Bears tightened their grip on Dalal Street on Friday. Selling in blue-chip stocks hit the market for the second day in a row as traders liquidated positions in the derivatives segment. The 30-share BSE Sensex plunged 83.33 points to settle at 4,865.83. The S&P CNX Nifty also lost 31.50 points to 1,548.45. While there was some amount of selling from local funds, operators were major sellers as exposure norms were tightened. “The NSE imposed additional margins on brokers holding huge positions in derivatives. Rumours that additional margins would be payable in cash — and not shares — provided further impetus to the selling,” said a dealer. With Friday’s fall, Sensex has lost 140 points in just two trading sessions. Sensex had crossed the 5,000 mark last following heavy FII inflows. Foreign fund inflows have declined to the Rs 56-233 crore level recently, compared to the Rs 300-500 crore levels witnessed earlier.