The Sensex had lost almost 905 points over the previous four sessions.In a similar fashion, the wide-based National Stock Exchange Nifty Index was trading 141 points up at 4,892 points.Meanwhile, in the Asian region, Hong Kong's Hang Seng Index rose by 2.01 per cent and Japan's Nikkei by 1.14 per cent in Friday trade. The Dow Jones Industrial Average ended 1.68 per cent higher in Thursday's trade.