South Korea Stocks Fall as Won Weakens on Oil Rally and Iran Tensions

South Korea’s financial markets moved lower on March 13, 2026. The benchmark Korea Composite Stock Price Index (KOSPI) finished down 96.01 points, or 1.72%, at 5,487.24. The tech-heavy KOSDAQ rose 4.56 points to close at 1,152.96.

In the foreign exchange market, the won weakened against the U.S. dollar. The Korea FX market tallied the weekly closing rate at 1,493.7 won per dollar as of 3:30 p.m., up 12.5 won from the previous session. After-hours trading saw the won briefly push past 1,500 per dollar, reaching 1,500.1 won.

Intraday, the won crossed the 1,500-per-dollar mark for the first time in seven sessions, after having touched an intraday high of 1,505.8 on March 4. The day’s mood reflected renewed pressure on the currency amid moves in oil markets and geopolitical headlines.

The price movements followed a sharp rise in global oil as tensions surrounding Iran intensified. Iran’s newly named supreme leader Seyyed Moztaba Hamenei announced a blockade of the Hormuz Strait, a crucial chokepoint through which a large share of world oil passes. The development sent crude prices back above $100 per barrel.

Earlier in the week, oil had already breached the $100 mark, contributing to pressure on the won and sparking caution in South Korean markets. By March 9, the won had traded around 1,495 per dollar as oil stayed elevated, even as President Donald Trump’s remarks had briefly calmed crude prices and provided temporary relief in some risk assets.

The Hormuz Strait closure prospect underscores how energy security and geopolitics can move global markets. Hormuz’s strategic importance means oil supply disruptions can rapidly translate into higher prices, influencing inflation expectations, central-bank policy, and financial conditions worldwide.

For U.S. readers, the episode matters because oil prices influence inflation and monetary policy in the United States, while Korea’s economy remains highly export-oriented and a major supplier of semiconductors and electronics. Currency moves in Korea can affect the cost of imported inputs for U.S. firms and the dollar value of Korean earnings, with potential implications for supply chains, pricing, and market sentiment in broader Asian markets.