Sensex, Nifty down: What caused the stock market crash today?

INdian stock up markets tumbled on mon, as persia and the United States failed to touch an accord during the talks in Pakistan's Islamabad over the weekend.Around opening time, at 9:15am, the 30-share S&P BSE Sensex fell 2.08 per cent to 75,937.20 points, while the 50-share NSE Nifty plunged 1.92% to 23,589 points.During the initial trade, all the 30-Sensex firms were trading in the lower trend, with Titan, Sun Pharma, NTPC, Bharat Electronics, Power Grid, and Bharti Airtel being the biggest laggards. Follow US-Iran war news live updatesMeanwhile, Brent crude, the global oil benchmark, surged 7.33 per cent to $102.2 per barrel.Stock markets todayMarkets remained down for the better part of the day on Monday, with the Nifty 50 trading 0.94 per cent or 227.25 points lower at 23,809.90, as of 12:27pm.Meanwhile, the BSE Sensex was trading 1.02 per cent or 789.93 points lower at 76,760.32 at 12:27pm.ALSO READ | ‘Don’t care if they come back': Trump after failed US-Iran talks in Pakistan; says Tehran in ‘very bad shape’At this time, 25 of the 30 Sensex firms were trading at a loss, with HDFC Bank, IndiGo, Bajaj Finance, Reliance, and Maruti experiencing the maximum loss. What caused the stock market crash today?The bleeding markets are a result of the failure of the US-Iran talks in Islamabad over the weekend. US vice president and chief negotiator JD Vance announced at a press briefing on Sunday that he and his team were returning to Washington without a deal as Iran refused to accept what he described as America's "best and final offer".Meanwhile, Iran blamed the failure on the "unreasonable demands" presented by the US, which included mentions of the Strait of Hormuz and Tehran's nuclear programme.Later in the day, US President Donald Trump blasted Iran over the talks and announced that the American navy will begin a blockade of ships entering and exiting the Strait of Hormuz from 10am (local time) on Monday.ALSO READ | Deal was just ‘inches away’: Iran FM shares what happened in talks with USHe said that he doesn't care if Iran comes back to the table or not, adding that Tehran's capabilities have been depleted and defeated. "Iran is in a very bad shape," he told reporters on Sunday night.VK Vijayakumar, chief investment strategist at Geojit Investments Limited, told news agency PTI, "With the failure of US-Iran peace talks and Trump's declaration of US naval blockade in the Strait of Hormuz, uncertainty and along with it crude price have spiked. Brent at USD 103 is emerging as yet another threat to the economy and markets."The development has "triggered a clear risk-off sentiment across global markets," said Hariprasad K, Research Analyst and Founder, Livelong Wealth.Additionally, Asian markets, including South Korea's benchmark Kospi and Japan's Nikkei 225 index, were also trading lower.