The Sensex is now down 683 points at 17,315.Reliance Energy has slumped 15% to Rs 1,354. Maruti has plunged 8.6% to Rs 1,050.BHEL, HDFC and Bharti Airtel have tumbled around 7% each to Rs 2,024, Rs 2,275 and Rs 949, respectively.ACC has dropped 5.3% to Rs 981, and Mahindra & Mahindra has shed 4.5% to Rs 728.Reliance, ICICI Bank, Larsen & Toubro and Hindalco have declined 4% each to Rs 2,470, Rs 997, Rs 3,025 and Rs 180, respectively.Infosys, the only gainer among the index stocks, is up 1.3% at Rs 1,913.Out of 2,636 stocks traded so far, 2,149 have declined, 438 have advanced and 49 are unchanged.