A tide of red swept across global markets on Tuesday as semiconductor stocks suffered their worst single-day rout in years, triggered by a convergence of fears over AI spending sustainability, intensifying competition from China, and a record-breaking Chinese chip IPO.
South Korea bore the brunt of the selloff. The benchmark KOSPI index plunged more than 10% at one point, forcing exchange operators to temporarily halt trading for the first time since the pandemic era. Memory chip giants Samsung Electronics and SK Hynix — which together account for nearly half the index — collapsed 13.4% and 14% respectively.
"We seem to be at the despair part of the selloff, where tech investors are rushing for the exit," said Matt Simpson, senior analyst at StoneX.
The domino effect rippled across the region. Japanese flash memory maker Kioxia Holdings cratered nearly 18%, Taiwanese chip designer MediaTek fell more than 9%, and China's own markets slid over 2%. In Europe, Infineon dropped 4% and ASML shed 3%. US futures pointed to a weak open, with Micron down 6% in premarket trading.
The CXMT Bombshell
The immediate catalyst was the stunning market debut of ChangXin Memory Technologies (CXMT), China's leading memory chipmaker. The company's stock soared nearly 500% on Monday, instantly making it the most valuable company on the Shanghai exchange. The listing crystallized fears that Chinese competitors could soon challenge the South Korean and Japanese dominance of the memory chip market — a critical component of AI infrastructure.
"CXMT is going to be one of the big index weights," said Hao Hong, managing partner at Lotus Asset Management. "As that's going on, people have to dump more of their existing stocks."
Nvidia and the \$250 Billion Question
Compounding the anxiety, a Wall Street Journal report revealed that Nvidia could provide a roughly \$250 billion financial backstop for a massive OpenAI data center project in Ohio. The revelation sent Nvidia shares down nearly 5%, as investors questioned whether the AI chip leader was effectively financing its own customers — and what that meant for its balance sheet.
Meanwhile, OpenAI is reportedly nearing a deal to lease a \$500 billion data center in Ohio, underscoring the staggering scale of capital required to stay competitive in the AI arms race.
The Open-Source Wildcard
Adding another layer of uncertainty, the growing popularity of low-cost Chinese open-source AI models — notably Moonshot's Kimi K3, released just this week — has raised the possibility that future AI workloads could prove less compute-intensive than expected, potentially dampening demand for premium chips and high-bandwidth memory.
Earnings Season on Deck
The selloff arrives ahead of a packed week of earnings. Microsoft and Meta report Wednesday alongside SK Hynix. Apple and Amazon follow on Thursday, with Samsung Electronics also on deck. All eyes will be on whether these tech giants can justify their valuations amid mounting AI spending pressure.
"Despite stronger-than-expected earnings from Samsung and Alphabet last week, semiconductor shares experienced sharp declines after the results," noted Han Ji-young, an analyst at Kiwoom Securities.
With the Nasdaq down, the KOSPI in turmoil, and the specter of Chinese competition looming larger than ever, the AI-driven market rally that defined 2025 and early 2026 faces its most serious test yet.
