Why Micron, SanDisk and SK Hynix are suddenly at the centre of the AI selloff

Micron, SanDisk and SK Hynix are sitting at the sharp end of Monday’s AI sell-off as investors question one of the assumptions that made memory stocks the biggest winners of the infrastructure boom.

Micron and SanDisk fell more than 5% in US premarket trading, while SK Hynix plunged 7.4%.

The declines followed weekend calls from Anthropic CEO Dario Amodei and other AI leaders to slow frontier-model development over safety concerns.

Memory became one of AI’s most leveraged trades

Training and running advanced AI models requires far more than GPUs.

HBM feeds accelerators, conventional DRAM supports servers and enterprise NAND provides the storage needed for large inference workloads.

That demand transformed memory from a cyclical commodity business into one of AI infrastructure’s most valuable bottlenecks.

Susquehanna analyst Mehdi Hosseini told MarketWatch that memory has become the “king” of the semiconductor industry and argued that “its reign is here to stay”.

He estimates memory now represents roughly 50% to 55% of semiconductor-industry revenue, compared with a historical range of 20% to 30%.

AI data-centre investment has been a reason the industry is approaching $1.5 trillion in annual revenue.

That explains Monday’s reaction, as the stocks that became concentrated bets on relentless AI infrastructure spending are naturally among the first to be repriced when investors question that spending trajectory.

The sell-off is pricing a slowdown that has not happened

No major hyperscaler has announced a material reduction in AI capital expenditure, and frontier laboratories have not said they plan to stop buying compute.

Investors are instead pricing a new risk to future growth.

“Fundamentally, the question that would come up is whether increased AI safety means slower and lower capex spending,” Barclays strategist Emmanuel Cau told the Financial Times.

The issue matters particularly for Micron and SK Hynix because HBM demand is tied closely to accelerator deployments.

SanDisk has a similar sensitivity through NAND. At Goldman Sachs’ technology conference last week, management said data-centre demand had grown to more than half of the NAND market, calling the shift a watershed moment for the industry.

The awkward problem for bears is that memory is still scarce

The bearish argument runs into an uncomfortable reality that the memory market remains severely constrained.

KB Securities estimates finished memory inventories at Samsung Electronics and SK Hynix have fallen below 10 days of supply.

“As of the third quarter, memory inventories at Samsung Electronics and SK hynix have fallen to less than 10 days,” research head Kim Dong-won told Seoul Economic Daily, warning that sellable volumes could become “absolutely insufficient”.

KB expects 2027 DRAM and NAND bit-demand growth to exceed supply growth by more than 10 percentage points as HBM4, server DDR5 and enterprise SSD demand rise together.

Bernstein also reiterated Buy ratings on Micron and SanDisk this month, forecasting conventional DRAM and NAND contract prices could rise nearly 20% quarter-on-quarter in the third quarter.

That leaves memory stocks caught between two realities.

AI safety concerns have introduced a genuine risk to future infrastructure spending, but current supplies remain tight, prices are still rising and inventories are unusually low.