The benchmark Sensex today jumped 340 points, extending gains for the fourth straight session. The Bombay Stock Exchange barometer closed higher by340.44 points, or 2.11 per cent, at 16,498 points. The wide-based National Stock Exchange index Nifty spurted by 102 points to close at 4,898 points. Brokers said markets posted smart gains , on a flurry of buying by funds and retail investors, sparked by the government's move to push financial reforms. Prime Minister Manmohan Singh, yesterday, said the government would steadily pursue reforms to feed economic growth, while withdrawing the fiscal stimulus by next year.