The Bombay Stock Exchange benchmark Sensex on Monday jumped by 236 points, in opening trade on fresh buying in heavyweight stocks by foreign funds.The 30-share index rose by 236.28 points to 17,776.57 points. The BSE barometer had lost over 160 points in the past two sessions.The wide-based National Stock Exchange index Nifty rose by 42.45 points, to 5,287.20 points.The Sensex was up by 66 at 17606 when news last came in. AT the same time Nifty was up by 5266 at 21.