Asian chip stocks sold off hard for a second straight day on Tuesday. The Kospi opened down 3.10% at 6,186.08 in Seoul and the losses deepened through the morning, with the index down more than 6% by 10:40 a.m. local time. Samsung Electronics was down 8.8% and SK Hynix down 9.3% at that point, both at their lowest levels since August, after falls of 4.4% and 4.5% respectively in Monday’s session. Foreign investors were net sellers of 948.8 billion won of main-board shares in early trading, the Seoul Economic Daily reported, citing Korea Exchange data.
The trigger is Chinese competition in memory. ChangXin Memory Technologies says it has made progress on a 4F-squared DRAM cell architecture, which could cut cell area by roughly a third against the dominant 6F-squared structure, and plans to launch DDR5 server memory using the technology by year-end. That challenges the assumption underpinning record Korean memory margins, that advanced supply stays concentrated among a handful of producers. The move followed a weak US session on Monday, when the Philadelphia Semiconductor Index fell 2.7%, Micron lost 3.9% and SanDisk 6.0%.
Japan followed Seoul lower as Tokyo reopened after Monday’s holiday. SoftBank Group fell about 8%, with Tokyo Electron down about 6.7% and Advantest about 5.7% in CNBC’s reporting, as the same doubts about AI returns and financing costs hit the region’s most AI-exposed names. The macro backdrop compounded the move: Brent traded around $105.90 a barrel and the US 10-year Treasury yield sat near 5.21%, close to last week’s 24-year high, raising the discount rate applied to future AI profits.
The counterpoint is that CXMT has not yet shown it can manufacture the new architecture reliably at scale, and yields, performance and customer certification are unverified, as the Seoul Economic Daily noted. Samsung forecast record quarterly operating profit of 107.4 trillion won only last week. Earnings from TSMC and ASML later this week are the next hard test of whether this is a repricing of the memory cycle or a deeper break in the AI trade.