Mumbai, May 21 -- Falling for the third day in a row, benchmark stock indices Sensex and Nifty tumbled 1% on Tuesday dragged down by profit taking in blue-chips such as HDFC Bank, Reliance Industries and ICICI Bank. Retreating from early highs, the 30-share BSE Sensex tanked 872.98 points or 1.06% to settle at 81,186.44. During the day, it dropped 905.72 points or 1.10% to 81,153.70 as profit taking emerged in auto, financials and defence stocks.P12...