SanDisk and Western Digital shares jump 6% as AI storage demand drives record highs, with SanDisk up 724% year-to-date on strong datacenter revenue.

What happened: SanDisk (NASDAQ: SNDK) and Western Digital (NASDAQ: WDC) both rose 6% on Friday, with SNDK trading near $1,989 and WDC near $561. SanDisk has surged 724% year-to-date and 4,638% over the past 12 months, while Western Digital has gained 224% year-to-date and 902% over the past year, riding demand for AI infrastructure storage.

Why it matters: SanDisk's Q3 FY2026 results (reported April 30) showed revenue of $5.95 billion（約9500億円）, up 251% year-over-year, with datacenter segment revenue jumping 645% year-over-year to $1.47 billion（約2400億円）. CEO David Goeckeler called the quarter "a fundamental inflection point for SanDisk" as the company shifts toward datacenter customers under multi-year supply contracts. Western Digital's Q3 FY2026 report delivered revenue of $3.34 billion（約5300億円）, up 46% year-over-year, with non-GAAP gross margin clearing 50% for the first time in recent memory as AI workloads tightened hard-disk drive supply.

What to watch: SanDisk guided Q4 FY2026 revenue to $7.75 billion（約1.2兆円） to $8.25 billion（約1.3兆円） and non-GAAP EPS of $30 to $33. Western Digital guided Q4 FY2026 revenue to roughly $3.65 billion（約5800億円） and non-GAAP EPS of $3.25, plus or minus $0.15. The market is debating whether this represents the early innings of a multi-year AI memory supercycle or a late-stage rally vulnerable to sharp reversal; incoming NAND and hard-disk drive pricing data could test the rally.