Equity indices plunged on Friday with the benchmark BSE Sensex falling over 500 points, dragged by financial, banking and IT stocks amid weak global cues. The 30-share BSE index fell 536 points or 1.68% to close at 31,327; while the broader NSE Nifty dropped 160 points or 1.71% to settle at 9,154. Major laggards in the Sensex pack lost as much as 8.74%.