A Global Repricing Takes Hold

Memory and data-storage stocks plunged Thursday as selling pressure rippled across the semiconductor complex, extending a retreat from AI-linked equities that has gathered pace in recent sessions.

Western Digital fell 6.5%, Seagate dropped 6.1%, and U.S.-listed shares of SK hynix slid 4.8%. Micron lost 4.7% and SanDisk declined 4.1%, according to a trading snapshot. The declines are not closing returns and varied across sessions and listings; separate reporting had Micron down 3.7% and SanDisk off 4.6% premarket, while SK hynix's South Korean shares closed roughly 10% lower.

The weakness was hardly confined to U.S. storage names. Samsung Electronics (005930.KS) fell 7.4% in Seoul, SoftBank Group (9984.T) dropped 8.5% in Tokyo, and European chipmakers including ASML (ASML), STMicroelectronics (STM) and Infineon (IFX.DE) also declined, turning the episode into a global technology repricing rather than an isolated event.

CXMT's Denser Architecture Stirs Supply Fears

The immediate trigger is China's ChangXin Memory Technologies, which over the weekend announced progress on a "4F square" memory-cell architecture that packs more memory into a smaller space. The company reportedly plans a new server-memory product by the end of 2026.

That prospect challenges the perceived technological lead of Micron, Samsung and SK hynix at a moment when investors are already jittery about the durability of AI-driven demand and the capital required to fund it. Intel (INTC) and Broadcom (AVGO) executives have warned that access to financing could become a headwind to the AI buildout, even as computing-infrastructure demand continues to outstrip supply.

CXMT's global DRAM share has climbed to roughly 10% from about 4% a year earlier, according to an HSBC (HSBC) note cited in media reports — a trajectory that carries weight for pricing power even before it translates into meaningful shipments.

Not All Memory Is Created Equal

The crucial distinction, analysts say, is that CXMT's announcement concerns conventional DRAM server memory, not an established breakthrough in high-bandwidth memory used in AI accelerators — a segment where Korean suppliers retain a commanding position. Analysts quoted by CNBC note that CXMT still faces steep advanced-memory technology hurdles and has not demonstrated large-scale production of the new design.

"The market is reacting to a headline rather than a shipped product," said Vey-Sern Ling, senior equity adviser at UBP, describing investors as jittery and hunting for reasons to take profits in outperforming AI names. Rayliant strategist Phillip Wool called the reaction disproportionate to the near-term competitive threat.

The companies also span different parts of the supply chain. Micron and SK hynix face the most direct DRAM competition, while SanDisk's NAND flash business and the hard-drive operations of Western Digital and Seagate carry different exposures — making their simultaneous declines a sign of sentiment, not identical risk.

Strong Earnings, Falling Shares

The selloff illustrates how robust results and sliding prices can coexist when expectations run hot. Micron's fiscal fourth quarter, ended September 3, delivered revenue of $54.23 billion versus $11.32 billion a year earlier, with adjusted earnings per share of $33.42. SK hynix posted second-quarter revenue of KRW 79.32 trillion, up 257% year over year, at a 76% operating margin.

Western Digital's fiscal fourth-quarter revenue rose 44% to $3.75 billion, while Seagate reported $3.63 billion in revenue and record annual free cash flow of $3.1 billion. SanDisk's fiscal 2026 revenue reached $20.25 billion, up 175% year over year. SanDisk attributed roughly two-thirds of its latest sequential revenue gain to higher prices — underscoring how sensitive the group is to any shift in pricing dynamics.

It's worth noting that Western Digital separated its flash business into independent SanDisk in February 2025, so the two should not be read as one consolidated storage company.

Export Controls and the Road Ahead

U.S.-China technology restrictions form the competitive backdrop. CXMT has gained share despite limits on access to advanced chipmaking equipment, including ASML's extreme-ultraviolet lithography systems — raising questions about how effectively export controls preserve incumbents' advantages. Citi (C) analysts argued that even if Chinese-made memory faces barriers in the U.S., sales to data centers in regions such as Europe could indirectly pressure Micron.

For hard-drive makers, a separate supply concern is already in play: reports of Toshiba expanding production in the Philippines have unsettled Seagate and Western Digital, though Bernstein, Citi and Morgan Stanley (MS) have pushed back, arguing the expansion would not eliminate the HDD supply gap.

Near term, volatility is likely to persist as investors weigh CXMT's production timetable, upcoming earnings and the financing of AI infrastructure. Longer term, the key evidence is commercial production and customer adoption — not the announcement of a denser design.

Representatives for Micron, Western Digital, Seagate and SanDisk did not immediately respond to requests for comment.