Sensex closed at 83,013.96, up 320.25 points or 0.39 per cent. The 30-share index opened with a decent gap-up at 83,108.92 against the last session's closing of 82,693.71 after the US Fed announced a rate cut. Nifty ended the session at 25,423.60, up 93.35 points or 0.37 per cent.