A benchmark index of Indian equities markets Monday plunged 278.41 points or 0.97 percent up as banking stocks tanked.Almost all the sectors were trading in red. Heavy selling pressure was seen in the banking, auto, capital goods and metal sectors.The 30-scrip Sensitive Index (Sensex) of the S&P Bombay Stock Exchange (BSE), which opened at 28,566.50 points, was trading at 28,439.50 points (at 09.15 a.m.) in the early session, down 278.41 points or 0.97 percent from the previous day's close at 28,717.91 points.The Sensex touched a high of 28,566.50 points and a low of 28,439.50 points in the trade so far.The S&P bankex plunged by 127.47 points, auto index went down by 117.73 points, capital goods index fell by 94.95 points and metal index slipped by 86.82 points.The wider 50-scrip Nifty of the National Stock Exchange (NSE) was also trading 65 points or 0.75 percent down at 8,596.05 points.