Memory stocks surge over 10% as AI demand fears ease

US memory and storage stocks staged their strongest single-day rally in months on July 21, reversing a selloff that had erased more than a fifth of the sector's value.

Micron Technology rose 10.17 percent, SanDisk gained 11.86 percent, Western Digital climbed 12.67 percent, Seagate Technology added 10.42 percent, SK Hynix advanced 11.18 percent and Kioxia Holdings surged 13.78 percent, as investors returned to the sector after weeks of heavy losses.

"The selloff overshot fundamentals — HBM supply remains tight through 2027 and enterprise SSD pricing is still climbing," said C.J. Muse, semiconductor analyst at Cantor Fitzgerald. "This is a repositioning trade ahead of what we expect to be a strong second half."

The rebound follows a punishing stretch. Micron had fallen about 24 percent from its June peak, Western Digital dropped 35 percent and SanDisk lost 36 percent, according to market data. The selloff was amplified by margin-call liquidations in South Korea, where retail investors had loaded up on leveraged single-stock ETFs tied to Samsung Electronics and SK Hynix, and by hedge funds dumping US tech stocks at a record pace, per Goldman Sachs' prime brokerage data.

The sector's recovery carries weight beyond the stocks themselves. Memory chips serve as a bellwether for AI infrastructure spending: HBM — the high-bandwidth memory stacked inside Nvidia's AI accelerators — remains supply-constrained, and enterprise SSD prices continue to rise. If the rally holds, it could signal that the worst of the AI trade's de-leveraging is behind the market.

A Correction, Not a Reckoning

The prior selloff was driven more by positioning than by deteriorating fundamentals. South Korean retail investors had poured a net 14 trillion won (US$9.4 billion) into single-stock leveraged ETFs since their May launch, per LSEG data, with the KODEX SK Hynix Single Stock Leverage ETF losing about 70 percent from its June record. The Bank of Korea flagged record retail leverage as a risk, warning it could magnify volatility. In the US, short interest against the S&P 500 hit a record 3.79 percent of free float, with the largest dollar-value shorts concentrated in the Magnificent Seven and memory chipmakers, S3 Partners data shows.

HBM Tightness Remains the Anchor

What ultimately drew buyers back is the supply-demand math. HBM3E — the latest generation of high-bandwidth memory — remains in short supply, with SK Hynix and Micron sold out through 2027, according to company disclosures. Nvidia, the primary customer, consumes the vast majority of HBM output for its H200 and new Blackwell accelerators. Enterprise SSD prices, meanwhile, continue to climb as data center operators race to build out AI storage capacity. SanDisk and Western Digital, the dominant NAND flash suppliers, have benefited from pricing power that shows no sign of easing.

For investors, the question is whether this rally marks a durable recovery or a dead-cat bounce. Micron trades at about five times estimated forward earnings, a steep discount to its historical average, suggesting the market is pricing in a sharp downturn that has not yet materialized. "If HBM pricing holds and enterprise demand stays strong, these stocks have significant upside from here," Muse said. "The risk is that the macro environment deteriorates and data center CapEx gets cut — but we're not seeing that yet."

This article is for informational purposes only and does not constitute investment advice.