The Sensex opened with a positive gap of 47 points at 8,280, which turned out to to be the low for the day. Sustained buying saw the index zoom to a high of 8,487 - a gain of 264 points from the last weekend close. The Sensex finally closed with a gain of 256 points (3.12%) at 8,479.Reliance vaulted 4.3% (Rs 32) to Rs 780. ONGC zoomed over 3% (Rs 30) to Rs 1,020. SBI gained 3% (Rs 25) to Rs 915. HLL added 3.7% (Rs 6) to Rs 176, and ITC was up Rs 5 at Rs 143.Wipro advanced 5% (Rs 17) to Rs 374. Infosys gained over 3% (Rs 84) to Rs 2,484. TCS was up 4% (Rs 55) at Rs 1,466, and Satyam added 4% (Rs 22) to Rs 543.Gujarat Ambuja zoomed over 5% (Rs 4) to Rs 73. ACC gained nearly 3% (Rs 14) to Rs 477. Grasim was up 1.4% (Rs 19) to Rs 1,358. Maruti gained 4% (Rs 23) to Rs 573. Bajaj, Hero Honda and Tata Motors also finished with gains.BHEL moved up 4% (Rs 44) to Rs 1,145. HDFC added 3.5% (Rs 34) to Rs 990. L&T was up 3.7% (Rs 50) to Rs 1,422. Tata Steel added over 3% (Rs 13) to Rs 416. Bharti advanced nearly 3% (Rs 11) to Rs 350.