The Sensex is now down 720 points at 16,745.The NSE Nifty is down 223 points at 4,897.Reliance Energy has tumbled nearly 11% to Rs 1,750. HDFC has slumped 6.5% to Rs 2,615.Reliance Communications, ICICI Bank and SBI have plunged nearly 6% each to Rs 608, Rs 1,004 and Rs 2,067, respectively.Reliance, Larsen & Toubro and SBI have shed around 5% each at Rs 2,294, Rs 3,348 and Rs 193, respectively.ONGC has shed 4.5% at Rs 952. Mahindra & Mahindra has slipped over 4% to Rs 618.Satyam has surged 3.5% to Rs 424. TCS has advanced 2.6% to Rs 923, and Infosys has added 2% to Rs 1,584.The market breadth is extremely negative - out of 2,560 stocks traded so far, 2,288 have declined, 243 have advanced and 29 are unchanged.