Seagate and Toshiba are competing to acquire TDK's HDD magnetic head business, Bloomberg reported on October 6, 2026, citing people familiar with the matter. TDK said the same day that the report was not announced by the company and that nothing has been decided at this point. It is unclear how the talks will end, but four days earlier Toshiba had announced the first shipments from an expanded production line for data center HDDs. For HDD makers ramping up output, a key question is how to secure a supply of the magnetic heads that read and write data on the disk, and how to maintain a joint development framework for next-generation products.
What it means to acquire an independent head maker
At its 2024 earnings briefing, TDK described itself as the "only independent manufacturer" of HDD heads, and said its heat-assisted magnetic recording (HAMR) prototypes were not aimed at just one particular customer. Here, "independent" means not belonging to a finished-HDD maker and providing technology and components to multiple customers. It does not mean that HDD makers cannot manufacture heads themselves.
Indeed, Seagate states in its fiscal 2026 annual report that it designs and manufactures its own read/write heads and magnetic recording media. Vertical integration, which links component development, finished-product design and mass production within the company, is a strength that lets it switch technologies quickly.
Still, Seagate cites the risk of depending on a single supplier or a small number of suppliers for some components, including externally sourced heads. Even with its own manufacturing facilities, a company cannot fully cut itself off from outside component procurement.
Bloomberg, meanwhile, reports that Toshiba sources all of its HDD heads from TDK. The parties to the talks have not formally announced this sourcing ratio, but it shows that an acquisition would mean different things to the two companies. For Seagate, it would secure an external source that complements in-house production; for Toshiba, it would preserve the supply of a key component underpinning its own HDD production.
If an HDD maker itself acquired TDK's head business, a competitor that had been buying components from the same independent manufacturer could end up with that supplier under its roof.
In its April 2026 explanation, TDK also mentioned orders from HDD makers that produce heads in-house. The independent head maker does not support only customers that rely mainly on outside sourcing. Its ability to meet demand from manufacturers that make their own heads also adds to the value of the business.
Toshiba's "roughly double" refers to storage capacity, not unit volume
On October 2, Toshiba Electronic Devices & Storage announced the first shipment of nearline HDDs from an expanded production line at its Laguna Technopark plant in the Philippines. Nearline HDDs are high-capacity drives used to store large volumes of data in data centers and similar facilities. The plant, which had mainly made HDDs for PCs, has expanded production of data center products.
The target announced at the same time was to roughly double annual production capacity at Toshiba Information Equipment (Philippines) as a whole in fiscal 2027 compared with fiscal 2025. However, the basis used in the official announcement is "storage capacity". Reading it as a plan to double the number of HDDs produced would lead to a misjudgment of the volume of parts required and the impact on the market.
The total storage capacity that can be produced in a year is determined, roughly, by the number of HDDs and the average capacity per drive. Beyond expanding assembly capacity, total capacity can also be raised by increasing the capacity per drive even with the same number of units.
TDK also explained in April 2026 that HDD makers were trying to meet demand by raising the storage capacity per drive rather than increasing unit volumes significantly. Both expanding production lines and increasing recording density are ways to increase the total capacity that can be supplied.
This difference also matters when thinking about demand for magnetic heads. Even if overall HDD production capacity doubles, the number of heads needed will not necessarily rise by the same factor. Raising capacity per drive allows supply capacity to grow while limiting the increase in part counts, but it also makes the ability to stably mass-produce next-generation heads for high-density recording more important.
In looking at Toshiba's plan, it is necessary to separate how much each of two factors, stronger assembly lines and the shift to higher-capacity HDDs, contributes to the expansion of total storage capacity.
The first shipment is something that has already happened, but "roughly double" is a target for fiscal 2027. It does not mean that production capacity has already doubled.
TDK and Toshiba's joint development behind HAMR
The relationship between Toshiba and TDK goes beyond the delivery of magnetic heads. They have also cooperated in developing next-generation recording technologies.
In May 2024, Toshiba announced that it had demonstrated HDD capacities exceeding 30TB with each of HAMR and microwave-assisted magnetic recording (MAMR). The results came from joint development with TDK, which develops magnetic heads, and Resonac, which develops magnetic recording media for disks.
HAMR locally heats the disk with near-field light, enabling higher-density magnetic recording. MAMR uses microwaves to improve recording performance.
The 2024 demonstration conditions announced by Toshiba differed as follows.
| Recording technology | Demonstrated capacity | Number of disks | Recording method and other conditions |
|---|---|---|---|
| HAMR | 32TB | 10 | Used SMR |
| MAMR | 31TB | 11 | Used SMR and improved signal processing |
SMR is a method that raises capacity by partially overlapping adjacent recording tracks. This table does not compare mass-produced products; both are results of technology demonstrations at the time.
The plan for HAMR prototype samples that Toshiba presented in the same announcement aimed for 28 to 30TB with conventional magnetic recording (CMR). Numbers cannot be compared without aligning the maximum capacity demonstrated, the recording method used and the stage of productization.
The fact that three companies responsible for the head, the recording media and the finished HDD cooperated to demonstrate the technology is also important when considering the impact if the buyer of TDK's head business changes.
Even if a contract is signed to continue supplying heads for existing products, joint development of next-generation technology and access to that technology will not necessarily continue on the same terms as before. Conversely, reports of acquisition talks do not mean that current joint development will stop immediately.
For Toshiba, both stable procurement of the required quantity of heads and continued development cooperation for the shift to next recording methods such as HAMR are important.
TDK's results are improving, so the sale report cannot be explained by decline alone
In the first quarter of the fiscal year ending March 2027, TDK's magnetic application products segment posted sales of ¥81.6 billion and operating profit of ¥9.6 billion. A simple calculation from the published figures gives an operating margin of about 11.8%. Sales rose 49.6% from a year earlier and operating profit rose 51.8%.
TDK explained that the HDD market was solid on demand for AI data centers, and said HDD head sales volume rose 36% year on year and suspensions rose 31%.
The calculation uses figures for the same segment and period in the company's first-quarter earnings explanation. However, the magnetic application products segment includes not only HDD heads but also the suspensions that support the heads and magnets. The figure of about 11.8% is an approximation derived from published values in units of ¥100 million, and is not the profit margin of the head business alone, which is the subject of the acquisition report. This number alone cannot be used to judge the value of the business that may be sold.
The improvement in results is not limited to a single quarter. In the fiscal year ended March 2026, the magnetic application products segment had sales of ¥262.9 billion and operating profit of ¥27.0 billion, with sales up 17.6% from the previous year and operating profit up about eight-fold. Head sales volume for nearline HDDs rose about 14% and suspensions about 35%.
At least judging from the recent figures, it does not fit the facts to describe this as a business shrinking because it has lost demand.
At the same time, launching next-generation technology will continue to require investment. In April 2026, TDK explained that it would expand production capacity for heads and suspensions and would also invest in HAMR equipment for heads. It also set out a policy of mass-producing HAMR about "two years" from that point, raising the share of high-value-added products and improving the profitability of the head business.
This is a plan for the future and does not mean that HAMR mass production has already been achieved.
The sale negotiations reported by Bloomberg need to be considered separately from the investment and growth plans TDK has published so far. What TDK said on October 6 was that it is strengthening business portfolio management to increase corporate value. It has not announced that it has decided to sell the head business, nor that it has stopped investing in HAMR.
If a deal does take shape, then in addition to capturing the currently growing HDD demand, who bears the capital investment needed for next-generation technology will also shape the future of the business.
Conditions for sustaining supply, seen in past HDD consolidation
The HDD industry has a precedent in which simply transferring factories and equipment was not enough to preserve competition.
In 2012, the US Federal Trade Commission (FTC) raised concerns about reduced competition in the desktop PC HDD market over Western Digital's acquisition of Hitachi-affiliated HGST. As a remedy, it required not only the transfer to Toshiba of the assets needed for manufacturing and sales, but also licensing of intellectual property and access to the personnel responsible for R&D and manufacturing.
Measures to keep production from stopping during the transfer were also included. Western Digital would supply the necessary components and carry out contract manufacturing of HDDs until Toshiba could manufacture them itself. In May 2013, the FTC approved a modified final order adjusting the transfer schedule and other matters.
To keep the business alive as a competitor, it was necessary to bridge to a state in which it could actually keep making products, not merely hold the equipment.
That said, that was a consolidation between finished-HDD makers, and the structure of the deal differs from the acquisition of a magnetic head supplier now being reported. It provides no basis for predicting that the same conditions would be required or that the acquisition would not be allowed.
Even so, the past case in which equipment, technology and component supply during the transition period were designed separately offers a reference for looking at deal terms that may be announced.
In this case too, the impact will vary greatly depending on how many units will be supplied to existing customers and for how long, who can take part in joint development of next-generation heads, and who will bear the investment in HAMR equipment.
These terms have not yet been made public, and this is not a story in which Toshiba's head supply would stop immediately once a buyer is decided. If the quantities of parts supporting Toshiba's production increase can be secured while the development and investment needed for next-generation products continue, it may be possible to expand data center supply capacity while preserving competition among finished-HDD makers.