Shares of Micron (MU) and SK Hynix (SKHY) are poised to open lower on Tuesday, extending a global sell-off in memory-chip stocks as South Korea's benchmark KOSPI (^KS11I) tanked 6%.

In South Korea, SK Hynix (000660.KS) and Samsung Electronics (005930.KS) each fell roughly 8%, extending their losing streaks to five sessions. The two chipmakers account for more than half of the South Korean stock market's total capitalization.

The sell-off was a continuation of market reaction after Chinese memory maker CXMT (688825.SS) announced progress on a new memory-cell design engineered to pack more storage into less physical space.

CXMT aims to introduce a new server memory product built on this architecture by the end of 2026.

The advance threatens to intensify competition for Samsung, SK Hynix, and US-based Micron, which together account for roughly 90% of the global DRAM market.

Micron, SK Hynix, and Samsung have been major beneficiaries of the AI trade over the past year amid surging demand for memory and storage chips driven by the global AI data center build-out. All three memory makers reached $1 trillion valuation over the summer.

Last week, Samsung reported a preliminary record third quarter profit of $80 billion, but the forecast did little to lift the rest of the chip sector,

Micron posted strong quarterly results in September. The stock is up roughly 240% year-to-date.

Ines Ferre is a senior business reporter for Yahoo Finance.

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