At the stock markets, after a firm opening, the Sensex at the Bombay Stock Exchange suddenly gained some momentum in afternoon trade, and had jumped 156 points, or 0.5 percent, to 31,990 a short while ago. The Nifty at the National Stock Exchange had climbed 50 points, to 10,035. And at the forex market, the rupee had appreciated 5paise, to 65.09 against the dollar in afternoon deals. Earlier, the benchmark Sensex rose by 112 points to 31,946 in early trade today.