BSE Sensex plunged 702 points on Monday to close at 76,847.57, while Nifty 50 index fell 208 points to close at 23,842.65. The fall comes as US-Iran peace talks failed in Islamabad and US threatened a blockade of Strait of Hormuz, leading to a spike in crude prices above $100/barrel. Auto and Oil and Gas indices were among top losers.