The Sensex has made a strong opening, with steep surge in tech, select banking, cement and auto economy counters driving the index past the 6,400 mark. After resuming four points higher at 6,392 and touching an early high of 6,424, the Sensex is now up 35 pts at 6,423. The Nifty, too, has firmed up in early trades with gains of nine points over its last close at 1,986.Infosys has advanced 2% (Rs 40) to Rs 2,062. While Satyam has gained 1.92% (Rs 8) to Rs 421, Wipro is up 1.26% (Rs 8) at Rs 645.ICICI Bank is up a per cent (Rs 3) at Rs 379. While SBI is up RS 3 at at Rs 620, HDFC Bank is down a rupee at Rs 540.ITC and HLL are up a rupee each at Rs 1,442 and Rs 135, respectively. Reliance, however, is marginally down at Rs 548.ACC has firmed up 1.83% (Rs 7) to Rs 384. While Gujarat Ambuja is up a per cent (Rs 4) at Rs 434, Grasim is marginally down at Rs 1,149.Maruti (up Rs 6 to Rs 439), Hero Honda (up Rs 3 to Rs 543) and Tata Motors (up Rs 4 to Rs 430) have resumed in the green. Bajaj has slipped a per cent (Rs 7) to Rs 1,107.Dr. Reddy's has crashed 5.43% (Rs 36) to Rs 630, while Cipla is up a per cent (Rs 3) at Rs 274. Ranbaxy, too, has commenced with a per cent gain (Rs 5) at Rs 962.