Micron stock falls as Chinese rival CXMT advances denser memory chip

Micron $MU Technology stock fell Monday after China's ChangXin Memory Technologies announced progress on a new chip design that can pack more data onto a single chip. Micron stock was down about 3% to $998.15 in Monday trading, putting it on track for a third consecutive losing session.

According to the South China Morning Post, which cited a company statement, CXMT President Cao Kanyu told attendees at a Shanghai industry event over the weekend that the company intends to launch a new server memory product before the end of 2026. The so-called 4F square design places each memory cell within an area equal to four times the square of F — the minimum line width of a semiconductor — enabling a greater number of cells to fit on the same chip.

The announcement rippled through the broader memory sector. Shares of SK Hynix and Samsung Electronics, both of which have been exploring the same 4F square architecture, also declined. SK Hynix American depositary receipts shed roughly 3.6%, and Samsung Electronics finished the session down 4.4%. Sandisk tumbled 5.7%, with hard disk-drive manufacturers Seagate $STX and Western Digital $WDC posting losses of 3.4% and 2.3%.

Investors have monitored CXMT as a potential disruptor to the memory market. When CXMT made its trading debut in July, its shares rocketed 466%, lifting the company's market capitalization to just under $500 billion, according to Barron's. As of Monday’s close, CXMT remained China’s largest company by total valuation, ahead of Tencent and state-owned banks China Construction Bank and Agricultural Bank of China, according to Barron’s.

Micron stock had been among the strongest performers in the market this year heading into Monday. Memory chip makers have benefited from surging demand tied to AI data center construction, which has kept supply tight and driven up prices for high-capacity memory. Micron stock was up 261% for the year through Friday's close.

Analyst Jim Cramer argued in August that memory manufacturers had changed their behavior by locking in revenue through extended customer contracts rather than expanding production to chase volume — a shift he said made the sector's rally more durable than past cycles. He flagged a surge in new manufacturing capacity, including from Samsung, as among the key risks that could end the rally.