The BSE benchmark Sensex fell by nearly 90 points in opening trade today. The 30-share barometer, which lost 220.26 points in the previous session on Friday, slid further by 89.57 points, or 0.47 per cent, to 18,768.47. In a similar fashion, the wide-based National Stock Exchange Nifty index shed 29.85 points, or 0.53 per cent, to 5,630.80 in morning trade today.