Did SanDisk's Jul 2 supply-glut selloff break it from its memory-chip peers?
Treated: SNDK. Donors: WDC, MU, STX, NTAP (memory/storage peers also riding the same 2026 AI-driven DRAM/NAND shortage supercycle narrative). Hand-picked, not algorithmic. Treatment date is 2026-07-02, the day SNDK fell about 14% intraday (11% close to close per same-day reporting) on Samsung/SK Hynix new-supply and AI-capex-peak fears spreading across the whole memory complex. This was the largest of several repeated 'supply glut fear' selloffs in the group through Jul-Sep 2026 (further echoes hit on 7/13, 7/29, 8/6, 8/18, and 9/10); 7/2 was chosen as the single cleanest, largest-magnitude catalyst date rather than trying to model the whole multi-month sequence at once. Tests whether SNDK's drop was company-specific or part of a shared sector re-pricing that should also show up in WDC/MU/STX/NTAP, against a backdrop where the underlying shortage thesis (DRAM/NAND contract prices up 58-75% QoQ in Q2 2026) stayed intact through the same window.
Actual vs. synthetic counterfactual
ActualSynthetic (counterfactual)
Fit quality
Fit-window RMSE206.0415
RMSE ÷ fit-window std dev1.02×
Fit-window days125
Confound-window mean gapn/a (fit-end = treatment date)
Post-period mean gap+262.15
Placebo test: same method run on every unit, treated one highlighted
Unit
Mean post-period gap
Max abs. gap
SNDK (treated)
+262.15%
378.72%
NTAP
-123.33%
158.22%
WDC
-34.49%
76.35%
STX
+16.46%
43.25%
MU
+7.50%
33.12%
Verdict
Do not trust the gap below. The fit-window RMSE is 1.02× this unit's own fit-window standard deviation: the donor pool literally cannot reconstruct SNDK's pre-period path at all, which usually means the donor pool is the wrong choice for this unit (e.g. SNDK moved for reasons entirely disconnected from the donors' own drivers), not that a real effect was found. Pick a different/better-correlated donor pool before drawing any conclusion from this run.