The BSE benchmark Sensex rose by 326 points in the noon trading.The 30-share index, which has gained 191 points in the early trade, rose further nearly by 135 points, to gain 326 points or 2.10 per cent, to trade at 15,900.The National Stock Exchange Nifty moved up by 101 points, or 2.18 per cent, to 4,737.