Memory chip makers Sandisk and Micron have soared on AI demand, but Micron's broader exposure to both DRAM and NAND leaves it better positioned than Sandisk's narrower flash focus.

What happened: Sandisk's fiscal Q3 revenue jumped 251% year-over-year to $5.95 billion（約9500億円）, with data center revenue climbing 233% sequentially, while Micron posted fiscal Q2 revenue of $23.86 billion（約3.8兆円）—nearly triple the year-ago figure—and is guiding for about $33.5 billion（約5.4兆円） in fiscal Q3. Both companies have surged because AI infrastructure needs more memory and storage than supply can provide.

Why it matters: Sandisk has locked in demand through five multiyear supply agreements covering more than a third of its fiscal 2027 output and backed by over $11 billion（約1.8兆円） in enforceable financial guarantees, removing some cyclical risk. Micron, meanwhile, makes HBM (dense stacked chips that pair with AI accelerators), which it says is already sold out for 2026, and has begun shipping its newest HBM for Nvidia's next-generation Vera Rubin platform. Both are returning cash to shareholders—Sandisk via a $6 billion（約9600億円） buyback and carries no debt—while Micron funds a major build-out spending more than $25 billion（約4兆円） on new plants and equipment this fiscal year.

What to watch: On forward valuation multiples (comparing price to analysts' consensus earnings forecasts over the next 12 months), Sandisk and Micron trade at roughly 11× and 10× respectively, making them priced similarly by growth prospects. However, Sandisk's business is narrower than Micron's, leaving it with greater downside risk if the AI memory cycle turns.