South Korean KOSPI triggers circuit breaker after 8 percent plunge on chip selloff and AI financing fears

South Korea's benchmark KOSPI index fell 8.0 percent to 5,528.05 on October 15, triggering a circuit breaker that halted trading for 20 minutes at 12:38 pm Seoul time, marking the tenth activation this year and the sixteenth in the index's history, according to the Korea Exchange and multiple media reports. Samsung Electronics dropped 9.7 percent and SK Hynix fell 11.35 percent during the session as chipmakers tracked a technology-led Wall Street selloff following persistent US inflation data that raised expectations of further Federal Reserve rate hikes. The KOSPI fell for a seventh consecutive session, its longest losing streak since September 2024, and closed the day down 7.7 percent at 5,548.78. The sharp decline followed the Philadelphia Semiconductor Index dropping 4.3 percent overnight on October 14 as AI-linked stocks came under pressure from concerns over whether companies funding AI infrastructure can sustain spending at current elevated financing costs. Analysts told Reuters and other outlets that the market is shifting from focusing on AI revenue growth to questioning whether capital raising will be sustainable and whether massive infrastructure investment will generate real income. The KOSPI is now more than 40 percent below its 52-week peak of 9,385.59.

South Korea's concentration in memory chips and its role as a proxy for hyperscaler and data-center spending makes the index particularly vulnerable to any reassessment of AI infrastructure economics. The constraint is whether Samsung, SK Hynix, and their customers can sustain current capital expenditure levels if financing costs remain elevated.

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Reuters via Investing.com, South Korea's KOSPI triggers circuit breaker in tech-led selloff, published October 15, 2026, investing.com Investing.com, KOSPI hits near 3-month low as 8% plunge triggers circuit breaker, published October 15, 2026, investing.com Invezz, Here's why the KOSPI crashed 8% and triggered a circuit breaker on Oct. 15, published October 15, 2026, invezz.com The Korea Herald, Seoul shares crash over 7% on chip rout amid AI, inflation woes, published October 15, 2026, koreaherald.com SBS News, KOSPI and KOSDAQ Trigger Level 1 Circuit Breakers Amid Plunge of Over 8%, published October 15, 2026, news.sbs.co.kr