The BSE benchmark Sensex was trading 10 points or 0.07 per cent down at 15,847 points in afternoon deals. The 30-share Sensex fell by 151 points in opening trade today as participants booked gains recorded in the previous session amid a weakening trend on other Asian bourses.The wide-based National Stock Exchange Nifty was also trading 2 points or 0.04 percent down at 4,754 points.