The BSE benchmark Sensex today shot up by over 165 points in early trade, extending gains for the fourth straight session, on continued buying by funds and retailers. The rise was driven by the government's bid to fast track the infrastructure projects and hopes of a rate cut by RBI. The 30-share index rose further by 165.24 points to 16,619.54 in early trade. Yesterday, it had recorded a hefty rise of 433.66 points, the highest single-day gain this year. Similarly, the wide-based National Stock Exchange Niftyindex regained the 5,000 mark to trade 45 points percent higher, at 5,042.30.