South Korea's Kospi drops 8%, triggering circuit breaker

On October 15, South Korea's benchmark Kospi index plunged more than 8%, triggering the market's circuit breaker mechanism and suspending trading for 20 minutes. This event marks the tenth time the South Korean stock market has activated a circuit breaker this year, according to news.china.com.

Market Performance and Individual Stocks

The Kospi extended a seven-day losing streak, with a cumulative decline of approximately 21% over that period, its longest run of losses since September 2024. The index closed at 5,554.22, down 454.59 points or 7.57%, according to finance.biggo.com. During the session, the index briefly fell as low as 5,450.81, breaking below the 5,500 level before recovering slightly.

The sell-off heavily impacted major technology companies. SK Hynix fell more than 11%, while Samsung Electronics dropped nearly 10%. These two companies carry significant weight in the Kospi, and their decline directly amplified the index's drop. The KOSDAQ index also suffered, closing down 63.06 points or 7.65% at 760.82.

Causes: Inflation and AI Concerns

The immediate catalyst for the decline was hotter-than-expected U.S. inflation data. The U.S. Consumer Price Index for September rose 0.6% month-on-month and 3.7% year-on-year, exceeding market expectations. This data raised concerns that the Federal Reserve might keep interest rates elevated for longer, increasing financing costs for capital-intensive industries.

Investors also expressed skepticism about the profitability of artificial intelligence (AI) investments. Concerns grew that massive capital deployed into AI infrastructure is not translating into revenue and profit quickly enough. This sentiment weighed heavily on semiconductor giants like Samsung Electronics and SK Hynix, which are core players in the global DRAM and high-bandwidth memory (HBM) supply chains.

Regional Impact and Leveraged ETFs

The tech sell-off spread across Asia. Japan's Nikkei 225 index fell about 5%, with companies like SoftBank Group and Kioxia leading the decline. Kioxia dropped more than 11%, while SoftBank fell over 9%. Taiwan's TAIEX also declined, closing down 3.41%.

The volatility caused significant losses for investors in single-stock leveraged ETFs. TIGER SK Hynix Single-Stock Leverage closed at ₩5,740, representing a 71.3% decline from its May listing reference price of ₩19,985. Despite these losses, retail investors net purchased approximately ₩78 billion (approximately $58 million) of these products over the past month, betting on a rebound.

Why it matters

The repeated triggering of circuit breakers in South Korea highlights the fragility of markets heavily dependent on the semiconductor sector during periods of global AI investment adjustment. The convergence of rising U.S. interest rates and doubts about AI profitability has led to a sharp recalibration of valuations. Analysts note that market volatility may persist until there is greater clarity on U.S. interest rate trajectories and the sustainability of AI capital expenditures. The situation also underscores the risks associated with leveraged financial products during high-volatility periods, as seen in the substantial losses suffered by retail investors in SK Hynix-linked ETFs.

---

Sources

• news.china.com (in Chinese): South Korean stock market plunges 8%, triggering circuit breaker for the tenth time this year; trading suspended for 20 minutes
• tradingkey.com: South Korea’s Kospi Plunges 8% to Trigger 10th Circuit Breaker This Year; SK Hynix, Kioxia Drop Over 11% as AI Funding Worries Sweep Asia
• finance.biggo.com: South Korea's KOSPI Plunges 7.57% in 'Black Thursday' — Circuit Breaker Triggered for First Time in Two and a Half Months — BigGo Finance
• businesstoday.in: KOSPI Crash: South Korea triggers trading halt as Samsung, SK Hynix tumble - BusinessToday

This article was drafted with AI assistance and checked against the sources above. Company claims are reported as claims. Cover image is AI-generated.