The Sensex, which advanced above the 6,400-mark in early trades, has registered further gains in current trades as strong buying continues in tech, auto and other select old economy stocks. The Sensex, after touching a high of 6,448 (up 60 pts over its last close), is now up 55 points at 6,443. The Nifty, too, has scaled up 15 points to 1,992.Infosys has flared up 3.64% (Rs 74) to Rs 2,095, while Satyam has jumped 2.53% (Rs 10) to Rs 424. Wipro is trading with steady gains at Rs 645 - up Rs 8 or 1.33%.ITC has added 1.19% (Rs 17) to Rs 1,458, and ONGC has clocked a per cent gain (Rs 8) to Rs 870. While Reliance is trading weaker by Rs 2 at Rs 547, HLL is marginally down at Rs 134.Maruti and Tata Motors have moved up nearly 2% each to Rs 442 (up Rs 9) and Rs 434 (up Rs 8), respectively. While Hero Honda is up a per cent (Rs 5) at Rs 545, Bajaj is trading a tad higher at Rs 1,114.L&T has gained a per cent (Rs 10) to Rs 1,020. While Tata Power has added 1.74% (Rs 6) to Rs 363, Tisco is up 1.48% (Rs 5) at Rs 359. HPCL, however, has lost 1.78% (Rs 6) to Rs 328.SBI is up a per cent (Rs 5) at Rs 622, and ICICI Bank is up a rupee at Rs 377. HDFC Bank, however, has edged lower by 1.33% (Rs 7) to Rs 534.ACC is up 1.13% (Rs 4) at Rs 381, and Gujarat Ambuja is up a per cent (Rs 4) at Rs 434. Grasim, however, is still marginally down at Rs 1,149.Dr. Reddy's, which dropped 5% in early trades, is trading lower by 2.89% (Rs 19) at Rs 647, while Cipla is up 1.45% (Rs 4) at Rs 276.