Equity indices plunged on Monday with the benchmark BSE sensex falling nearly 1,750 points amid heavy sell off across sectors. After plunging to day’s low of 56,296, the 30-share BSE index finished 1,747 points or 3 per cent lower at 56,406; while the broader NSE Nifty settled 532 points or 3.06 per cent lower at 16,843.