The South Korean stock market, particularly the benchmark KOSPI index, experienced its worst single-day drop in history on March 4, 2026, plunging over 12% and wiping out hundreds of billions in market value. 0 This followed a 7.2% decline the previous day, marking the steepest two-day sell-off since the 2008 financial crisis. 2 The primary driver is the escalating US-Israeli war on Iran, which has intensified Middle East tensions and sparked fears of global energy supply disruptions. 1 South Korea, as the world’s eighth-largest crude oil importer and heavily reliant on Middle Eastern supplies (importing nearly all its oil), is particularly vulnerable to surging oil prices and potential interruptions in maritime trade through key routes like the Strait of Hormuz. 4 Higher energy costs could fuel inflation, slow economic growth, and erode corporate profits in Asia’s fourth-largest economy. 5
Compounding factors include:
- Panic selling and leverage unwind: The KOSPI had been one of the world’s top performers earlier in 2026, doubling over the past year amid an AI-driven boom in tech stocks like Samsung Electronics (down 11.7%) and SK Hynix (down 9.6%). 2 Record levels of margin debt and leveraged bets among retail investors led to forced liquidations and margin calls, accelerating the rout. 6
- Currency weakness: The Korean won weakened past 1,500 per USD for the first time since the 2008 crisis, hitting a 17-year low, as investors fled to safe-haven assets like the dollar amid risk-off sentiment. 3
- Broader global fallout: The conflict has hammered equities worldwide, but Korea’s losses outpaced other Asian markets due to its energy dependence and recent overvaluation. 12 Trading halts (circuit breakers) were triggered multiple times on the KOSPI and KOSDAQ indices to curb volatility. 9
South Korean authorities have vowed to intervene with market stabilization measures, including a potential KRW 10 trillion fund, to address excessive volatility. 18 While the immediate trigger is geopolitical, analysts note that profit-taking after the market’s strong run-up also played a role, with concerns that rising energy costs could slow AI data center adoption and broader tech growth. 8