South Korea’s benchmark KOSPI index fell back 9.99% today, as a brutal selloff in semiconductor giants Samsung Electronics and SK Hynix triggered circuit breakers and wiped hundreds of billions of won from the market in a violent pullback of the AI trade.
The KOSPI closed at the low of the day (8,203.84), down 910.71 points, feeling the weight of the megacaps that have so far driven the index to a 90% gain YTD. Samsung Electronics shares, the index’s largest constituent, plummeted 12.31% while SK Hynix share price gave back 12.47%, both retreating sharply from all-time highs. The severity of the selloff briefly triggered volatility controls as futures markets hit their downside limits, forcing a temporary trading halt that underscored the ferocity of the deleveraging.
The two semiconductor giants together account for roughly 54% of the KOSPI’s market cap, and have become the main focal points for Korea’s share market. Their combined decline mechanically dragged the entire index lower, with the concentration that had supercharged gains on the way up now amplifying losses
Driving The Move
The immediate trigger for Tuesday’s rout was a continuation of profit-taking that began after comments from Alphabet on AI commoditisation sent shocks through global semiconductor markets. The Alphabet share price fell 5.08% in Monday’s session for one of the worst day’s in recent memory, and markets have continued to sell down overnight, with Nvidia 2.9% lower pre-market, AMD down 5.7%, Intel shares off by 7.71%, and Micron down 8.2%. Korean markets open after U.S. trading closes, bearing the brunt of the follow-through selling today.
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The selloff represents a sharp reversal for stocks that had been among the world’s best performers on the back of insatiable demand for high-bandwidth memory (HBM) chips used in artificial intelligence systems. Volatility does work in both directions, and sharp moves to the upside can be aggressive if sentiment shifts.
Korean semiconductors have become extremely crowded, with both foreign institutional investors and domestic retail traders piling into the AI theme. That concentration left the market vulnerable to any shift in sentiment, and recent commentary from global semiconductor companies suggesting a more measured pace of AI infrastructure spending provided the catalyst for a broad de-risking.
The AI rally is taking a breather after a breakneck rally, but if this turns into a more pronounced period of selling, the KOSPI will come under pressure.
The sharp correction in the KOSPI today serves as a reminder that even the most compelling structural growth stories are not immune to violent de-risings when positioning becomes one-sided and valuations stretch. Whether Tuesday’s plunge marks a healthy reset or the beginning of a deeper retracement will depend on the durability of AI infrastructure spending and the willingness of markets to look through near-term volatility to the multi-year HBM demand trajectory that underpins the bull case.
Bull Case:
- HBM capacity sold out; structural AI memory demand intact for multi-year cycle
- Selloff driven by crowded positioning and profit-taking, not fundamental deterioration
- Nvidia partnerships and AI factory investments confirm Korea’s strategic role
- Sharp correction creates attractive entry point for long-term AI exposure
- Potential MSCI Developed Markets inclusion could trigger sustained foreign inflows
Bear Case:
- Extreme concentration in two stocks magnifies volatility and index downside risk
- Samsung execution risk in closing HBM gap; could lose share to SK Hynix
- Global semiconductor sentiment fragile after Broadcom warning and Philly Semi decline
- Macro headwinds from oil dependence and geopolitical risk compress margins
- Forced liquidations and circuit breakers signal fragile market structure and leverage
