Micron Technology fell about 4% on 12 October, and Samsung and SK hynix dropped more than 7% in Seoul the next day. The trigger was a claim from CXMT, China’s largest DRAM maker. At a Shanghai chip conference on 9 and 10 October, its president said the company has a 4F² memory design and will launch server DDR5 modules on it before the end of 2026. A spokesperson later confirmed them.

4F² is a denser way to lay out memory cells, about a third smaller than today’s 6F² standard. Samsung’s own target for mass production is around 2028. CXMT says it uses older lithography tools, working around US limits on advanced equipment. It disclosed no specifications, yields or customers.

The updated report keeps Micron at Buy but now treats CXMT as a high-impact risk.

Reasons to worry

1. CXMT is growing fast. Counterpoint puts its DRAM revenue share at about 10% in the second quarter of 2026, up from 4% a year earlier.
2. Server memory is Micron’s core. Its two data-centre units made up 63% of fiscal fourth-quarter revenue.
3. If CXMT ships at scale in 2027 and 2028, displaced supply could push server DRAM prices down. The report’s own estimate puts that hit at about 7% of fiscal 2028 earnings, and the bear case falls to $709 from $749.

Reasons the sell-off looks overdone

1. A claim is not a product. CXMT’s DDR5 arrived about two years later than it had targeted, and Morningstar expects a long gap before 4F² chips reach viable yields. The first modules may not use it fully.
2. CXMT is far behind in high-bandwidth memory, the AI product where Micron earns its best margins.
3. US access is limited. US federal purchases of products containing CXMT chips are barred from 23 December 2027.
4. Micron’s fiscal 2027 is largely contracted, with $32bn of customer commitments.

What changed in the numbers

Fair value falls to $1,146 from $1,161, about 16% above the $989.04 close on 12 October. The Competitive Advantage score drops to 6 from 7. The buy range narrows to $950 to $1,000, the first target moves to $1,150, and the $860 cut-loss holds. The scenario weights hold, since there is no hard evidence yet. If 10 points of probability shifted from the bull case to the bear case, fair value would drop to about $1,051 and the Buy would be in question.

Watch the end of 2026. A named server customer or disclosed yields would make the threat real. A late or China-only launch would ease it.

The CXMT sizing, the scenario table and the updated trade levels are in the complete Micron Technology (MU) report on our Reports page.