Sensex dropped 693.86 points to end at 81,306.85, while Nifty declined 213.65 points, or -0.85%, to close at 24,870.10. Mahindra & Mahindra, Maruti Suzuki India and Bharat Electronics emerged as top gainers, while Asian Paints, UltraTech Cement and Tata Steel were among the losers. The benchmark index snapped a six-session winning streak during the last trading day for the week.