Sensex and Nifty opened with their biggest gap-ups in points term in four years on Monday, NDTV Profit reported. While Sensex rose 2,621.98 points to open above 76,500, Nifty opened over 807 points higher at 23,337.90 after multiple exit polls predicted PM Narendra Modi's return to power for a third consecutive term. All Nifty 50 stocks opened in green.