In choppy trade, the Bombay Stock Exchange benchmark Sensex on Monday ended over 27 points lower on profit-booking at higher levels amid reports of a weakening global trend. In a volatile session, the Sensex opened 100 points down, before surging to a high of 18,005 during intra-day trade. However, it failed to hold on to the gains and fell again to close at 17,928.Meanwhile, the broad-based National Stock Exchange index Nifty surrendered 7.45 points to 5,386. During the session, it moved between 5,409. and 5,361 points.