The BSE benchmark Sensex fell by over 221 points in opening trade today.The 30-share Sensex, which lost 57.60 points in the previous session, fell by 221.31 points, or 1.30 per cent, to 16,803.78 in opening trade.In a similar fashion, the wide-based National Stock Exchange Nifty index declined by 67.70 points, or 1.32 per cent, to 5,050.55.