South Korea’s stock market suffers its worst day in months as Samsung and SK Hynix plunge on spending doubts and China’s new tools.
South Korea’s KOSPI index tumbled 10.84% on Tuesday, closing at 6,023.66 after repeated circuit-breaker halts. The drop marked its sharpest single-day loss since March and wiped out hundreds of billions in market value.
Samsung Electronics fell 13.4%—its worst session in nearly two decades—while SK Hynix dropped 14.7%. The two memory giants make up nearly half the index, so their collapse dragged the entire market lower. Japan’s Nikkei also slid about 4%.
Why the Sudden Rout
Investors fled after two overlapping worries hit at once. First, questions grew over whether Big Tech’s massive AI data-center spending can keep rising at the same pace. A Wall Street Journal report that Nvidia might backstop roughly $250 billion in financing for an OpenAI project rattled markets. Traders began asking whether chip makers are effectively funding their own customers.
Second, fresh reports showed China has started limited mass production of domestic immersion deep-ultraviolet (DUV) lithography machines. State-backed teams, drawing on startups including Yuliangsheng, aim to deliver about five systems this year to SMIC, Hua Hong, and ChangXin Memory Technologies (CXMT), with roughly 20 planned for 2027. These tools can print 28-nanometer features in a single exposure and reach finer nodes through multi-patterning.
Analysts at Kiwoom Securities said the news rekindled fears that Chinese memory producers could expand capacity faster, pressuring prices and market share for Korean suppliers of high-bandwidth memory used in AI accelerators.
Wider Fallout and What’s Next
SK Hynix’s newly listed U.S. shares closed below their $149 IPO price for the first time. CXMT’s strong Shanghai debut the day before added to oversupply concerns in commodity DRAM, even if Korean firms still lead in advanced HBM.
The selloff spilled into other Asian chip names and kept pressure on U.S. semiconductor stocks. Markets now watch SK Hynix’s earnings due Wednesday, a string of Big Tech results later this week, and the Federal Reserve’s policy decision.
For years Korean memory makers rode the AI boom to record valuations. Tuesday’s crash shows how quickly that narrative can reverse when spending doubts and geopolitical catch-up collide.
for those just waking up…
— PairSync (@PairSync) July 28, 2026
KOSPI PLUMMETS 10.84% IN HISTORIC SINGLE-DAY CRASH AS SAMSUNG AND SK HYNIX LEAD MASSIVE SEMICONDUCTOR SECTOR BLOODBATH. pic.twitter.com/djQTx2t7NS