Nvidia hit an all-time high but Seagate fell 11% in a day. They are both AI-related stocks, so why the split?
2026-10-03
Why did the same AI hardware split?
Nvidia hit an all-time high and SMH rose 2.07%. The same day Seagate fell about 11% and Western Digital about 7% (24/7 Wall St, 2026-10-02). The cause is not weaker AI demand but reports of rising supply.
According to Nikkei, Toshiba plans to spend about 60 billion yen (about $400 million) to double its HDD production capacity by fiscal 2027. The base is its plant in the Philippines (Benzinga, 2026-10-02).
The structure that splits winners and losers
When AI demand grows, two things happen at once.
- The scarce side gains pricing power. Nvidia GPUs and high-performance memory belong here. Reports of Micron's 88% consumer memory margin are one example.
- The easily replicated side sees margins break when new suppliers enter. HDDs were an oligopoly (Seagate, Western Digital, Toshiba), so a strong cycle meant higher prices. If Toshiba expands volume, the oligopoly's price discipline could weaken.
Share prices reflected this difference within a day.
| Segment | Supply constraint | Today's share price |
|---|---|---|
| GPUs, high-performance memory | Strong | Record high, SMH +2.07% |
| HDDs | New expansion becoming visible | STX about -11%, WDC about -7% |
Possibly an overreaction
Analysts pointed out limits to Toshiba's expansion. Unlike Seagate and Western Digital, Toshiba sources key components such as media and heads externally. These component suppliers would have to raise production sharply, and that supply could become a bottleneck (Benzinga, 2026-10-02). In other words, a doubling on paper is not a doubling of actual market supply.
What investors should do
- Before chasing individual storage stocks after the sharp drop, check whether component suppliers other than Toshiba have announced expansions. Without such an announcement, supply worries may be exaggerated; with one, the worries become real.
- On Reddit that day, mentions of WDC and STX surged, but the direction by stock was opposite. Do not judge direction by theme mention volume.
- Rather than investing directly in storage, holding the sector average through an ETF like SMH spreads out stock-specific shocks like this one. Marvell's October 6 event is the next checkpoint for AI hardware overall.