Indian benchmarks opened lower as Sensex slides 536 points on oil, geopolitics; Kotak, Sun Pharma, Adani Ports rise amid Fed meet anticipation. Sensex fell 609 points to 72,514 in early deals today. Nifty too slipped 133 points to 22,466 from the previous close of 22,600. Sensex rebounds about 483 points after four-day slump; Nifty edges higher as metal, telecoms, and healthcare rally.