Mumbai, April 14 -- Benchmark stock indices Sensex and Nifty closed nearly 1% lower on Monday as the failure of US-Iran negotiations heightened concerns of a prolonged conflict driving crude oil prices sharply higher. The 30-share BSE Sensex tumbled 702.68 points or 0.91% to settle at 76,847.57. During the day, it dived 1,681.93 points or 2.16% to 75,868.32. The 50-share NSE Nifty plunged 207.95 points or 0.86% to end at 23,842.65. From the 30-Sensex firms, Maruti, InterGlobe Aviation, Bajaj Finance, Reliance Industries, Tata Consultancy Services and HDFC Bank were the biggest laggards. ICICI Bank, NTPC and Axis Bank were the winners. The US and Iran failed to reach a peace deal at their historic 21-hour talks in Pakistan, leaving the fate ...