Equity benchmark Sensex rallied over 500 points in early trade on Friday, tracking gains in index majors HDFC twins, ICICI Bank and L&T amid a positive trend in global markets.The 30-share BSE index was trading 500.92 points or 1.03 per cent higher at 48,941.04, and the broader NSE Nifty surged 156.30 points or 1.09 per cent to 14,481.20.