Market benchmark Sensex plunged nearly 400 points in opening session on Wednesday. Starting over 393.03 points lower, the Sensex pared some losses to trade 201.94 points, or 0.5% down in opening trade. The Nifty also dropped 58.10 points, to open trade at 11,739.80. Top losers in the Sensex pack included Sun Pharma, Bharti Airtel, Tata Steel, Reliance Industries and HDFC, shedding up to 2%. HUL, Nestle India, Power Grid and Asian Paints were among the gainers. The Rupee opened higher on Wednesday, at 71.75 against the US dollar.