Equity benchmark Sensex tumbled over 300 points in early trade on Wednesday, tracking losses in index-heavyweights HDFC, Infosys and ICICI Bank amid a largely negative trend in global markets. The 30-share BSE index was trading 309.54 points or 0.60 per cent lower at 51,625.34 in initial deals, and the broader NSE Nifty fell 70.45 points or 0.45 per cent to 15,504.40.

Tech Mahindra was the top loser in the Sensex pack, shedding over 3 per cent, followed by ITC, HDFC, HCL Tech, Kotak Bank, Infosys and ICICI Bank. On the other hand, NTPC, PowerGrid, Sun Pharma, Maruti and Reliance Industries were among the gainers. In the previous session, Sensex ended 2.56 points lower at 51,934.88, while the broader NSE Nifty slipped 7.95 points or 0.05 per cent to 15,574.85.