South Korea and Taiwan have tumbled in global stock market capitalization rankings as a deepening selloff in AI and semiconductor stocks wipes out much of the region's recent AI-fueled rally, with the Korea Exchange forced to briefly halt trading Tuesday as the Kospi plunged as much as 11%.

The Scale of Tuesday's Selloff

South Korea was at the center of the turmoil, with the benchmark Kospi falling by around 10%, briefly extending losses beyond 11%, forcing the Korea Exchange to halt trading for 20 minutes after the index remained more than 8% below Monday's close. Japan's Nikkei 225 dropped more than 4%, while Taiwan's Taiex lost close to 5% as investors aggressively reduced exposure to chipmakers and other companies tied to the global AI boom. China's Shanghai Composite also traded lower, though its decline was considerably smaller, while Hong Kong showed greater resilience and Australia's ASX 200 managed modest gains.

How This Is Reshaping Global Market Cap Rankings

The correction has already produced measurable shifts in country-level rankings. India reclaimed the fifth spot in global market capitalization rankings in late June after briefly slipping to seventh, as sharp corrections in Taiwan and South Korea dragged both markets lower. At that point, India's total market cap stood at $5.05 trillion, while Taiwan and South Korea had fallen to sixth and seventh position with valuations of $4.97 trillion and $4.66 trillion respectively — both dropping below the $5 trillion mark for the first time in the ranking cycle. The United States remained the world's largest market, followed by China, Japan, and Hong Kong.

Why Taiwan and Korea Are Getting Hit Hardest

The concentration of losses in South Korea and Taiwan reflects how heavily both markets' recent gains were driven by a narrow set of AI-linked mega-caps. South Korea's Kospi had surged roughly 80% since April, with more than a third of those gains coming in just the past month, fueled by Samsung Electronics rising 90% this year and SK Hynix more than tripling. Taiwan's benchmark index had advanced 22% this year, driven mostly by a 40% rally in TSMC shares. That same concentration now works in reverse: even relatively moderate declines in TSMC can have an outsized effect on the Taiex given the company's enormous index weighting, meaning Taiwan's broader market has suffered some of the largest declines in the region as the global chip selloff intensified.

The Toll on Individual Chip Stocks

Chip stocks have collectively shed more than $1 trillion in market value during the selloff. AMD lost around $110 billion and TSMC lost $119 billion. Japan's Kioxia fell 13.85%, Tokyo Electron dropped 10.59%, and SoftBank Group — a major AI investment proxy through its stake in Arm — lost 6.95%. South Korean stocks accelerated their declines further on Wednesday, with concerns over the rise of Chinese chipmakers driving the Kospi below a critical threshold and wiping out earlier gains from the AI-led rally, even as SK Hynix reported robust earnings the same day.

What's Driving the Reassessment

Kieron Poon, investment director of Asian equities at Aberdeen Investments, attributed the latest weakness to "the ongoing deleveraging process in Korea and softer sentiment towards global technology stocks," while stressing the volatility "has not changed our long-term positive view." Michael Field, chief equity strategist at a separate firm, characterized the decline as being "driven largely by sentiment rather than fundamentals" — a distinction that suggests the selloff reflects a repricing of AI-related risk and valuation concerns rather than a deterioration in the underlying chip demand story.

Not a Uniform Regional Crash

The selloff has been notably concentrated rather than universal. Australian shares traded modestly higher, benefiting from the country's smaller exposure to semiconductor companies and continued declines in oil prices. Hong Kong also performed better than Japan, South Korea, and Taiwan, while mainland Chinese losses remained comparatively contained — mainland China's tech-heavy ChiNext 300 index actually gained 1.43% even as the Hang Seng China Semiconductor Chips Index fell 2.5%.

What's Next

With South Korea and Taiwan's market cap rankings now directly tied to the fate of a handful of AI-linked mega-caps, further volatility in chip stocks is likely to keep reshuffling the global rankings in the weeks ahead. Investors will be watching closely for whether the current selloff proves to be a healthy repricing of stretched valuations, as some analysts argue, or the start of a more sustained reassessment of the AI investment cycle that powered both markets' historic gains earlier this year.