The Sensex opened almost flat at 13,110 - up eight points, but soon soon slipped into the negative territory and is now down 177 points at 12,925.
Tata Motors has slumped nearly 4% to Rs 359, and DLF has plunged 3.6% to Rs 356. Maruti has tumbled 3.4% to Rs 658.
Satyam, SBI and Sterlite have dropped nearly 3% each to Rs 313, Rs 1,393 and Rs 435, respectively.
ICICI Bank, Reliance Communications, Bharti Airtel, Infosys and TCS have slipped around 2% each to Rs 549, Rs 340, Rs 760, Rs 1,417 and Rs 663, respectively.
Ranbaxy, Tata Steel, HDFC, HDFC Bank and Wipro are down over 1% each at Rs 269, Rs 456, Rs 2,065, Rs 1,233 and Rs 341, respectively.