In the afternoon trading session on Wednesday, benchmark indices witnessed a sharp decline resulting from sudden selling in domestic markets. Sensex shed nearly 500 points from the day's high to close at 36,329.01 that is 345.51 points or 0.94 per cent lower than its previous close while Nifty fell by 93.90 points or by 0.87 per cent to close at the level of 10,705.75.