The Sensex opened at 81,377.39 against its previous close of 81,635.91 and crashed nearly 700 points, or 1 per cent, to an intraday low of 80,947.26. The Nifty 50 opened at 24,899.50 against the previous close of 24,967.75 and dropped by almost 1 per cent to its day’s low of 24,755.60.