The Sensex has dipped sharply in the last few minutes of trades and is now down 840 points at 19,190.NTPC has slumped 8% to Rs 227. DLF and ONGC have plunged 7% each to Rs 949 and Rs 1,152, respectively.Tata Steel has tumbled 6.5% to Rs 821. HDFC has dropped over 6% to Rs 2,870. Reliance Communications and Hindalco have slipped 5.7% each to Rs 716 and Rs 201, respectively.Tata Motors, BHEL and Bharti Airtel are down nearly 5% each to Rs 708, Rs 2,437 and Rs 907, respectively.Out of 2,940 stocks traded so far, 1,678 have declined, 1,242 have advanced, and 20 are unchanged.