KOSPI Triggers Second Circuit Breaker in One Week: Is AI Chip Mania Cracking?
South Korea's KOSPI triggered its second circuit breaker in a single week on Friday, plunging 8.19% intraday and wiping out $350 billion in market value, as AI chip-related panic spread across global markets. The cascade is now widely viewed as the clearest signal that AI chip exposure has become the dominant risk factor for equities worldwide.
South Korea's benchmark stock index, the KOSPI, has become the canary in the global coal mine for AI-driven market risk. After suffering a near-10% crash on Tuesday, the index triggered yet another emergency trading halt on Friday — its fifth circuit breaker of 2026 — signaling that the AI chip trade has evolved into the single biggest systemic threat facing global equities today.
On Friday, June 27, 2026, the Korea Exchange activated a circuit breaker at 12:10 p.m. local time after the KOSPI remained more than 8% below its previous close for over a minute. The index plunged 731.97 points, touching 8,198.33 at the point of suspension before recovering slightly to close at 8,411.21 — still down 5.81% on the session. The Friday selloff also made history as only the second time a sell-side sidecar and a circuit breaker were both triggered within the same trading session.
Over the course of the week, the South Korean market shed roughly 10% of its total value, erasing approximately ₩550 trillion — equivalent to $350 billion — from market capitalization. The destruction was concentrated in the semiconductor sector. Samsung Electronics fell 5.30% to 339,500 won (~$248 per share), while SK Hynix dropped a brutal 8.36% to 2.673 million won (~$1,950). These two chipmakers together represent nearly half of the KOSPI's total market cap, meaning their moves are essentially amplified versions of broader index sentiment.
Capital flight was staggering. Foreign investors offloaded a net 4.62 trillion won (~$3.4 billion) during Friday's session alone, with institutional investors adding another 3.78 trillion won (~$2.8 billion) in sales. Retail investors, however, moved in the opposite direction — buying a net 8.19 trillion won (~$6.0 billion), apparently committed to the long-term AI infrastructure thesis despite the chaos.
What sparked the latest collapse? Analysts point to a convergence of pressures: mounting concerns over slowing memory chip demand, pricing friction between Apple and Micron, escalating worries about AI infrastructure costs, and reports suggesting a potential delay in OpenAI's highly anticipated IPO. Earlier in the week, the KOSPI had rebounded 5% on Wednesday and another 3% on Thursday following Tuesday's massive crash. That recovery, however, set the stage for aggressive profit-taking and forced selling from passive funds tracking semiconductor-heavy indexes.
The fallout spread far beyond Seoul. Japan's Nikkei 225 dropped 4.15% on Friday to 69,360.83, erasing Thursday's gains and falling back below the psychologically important 70,000 level. SoftBank plunged more than 12% in Tokyo amid reports about the uncertain OpenAI IPO timeline. On Wall Street, the Nasdaq Composite posted its fifth straight losing session, shedding 4.6% for the week. The S&P 500 lost nearly 2% over the same period, while the Philadelphia Semiconductor Index extended a rout that had already swept through Asia and Europe.
The structural takeaway is impossible to ignore. Because Samsung and SK Hynix account for more than half of the KOSPI, any significant shift in memory chip sentiment instantly becomes an index-level event. KOSPI-linked instruments now function less as traditional Korean equity products and more as pure proxies for global AI chip sentiment.
Until the AI chip trade finds more stable ground — anchored by clearer demand signals, healthier pricing dynamics, and firmer timelines for major tech IPOs — Seoul's circuit breakers will likely continue to serve as the earliest warning system for stress building across the entire interconnected global market.
