After opening with a negative gap of 171 points at 20,080, the Sensex soon broke the 20,000-mark and slipped to a low of 19,795/. The index is now down 341 points at 19,910.The NSE Nifty has also drifted below the 6,000-mark and is now down 118 points at 5,956.Reliance Communications has tumbled nearly 5% to Rs 740, and HDFC Bank has slumped 4.7% to Rs 1,702.Reliance Energy and DLF have plunged over 4% each to Rs 2,263 and Rs 1,127, respectively.Tata Motors, Maruti and Reliance have slipped over 3% each to Rs 744, Rs 839 and Rs 3,066, respectively.Hindalco and Bharti Airtel have shed 2.8% each at Rs 192 and Rs 834, respectively.NTPC, Mahindra & Mahindra and BHEL have declined around 2.5% each to Rs 267, Rs 718 and Rs 2,360, respectively.ICICI Bank and Tata Steel are down nearly 2% each at Rs 1,326 and Rs 837, respectively.TCS, however, has gained 2% at Rs 957.