Kospi index plunges as AI chip sell-off hits Asia stocks
The kospi index tumbled roughly 10% on Tuesday after a circuit-breaker pause, as AI jitters hammered chipmakers from Seoul to Wall Street. Samsung Electronics and SK Hynix led the slide, following Nvidia’s 5% drop that handed Apple the crown as the world’s most valuable listed company.
For readers tracking portfolios and wealth hacks and passive income ideas, the move matters because South Korea’s tech-heavy benchmark is a live gauge of confidence in the AI spending cycle. When memory-chip giants wobble, global AI-linked equities often follow.
Key Takeaways
- The kospi index was halted after an 8% slide, then traded around 10% lower once the 20-minute pause ended.
- Samsung Electronics and SK Hynix fell by roughly 12% or more, extending a Wall Street chip rout led by Nvidia’s 5% drop.
- Investors are questioning whether huge AI buildouts can pay off, while China’s CXMT soared nearly 470% on its Shanghai debut.
- Japan’s Nikkei 225 was almost 3.8% lower, and US semiconductor proxies such as the VanEck Semiconductor ETF also weakened.
- Analysts say long-term AI demand may remain large, but near-term visibility is poor and leveraged products can magnify swings.
Why did the kospi index trigger a circuit breaker?
Trading on South Korea’s benchmark kospi index was paused temporarily on Tuesday morning after the gauge slid by 8%. After the 20-minute halt was lifted, it fell further to trade around 10% lower, according to the BBC.
The tech-heavy kospi index has been halted eight times so far this year under the circuit-breaker mechanism designed to calm panic selling. The index had more than doubled from the start of the year to mid-June, but has since lost around a third of its value.
Recent months have been especially volatile in Seoul as large numbers of retail investors piled into the market. That crowd can amplify both rallies and sell-offs when sentiment toward AI hardware flips.
The local slump was led by technology firms. Samsung Electronics and SK Hynix both fell by about 12% in BBC reporting, while CNBC later tracked SK Hynix down more than 13% and Samsung Electronics down more than 12% as the sell-off deepened.
How far did chip stocks fall in the US and Asia?
The Asian session extended another weak day for US semiconductor shares. On Monday, Nvidia fell 5% in New York and lost its place as the world’s most valuable listed company to Apple, which has risen by about 25% this year.
US-listed shares in SK Hynix dropped 7.5% on Monday to well below the $149 offer price from its record-breaking Nasdaq debut on 9 July. In Seoul, related AI-linked names also sold off hard: Samsung SDI dropped over 10%, LG Innotek slid nearly 18%, Seoul Semiconductor fell about 7%, and LG Chem lost more than 6%.
Japan’s chip complex joined the decline. Tokyo Electron dropped almost 11%, Advantest slid over 10%, SoftBank Group fell 6.3%, and memory maker Kioxia plunged more than 18%. Japan’s Nikkei 225, also dominated by tech companies, was almost 3.8% lower on Tuesday morning.
Elsewhere in Asia, Taiwan’s TSMC was down 2.9%. Mainland China’s tech-heavy ChiNext 300 index fell 4.7%, while the Hang Seng China Semiconductor Chips Index dropped 5%.
On Wall Street, the VanEck Semiconductor ETF (SMH) lost more than 2%, adding to Friday’s losses. AMD and Teradyne dropped 5% and 4%, respectively, and Micron Technology shed about 2%.
What is driving AI investment jitters right now?
As governments and companies spend hundreds of billions of dollars on AI capabilities, some analysts have questioned whether the technology can become profitable enough to recoup such huge investments. Those doubts are colliding with fears of fiercer Chinese competition in memory chips.
Shares in China’s biggest memory chip maker, ChangXin Memory Technologies (CXMT), soared by nearly 470% on their Shanghai debut on Monday. CXMT said it plans to use most IPO proceeds to boost production and research. The firm makes DRAM chips used in AI data centres, phones, PCs, tablets and other devices.
Nvidia’s Monday drop followed a Wall Street Journal report that it is in talks to provide around $250bn for OpenAI as part of a massive data-centre project. The BBC said it had contacted Nvidia and OpenAI for comment.
Samsung Electronics and SK Hynix are among the world’s largest suppliers of high-bandwidth memory used in AI servers, so their shares are especially sensitive to shifts in expected spending by US hyperscalers. That linkage helps explain why Seoul’s kospi index can move so violently when AI narratives turn.
Acadian Asset Management’s Owen Lamont told CNBC that investors still have little visibility into how AI will ultimately affect the economy, calling the path “rocky.” He also warned that leveraged ETFs in Korea, Hong Kong and the United States may be magnifying market fluctuations.
Standard Chartered’s Sundeep Gantori said the sell-off also reflected media reports on China’s ambitions in memory chips and lithography equipment. He still sees a large long-term market opportunity for multiple players, noting broker reports around a memory-price peak in 2027 and arguing that risk-reward had improved at current valuations.
What should passive investors watch after this chip sell-off?
Even if you are not trading Korean shares directly, the kospi index is a useful stress test for AI-heavy portfolios, semiconductor ETFs and broader tech exposure. Sharp swings in HBM suppliers and Nvidia can ripple through index funds and retirement accounts that lean on megacap tech.
The episode underscores concentration risk: when a few AI-linked names dominate returns, profit-taking and competitive headlines can hit both active traders and set-and-forget investors. Diversification across sectors and geographies remains a practical buffer when circuit breakers fire in major Asian hubs.
Near-term volatility does not settle the longer debate over AI spending. Sources agree the opportunity looks large, yet profitability, Chinese capacity expansion and leveraged products are keeping markets jumpy. Watching whether the kospi index stabilises after the halt—and whether US chip proxies stop cascading lower—will tell investors if this is a short scare or a deeper reset in AI optimism.