The BSE benchmark Sensex fell sharplyby over 252 points in the opening trade today .The 30-share barometer, which gained nearly 112 points in the previous sessions, fell by 252.07 points, or 1.54 per cent, to 16,076.18.Similarly, the wide-based National Stock Exchange Nifty index slid by 75.05 points, or 1.51 per cent, to 4,867.75 points.