Equity benchmark Sensex tumbled 336.46 points on Thursday following losses in index heavyweights Reliance Industries, Infosys and TCS amid a negative trend in global markets. The 30-share BSE index declined 336.46 points or 0.55 per cent to 60,923.50. Similarly, the NSE Nifty fell 88.50 points or 0.48 per cent to 18,178.10. Asian Paints was the top loser in the Sensex pack, tanking around 5 per cent, followed by Reliance Industries, Infosys, Tata Steel, TCS and Dr Reddy’s.