KOSPI Plunges Below 6,500 on U.S. Yield Surge

The KOSPI sank again on 19, falling more than 5% in a single session to drop below 6,500 points after previously trading above 7,000 intraday. A sell-side circuit breaker was triggered, and foreign investors—net buyers in recent sessions—sold more than 3 trillion won net. Analysts linked the move primarily to a U.S. rate shock as long-term Treasury yields surged. The 30-year yield hit 5.337% intraday, the highest since 2007, while the 10-year stayed around the 4.7% range. Concerns over larger U.S. Treasury supply, boosted by fiscal deficits and big tech corporate bond issuance for AI data centers, intensified bond-market supply pressure. Oil prices rising amid Middle East tensions further complicated Bank of Korea’s rate-cut plans and raised corporate funding costs.