KOSPI Plummets 5.81% as Samsung and SK Hynix Lead Tech Rout

The Korea Exchange activated a marketwide circuit breaker on Friday, June 26, 2026, halting trading for 20 minutes after the benchmark Korea Composite Stock Price Index (KOSPI) plummeted more than 8% during the session. The index eventually closed down 5.81%, falling 519.09 points to 8,411.21. This event marked the fifth circuit breaker activation of the year and the first time in the market's history that such halts occurred twice within a single week, following a weekly crash of over 16%.

The slump was driven by a massive sell-off in semiconductor giants Samsung Electronics and SK Hynix, which together comprise roughly 60% of the index's market capitalization. These stocks fell between 5% and 10% as investors reacted to Apple Inc. raising product prices due to memory chip shortages and rumors of a delayed initial public offering for OpenAI. Market volatility was further fueled by concerns over the sustainability of global AI infrastructure investments, which are projected to exceed $700 billion in 2026.

While retail investors purchased over 9 trillion won in shares, foreign and institutional investors sold a combined 9.82 trillion won. Other sectors also declined, including Hana Financial Group and LIG Defense & Aerospace. The crash mirrored a broader Asian tech rout affecting Japan's Nikkei 225 and Taiwan's Taiex. In the foreign-exchange market, the South Korean won strengthened to 1,532 per dollar, amid suspected government intervention.