The S&P 500 Fell, but These 2 AI Memory Stocks Exploded Higher

Wall Street delivered a sharp split on September 4. The S&P 500 fell 0.4% after a stronger-than-expected jobs report lifted rate concerns, but Sandisk jumped 11.9% and Micron gained 6.1%. The divergence matters because it was not a broad risk-on move. The pattern was consistent with investors rotating toward memory and storage suppliers that help keep AI systems fed with data. That put Sandisk Corporation (NASDAQ: SNDK ) and Micron Technology, Inc. (NASDAQ: MU ) at the center of the session.

Sandisk offers the purer NAND and flash-storage argument. Its August results established data center as a key growth pillar, and management said it had signed five more new-business-model agreements since April. The bull case is that AI expands high-value enterprise storage demand while tighter supply supports pricing. The bear case is cyclicality: customer agreements cannot eliminate inventory swings, pricing reversals, or the execution risk that comes with a newly independent public company.

Professional ownership broadened before Friday's rally. Insider Monkey counted 128 hedge funds holding Sandisk Corporation (NASDAQ:SNDK) at June 30, up from 114 at March 31. Leopold Aschenbrenner's Situational Awareness LP disclosed 2,495,344 shares, about 119% more than the 1,140,119 shares reported in Q1. Those filings are quarter-end snapshots and do not show what the funds did during the September move.

Micron supplies both high-bandwidth memory and conventional DRAM and NAND. Its fiscal third-quarter revenue reached $41.46 billion, while Cloud Memory revenue rose to $13.77 billion and Core Data Center revenue to $11.52 billion. That operating leverage is the bull case. The counterargument is that extraordinary margins invite capacity additions, and today's scarcity economics may normalize faster than investors expect.

Hedge-fund breadth also rose for Micron Technology, Inc. (NASDAQ:MU), to 184 funds in Q2 from 154 in Q1. Cliff Asness's AQR Capital Management reported 3,833,728 shares, about 15% fewer than the 4,523,415 shares disclosed in Q1. The August 14 exchange-reported settlement recorded 7,676,558 SNDK shares sold short, about 8.24% of the estimated public float, equal to roughly 0.5 day of average trading volume. That snapshot predates the rally and cannot identify motive.

The session supports a real thesis: AI demand is spreading from accelerators into the memory hierarchy. Sandisk has more focused upside but greater company-specific and NAND-cycle risk. Micron has broader product exposure and exceptionally strong disclosed margins, yet it also carries more expectations. The next proof points are pricing, data-center mix, and whether customer commitments survive the next supply response. Both can benefit from demand while suffering very different supply and execution failures, a distinction Friday's prices cannot resolve. Quarterly contract volumes should reveal which thesis is gaining ground.