The Sensex opened a tad lower (three points) at 10,863. The index tumbled to a low of 10,803, and then rebouned into the positive zone to touch a high of 10,870.The index, however, has slipped back into the negative zone and is now down 47 points at 10,817.BHEL has gained 1.5% at Rs 2,182. HLL, Ranbaxy, Cipla and Reliance Energy are the other notable gainers.HDFC Bank and Dr.Reddy's have slipped nearly 1% each to Rs 793 and Rs 1,415, respectively.SBI, Maruti, Wipro, Bajaj Auto, Gujarat Ambuja, Reliance Communications, Grasim and TCS are the other notable losers.