The BSE benchmark Sensex tumbled by 193 points to 16,120 due to persistent selling pressure mainly from auto, refinery, banking, consumer durables and IT sectors, triggered by fall in rupee value against the dollar. The Sensex resumed lower at 16,225 points anddropped further.The NSE 50-share Nifty also declined by 53.95 points, or1.09 per cent, to 4,897.