The Sensex opened with a positive gap of 58 points at 13,107, and soon rallied to a high of 13,146, before slipping into the negative zone to a low of 12,957.The index has rebounded into the positive zone and and is now up 20 points at 13,069.Dr.Reddy's has slipped over 2% to Rs 662. BHEL, Reliance Communications and Grasim have dropped around 1.5% each to Rs 2,140, Rs 428 and Rs 2,202, respectively.Satyam, Larsen & Toubro and Tata Steel are down 1% each at Rs 441, Rs 1,505 and Rs 424, respectively. HDFC and ITC are the notable gainers at Rs 1,562 and Rs 161, respectively.