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Seoul stocks fall 5.5% as China DRAM claim hits Samsung, SK hynix

The KOSPI posted its steepest drop since Aug. 19 after China’s CXMT said it would ship next-generation server memory by year-end and chip executives questioned returns on AI spending.

Motion Media News Staff

Oct 13, 2026

3 minutes

A tall cylindrical office tower with vertical KRX lettering and Korean script, beside other high-rise buildings under a hazy sky.

Photo: hyolee2, CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0), via Wikimedia Commons (cropped) (source)

South Korea's benchmark KOSPI index closed down 348.89 points, or 5.46%, at 6,035.35 on Tuesday, Oct. 13, its steepest one-day decline since Aug. 19, as the country's two largest chipmakers sold off, the Seoul Economic Daily reported. The index briefly dipped below 6,000 during the session, its lowest level since July 30.

Samsung Electronics ended 7.39% lower at 232,000 won, and SK hynix fell 10.09% to 1,443,000 won, the newspaper reported. The KOSPI now sits about 38% below its June all-time high, according to CoinDesk.

The CXMT claim

The selling followed remarks by Cao Kanyu, the head of ChangXin Memory Technologies (CXMT), China's largest DRAM maker. At an industry conference in Shanghai on Oct. 9 and 10, Cao said CXMT would release DDR5 server memory modules built on a 4F² cell design by the end of the year, the Seoul Economic Daily reported in a second story.

The 4F² layout shrinks each memory cell by about a third compared with the 6F² structure that dominates the industry today. The paper said Samsung aims to begin volume production of 4F² DRAM in 2028. Businesskorea cautioned that CXMT's planned product launch and Samsung's mass-production goal are different milestones that cannot be compared directly. CXMT says it holds more than 300 related patents, Businesskorea reported.

According to the Seoul Economic Daily, industry observers see the design as a workaround after U.S. sanctions blocked CXMT from buying extreme ultraviolet lithography tools from the Dutch company ASML. The paper added, citing Counterpoint Research, that CXMT's share of the global DRAM market rose to 10% in the second quarter from 4% a year earlier.

AI spending doubts

At a Singapore conference on Oct. 12, Broadcom CEO Hock Tan compared investors' position to sitting in a casino and called a lack of capital the biggest limit on AI expansion, the Seoul Economic Daily reported. Intel CEO Lip-Bu Tan cited rising capital costs at the same event. In the preceding U.S. session, Micron fell 3.88% and the Philadelphia Semiconductor Index dropped 2.67% to a three-week low, Businesskorea said.

Analysts urged caution about the CXMT announcement. Kiwoom Securities analyst Han Ji-young said it was too early to price in oversupply before CXMT shows the yields, performance and customer qualification its new products need, according to Businesskorea. Samsung and SK hynix expect 4F² to reach commercial use after 2028, and Goldman Sachs estimates CXMT's supply capacity will reach 41% of Samsung's and 50% of SK hynix's by 2028, the Seoul Economic Daily reported.

What's next

CXMT has not disclosed specifications, production yields or a mass-production date for the new modules. Kiwoom Securities put the KOSPI's near-term trading range at 5,500 to 7,000, the Seoul Economic Daily reported.