Toshiba's $380M HDD Expansion Triggers 10% Plunge in Seagate, Western Digital

Key points

• Seagate and Western Digital shares fell about 10% on Friday, October 2, 2026, following reports of Toshiba's expansion plans.
• Toshiba plans to invest approximately $380 million (or ¥60 billion) in a Philippines facility to double its HDD capacity by fiscal 2027.
• The expansion aims to increase Toshiba's market share from 10% to 30%, challenging the dominance of Seagate and Western Digital.
• The move threatens the supply shortage that has boosted pricing power and record profits for the two US firms.
• Analysts note that Toshiba relies on external suppliers for key components, which may limit the speed and scale of its capacity expansion.

Background

Seagate and Western Digital have been among the top performers in the S&P 500 since mid-2025, driven by AI-driven demand for data storage. Seagate shares had gained roughly 240% and Western Digital about 170% in 2026 before the recent decline. In August 2026, storage stocks had already pulled back due to rising interest rates, but the AI infrastructure fundamentals remained strong. This latest drop follows a period of significant gains, making the stocks vulnerable to profit-taking on signs of increased competition.

How outlets are covering it

Barron's and Investing.com both report the 10% drop in Seagate and Western Digital shares, but differ slightly on the exact figures: Investing.com notes Seagate fell 11% and Western Digital 7%, while Barron's cites a 10% drop for both. Barron's highlights Mizuho analyst Jordan Klein's view that Toshiba's target is unrealistic and that new capacity would not significantly affect deal negotiations until 2028. Investing.com cites Citi analyst Asiya Merchant, who argues the market may be overstating the impact because Toshiba relies on outside suppliers for key components like media and heads, which would need to significantly increase production to support Toshiba's expansion. Both outlets agree that the move threatens the supply shortage that has boosted pricing power for Seagate and Western Digital, but analysts suggest the impact may be limited in the near term.

Why it matters

The story highlights the competitive dynamics in the hard disk drive market, which is dominated by three companies: Seagate, Western Digital, and Toshiba. Toshiba's expansion could ease the supply shortage that has driven record profits for the two US incumbents, potentially pressuring market share and pricing. However, the impact may be limited in the near term due to supply chain constraints and timing delays. The move also signals increased competition in the AI data-center storage market, which is a key growth area for the industry.

What to watch

Investors will watch for further developments in Toshiba's expansion plans and any impact on Seagate and Western Digital's market share and pricing. Analysts will monitor the supply chain constraints that may limit Toshiba's ability to double its capacity by fiscal 2027. The story may also influence the broader AI infrastructure narrative, as data-center operators welcome more capacity but are concerned about pricing power.