Seagate Vs. Western Digital: One Moved First on AI Storage Demand. The Other Is Playing It Safe.
Seagate and Western Digital both posted blockbuster quarters with nearly identical revenue guidance, yet one is shipping next-generation HAMR drives into hyperscale contracts right now while the other bets its future on timing the market perfectly.
Seagate Technology (NASDAQ:STX | STX Price Prediction) and Western Digital (NASDAQ:WDC) both closed fiscal 2026 with blockbuster quarters and guided fiscal Q1 2027 revenue to roughly $4.10 billion. Seagate is ramping HAMR-based Mozaic drives into hyperscale contracts today. Western Digital, now a pure-play HDD company after the Sandisk separation, is stretching ePMR further before its own HAMR product ships in 2027.
HAMR Ships Now for Seagate. Western Digital Squeezes ePMR Harder.
Seagate posted Q4 revenue of $3.63B, up 48.5% YoY, with non-GAAP EPS of $5.71 topping the $5.0932 consensus. Mozaic 4 drives, capable of up to 44 terabytes per drive, were shipping for revenue to 75% of the leading global cloud customers by March. CEO Dave Mosley told investors Seagate sees “durable long-term demand for mass capacity storage” anchored by its HAMR roadmap.
Western Digital’s quarter showed revenue of $3.75B, up 43.8% YoY, EPS of $3.56, and gross margin of 54.4%. Growth is driven by 40TB ePMR. The 44TB Hammer drive ships in the first half of calendar year 2027. CEO Irving Tan framed this as disciplined execution.
| Business Driver | Seagate | Western Digital |
| Lead HDD Technology | Mozaic HAMR shipping | 40TB ePMR + UltraSMR |
| Next Milestone | Mozaic 5, 50TB, late 2027 | 44TB Hammer, 1H 2027 |
| Cloud Customer Traction | 75% of top cloud customers on Mozaic | Cloud = 89% of Q4 revenue |
First Mover Versus Fast Follower
Seagate prioritizes areal density rather than increasing unit volumes, with nearline capacity almost fully allocated through calendar 2027. Western Digital is playing the patient hand. WD’s exabyte shipments grew 22% year over year in Q4, but cost-per-terabyte fell only approximately 8% year over year. Seagate’s HAMR economics are pulling costs faster.
| Lens | STX | WDC |
| Core Bet | First mover on HAMR | Extend ePMR runway |
| Key Vulnerability | Hyperscaler concentration, BIS settlement | Late to HAMR volume |
| Forward P/E | 23 | 22 |
Next Test: HAMR Qualification Speed
Watch whether Seagate can push 70% of nearline exabytes onto HAMR by fiscal 2027 without yield issues. For Western Digital, 44TB Hammer qualification with hyperscalers in early 2027 is critical. Also monitor pricing on LTAs extending to calendar years 2029, 2030 and 2031, where WD said commercial constructs are still being negotiated.
Why I Lean Toward Seagate After This Quarter
Seagate’s HAMR head start is real, gross margin expanded to 52.3% from 37.4% YoY, and free cash flow hit a record $3.1B for the year. Shares are up 325.27% over the past year, so valuation is not cheap. Western Digital trades at a P/E of 17 with a cleaner balance sheet, a profile often screened by value-oriented investors. Both names face risk if HAMR qualification slips or hyperscaler capex cools. Storage sits alongside power, cooling, and networking on the list of non-chipmaker AI beneficiaries we pulled together in a free report on seven of them.
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Alex Sirois is a financial writer with experience spanning both retail and institutional investing. He has written for InvestorPlace and held roles at BNY Mellon and Bernstein, giving him a perspective that bridges Main Street portfolios and Wall Street analysis.
Alex holds an MBA from George Washington University and has built his career across multiple industries, including e-commerce, education, and translation — a breadth of experience that informs how he breaks down complex financial topics for everyday investors. His writing is conversational, actionable, and grounded in long-term, buy-and-hold investing principles.
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