A benchmark index of Indian equities markets, the 30-scrip BSE Sensitive Index (Sensex) tanked 217.49 points or 0.78 percent in the noon session on Monday.The wider 50-scrip Nifty of the National Stock Exchange (NSE) was also trading 61.70 points or 0.73 percent down at 8,397.25 points.The Sensex of the S&P Bombay Stock Exchange (BSE), which opened at 27,893.25 points, was trading at 27,740.01 points (at 12.52 p.m.) down 217.49 points or 0.78 percent from the previous day's close at 27,957.50 points.The Sensex has touched a high of 27,903.29 points and a low of 27,713.32 points in the intra-day trade so far.Healthy buying was observed in oil and gas sector, while selling pressure was seen in fast moving consumer goods (FMCG), metal and capital goods sectors.The S&P BSE oil and gas index gained by 0.30 percent, while FMCG index dropped by 1.39 percent, metal index fell by 1.33 percent and capital goods index went down by 0.78 percent.