Samsung, SK hynix gain over 5% as Reuters reports China fab upgrades

Shares of Samsung Electronics and SK hynix each rose more than 5% in Seoul on October 21, 2026. Samsung finished at 223,500 won (US$168.65), up 5.67% from 211,500 won a session earlier. SK hynix ended at 1,294,000 won (US$976.46), a 5.81% gain from 1,223,000 won.

That afternoon, at 13:49 Korea time, Reuters reported that both companies are upgrading their factories in China so those plants can turn out more advanced chips. Reuters cited people it did not name. CNBC carried the Reuters story at 14:44. Neither company has commented on the report, and no outlet tied it to the day’s share gains.

What outlets say is changing in China

The reported plans span both main types of memory. TrendForce reported that the two chipmakers are taking their Chinese NAND flash lines beyond 200 layers as pressure from Chinese rival YMTC grows. NAND flash is the storage memory used in phones and data-center drives, and more stacked layers pack more data onto each chip. DigiTimes reported that the NAND plant work is going ahead as the US position on such upgrades eases.

Tom’s Hardware reported that the work also extends to advanced DRAM, the working memory in computers and servers. It described the move as an answer to CXMT and other Chinese competitors at a time of strong AI data-center demand. A Pacific Tape guide sets out which companies make DRAM and NAND.

The competitive pressure is already visible in one market. YMTC has overtaken Samsung in China’s NAND flash market, the Korea Economic Daily reported on Oct 21.

All of these accounts come from media and analysts, not from the companies. Samsung and SK hynix have not said what equipment or investment the work would involve.

A rebound that beat the index

The broader Korean market also climbed. The KOSPI closed at 5,735.66, up 3.29%, and the TIGER 200 exchange-traded fund rose 3.35% over the same session, so both chipmakers ran ahead of the market. That weighs heavily on the index: Samsung alone made up 29.94% of the KOSPI 200’s total market value on Oct 21.

For investors holding the shares in dollars, Samsung’s gain came to 5.9%. It was the stock’s biggest one-day rise since Sept 7, 2026, when it added 5.68%, 27 sessions earlier.

⤢

The day’s move recovered only part of a steep decline. From Sept 29 through Oct 21, Samsung lost 17.98% in won and 16.04% in dollars. SK hynix fell further over the same stretch, down 26.69% in won and 24.94% in dollars. Pacific Tape covered the sharpest part of that slide in the worst week for both stocks since 2008.

Earnings calls next week

Both companies report third-quarter results soon. SK hynix holds its earnings conference call on Oct 28 at 09:00 KST. Samsung holds its call on Oct 29 at 10:00 KST.

---

Information only, not investment advice.