By South Korea’s stock market suffered one of its sharpest declines of the year after the benchmark KOSPI plunged more than 8%, triggering an exchange-wide circuit breaker as heavy selling in semiconductor stocks rippled across Asian markets.
The Korea Exchange suspended trading for 20 minutes after the KOSPI remained more than 8% below the previous session’s close for at least one minute, activating one of the market’s strongest stabilization mechanisms. The halt came after the index fell to around 6,212 points before partially recovering when trading resumed. The selloff was led by memory-chip giant SK Hynix, whose US-listed American depositary receipts (ADRs) closed at approximately $143 in New York, falling below their $149 initial US listing price. The decline spilled into Seoul trading, where SK Hynix shares dropped more than 10%, while Samsung Electronics fell more than 9%. Together, the two companies account for over half of the KOSPI’s market capitalization, amplifying the impact on the broader index. The sharp move reflected growing investor concerns that the extraordinary rally in artificial intelligence-related semiconductor stocks may have outpaced near-term fundamentals.
AI and China Fears Drive Semiconductor Selloff
Several factors combined to pressure chip stocks. Investors continued reassessing valuations across the AI supply chain after recent weakness in major US semiconductor names. At the same time, concerns intensified over China’s rapid advances in memory-chip manufacturing following the strong stock market debut of ChangXin Memory Technologies (CXMT) and reports that Chinese firms had made further progress in domestic lithography equipment.
The developments raised fears that Chinese manufacturers could accelerate production capacity and compete more aggressively with established South Korean memory leaders over the coming years. Analysts also pointed to growing questions surrounding the pace of AI infrastructure spending. After nearly two years of exceptional gains driven by demand for high-bandwidth memory chips used in AI servers, investors have become increasingly sensitive to any signs that spending growth could moderate or competition could intensify. Because SK Hynix is one of Nvidia’s largest suppliers of advanced HBM memory, its shares have become closely tied to investor sentiment surrounding the global AI investment cycle.
Circuit Breaker Highlights Market Stress
The activation of a KOSPI circuit breaker underscored the severity of the selling pressure. Unlike ordinary volatility interruptions affecting individual stocks, the market-wide mechanism temporarily halts trading when losses become sufficiently large, giving investors time to reassess conditions and helping reduce disorderly market activity. According to the Korea Exchange, this was the eighth circuit breaker triggered on the KOSPI this year.
Despite the dramatic decline, analysts cautioned that the move reflected a broad repricing of AI-related equities rather than company-specific operational problems at SK Hynix or Samsung Electronics. Investors will now closely monitor upcoming earnings, AI infrastructure spending plans and competitive developments in China’s semiconductor industry to determine whether the latest selloff represents a temporary correction or the beginning of a more prolonged reset for global chip stocks.
Given the heavy weighting of semiconductor companies within South Korea’s equity market, any sustained weakness in AI-related shares is likely to remain the dominant driver of the KOSPI in the weeks ahead.