A benchmark index of Indian equities markets, the 30-scrip Sensitive Index (Sensex), on Monday plunged 271.88 points or 0.97 percent during the morning session.The wider 50-scrip Nifty of the National Stock Exchange (NSE) also plummeted 70.80 points or 0.83 percent and was trading at 8,447.75 points.The Sensex of the S&P Bombay Stock Exchange (BSE), which opened at 28,093.54 points, was trading at 27,795.43 points (at 9.23 a.m.) in the early session, down 271.88 points or 0.97 percent from the previous day's close at 28,067.31 points.The Sensex touched a high of 28,095.97 points and a low of 27,769.76 points in the trade so far.