Sensex closed at 80,723, while the Nifty settled at 24,825, losing 495 points or nearly 2 per cent. Markets were far weaker during the day, with the Sensex plunging almost 3,000 points at one stage to hit an intra-day low of 79,899.42. The Nifty also slipped sharply to a low of 24,572 before recovering slightly.