The 30-share Sensex after opening a shade higher at 27,473.36 and advanced to a high of 27,501.15. However, it succumbed to selling pressure and dipped below the 27,000-mark with blue-chip stocks ICICI Bank, ONGC, Cipla and ITC, among other plummeting. It touched a low of 26,677.64 before settling 722.77 points or 2.63 per cent lower at 26,717.37, the lowest in nearly 5 months. This is the biggest single day fall in last four months after 855 points plunge on January 6. Besides, this is the second-biggest since Modi government took over on May 26, 2014. The 50-share NSE Nifty crashed by 227.80 points or 2.74 per cent to close below 8,100-mark at 8,097.