South Korea's benchmark Kospi index sank 7.9 percent on July 2, closing at 7,648.09 as renewed doubts over the sustainability of the AI buildout triggered a sharp sell-off in chipmakers. I have covered market corrections for over a decade, and what makes this one notable is concentration risk. Two stocks, Samsung Electronics and SK Hynix, now make up around half the Kospi's total weight, up from roughly a quarter at the end of last year.
What Triggered the Sell-Off
The drop tracked a rough start to July on Wall Street, where the tech-heavy Nasdaq Composite slumped overnight as investors dumped chip stocks. That move followed a similar panic in South Korea two weeks earlier, when the Kospi tumbled 10 percent and tripped a circuit breaker, forcing a 20-minute trading halt.
Key moves during the latest sell-off:
- SK Hynix dropped 14.6 percent to 2,187,000 won.
- Samsung Electronics fell 9.1 percent to 286,000 won.
- SK Square, SK Hynix's largest shareholder, fell 13.2 percent.
- Combined, the two chip heavyweights lost roughly 290 billion dollars in value in a single session.
Why Two Stocks Can Move an Entire Index
Samsung and SK Hynix's outsized weight means their swings ripple through the broader Kospi far more than in past years. Zavier Wong, market analyst at eToro, has pointed to this shift as a key reason the index has become more volatile as chip stocks reprice.
The Contagion Spread Across Asia
The sell-off was not isolated to South Korea. Regional markets moved in tandem as investors reassessed AI-related valuations:
- Tokyo's Nikkei 225 lost 2.5 percent to 68,733.15.
- Chip equipment maker Tokyo Electron shed 7.4 percent.
- Taiwan's Taiex declined 0.6 percent, with TSMC falling 1.6 percent.
- The Shanghai Composite fell 1.6 percent to 4,046.76.
Not every market moved lower. Hong Kong's Hang Seng rose 0.7 percent and India's Sensex climbed 0.5 percent, showing the pressure was concentrated in chip-exposed markets rather than broad-based risk aversion.
Wall Street's Role in the Decline
The Asian sell-off followed a rough Wednesday session in the United States, where Micron Technology shares dived more than 10 percent despite a 260 percent year-to-date gain, and Sandisk shed over 10 percent overnight. Other mega-cap names, including Nvidia and Broadcom, also declined between 1 and 2 percent.
Chinese AI names felt the pressure too. Knowledge Atlas Technology, the Hong Kong-listed entity behind AI model developer Zhipu, plunged more than 17 percent, while chip firm Shanghai Iluvatar CoreX Semiconductor dropped nearly 18 percent.
Investment Announcements Add Context
The sell-off came just days after major expansion announcements from South Korea's chip sector. SK Hynix CEO Kwak Noh-jung said the company plans to invest 100 trillion won, about 64.37 billion dollars, in South Korea, including a new fabrication plant targeted for operation in the first half of 2029.
SK Group also outlined plans to build AI data centers nationwide, starting with 5 gigawatts of capacity and scaling toward 15 gigawatts. That announcement followed a government initiative unveiled days earlier for Samsung Electronics and SK Hynix to invest a combined 800 trillion won in a national semiconductor ecosystem project.
SK Hynix is also set to begin trading American depositary receipts on the Nasdaq on July 10, a move that will widen access for U.S. investors even as near-term sentiment remains shaky.
What This Means for Investors
Despite the sharp declines, context matters. The prior Kospi plunge two weeks earlier was followed by a 3 percent rebound the next day, with Samsung recovering much of its losses in a 7 percent surge. Analysts have described these swings as recurring dips rather than a sustained reversal, since AI and chip demand fundamentals have not materially changed.
