Seagate Closed at $805.63, Down 9.18%, and Western Digital…

Tuesday’s drop in the hard-drive pair was not a second printing of Friday’s Toshiba-capacity selloff, and it was not one move shared by two identical stocks. Seagate Technology closed the Tuesday 6 October 2026 regular session at $805.63, down $81.46, or 9.18 percent, from Monday’s $887.09 close. Western Digital closed the same session at $411.04, down $30.60, or 6.93 percent, from Monday’s $441.64. Those are Nasdaq’s official closes, not a premarket print. The fresh item in front of that tape was a Bloomberg report, first timestamped 3:53 a.m. UTC on 6 October and updated at 10:37 a.m. UTC, that Seagate and Toshiba are in a contest for TDK’s magnetic-heads business, in a deal people familiar with the matter put at as much as several billion dollars. The closes used here are Tuesday’s official prints. Neither company filed an 8-K that day. The overnight gaps were almost the same. The cash session was not.

What moved, and why the obvious reading is incomplete

The obvious reading is that Tuesday was Friday again. It was not. On Friday 2 October, Nasdaq’s closes show Seagate at $848.99 and Western Digital at $415.29, each about 10.2 percent below Thursday’s $945.57 and $462.56. FinanceFeeds has already filed that Friday capacity report. The item that day, as Yahoo Finance reported it on 2 October, was a Nikkei account that Toshiba plans to spend about ¥60 billion, or $380 million, to double hard-disk output by fiscal 2027. Monday 5 October was a bounce: Seagate rose to $887.09 and Western Digital to $441.64, gains of 4.49 percent and 6.34 percent calculated from those Friday closes.

Tuesday’s new report was about a component, not about another capacity headline. Bloomberg’s 6 October story said Toshiba opened talks with TDK in the spring and that Seagate followed with a higher offer in the summer. The people cited asked not to be identified because the discussions are private. Bloomberg’s own account on X, posted at 4:05 a.m. UTC on 6 October, said the two companies “are locked in a contest for TDK’s magnetic-heads business for hard-disk drives in a deal that could be worth several billion dollars.” That post is here. It was public hours before the US cash open. It is a report of private talks. It is not a signed deal, and it is not an 8-K.

Friday’s drops matched, at 10.21 percent and 10.22 percent. Tuesday’s did not. Seagate’s 9.18 percent decline was 2.25 points larger than Western Digital’s 6.93 percent. From Friday’s close, Seagate finished 5.11 percent lower and Western Digital only 1.02 percent lower.

The session was also not a broad Nasdaq liquidation. The Nasdaq Composite closed Tuesday at 27,599.79, up 122.48 points, or 0.45 percent, on Nasdaq’s index quote. The same cash session is the one FinanceFeeds has already covered for Marvell’s investor day and for Ciena. Hard drives sold off while that networking tape was a different story.

Bloomberg named Seagate, not Western Digital, as the higher bidder. The gaps were almost the same: Seagate opened at $857.12, down 3.38 percent from Monday, and Western Digital opened at $426.60, down 3.41 percent. The cash session was not the same. Seagate closed down 6.01 percent from the open, after a $798.62 to $863.50 range. Western Digital closed down 3.65 percent from the open, after a $406.81 to $430.33 range. That fits a buyer-versus-customer reading. It is not proof. Neither company confirmed a bid.

What the company, the customer, or the analyst actually said or did

Silence is part of the record. SEC submissions for Seagate (CIK 0001137789) and Western Digital (CIK 0000106040) show no Form 8-K on 6 October 2026. Western Digital’s Monday filings were a proxy and an annual report, not a release about TDK.

What the companies last said on the record was about demand, not about buying TDK. In the release dated 29 July 2026, Dave Mosley, Seagate’s chair and chief executive, said: “Seagate’s strong fourth quarter exceeded our expectations for revenue and non-GAAP EPS, capping a fiscal 2026 in which we grew annual revenue 34%, delivered record profitability, and generated a record $3.1 billion in free cash flow. Our performance is being driven by robust cloud data center demand and disciplined execution, and we see the momentum continuing in 2027.” That sentence is in the 28 July 8-K exhibit, and it was not updated on Tuesday.

Irving Tan, chief executive of Western Digital, said in the 5 August 2026 release: “WD concluded fiscal year 2026 with strong performance. In our fiscal fourth quarter, revenue increased 44% year over year, gross and operating margins expanded, and earnings per share more than doubled.” Kris Sennesael, chief financial officer, gave the outlook in the same exhibit: “For our fiscal first quarter of 2027, at the midpoint of the ranges provided in the table below, we expect revenue of $4.1 billion, non-GAAP gross margin of 55.5%, and non-GAAP EPS of $4.00.” The same release says the flash business was separated into Sandisk on 21 February 2025. Sandisk is a different company and is not this tape. The sentences are in the 5 August exhibit.

The named analyst line on the capacity scare is from Friday. Yahoo Finance on 2 October, at 12:45 p.m. EDT, paraphrased Citi analyst Asiya Merchant: Toshiba’s plan may not loosen supply unless outside makers of media and heads add capacity too. That is about the $380 million budget. It is not a comment on a TDK bid.

Invezz, dated 6 October, reported that a Toshiba spokesperson said Bloomberg’s account was inconsistent with the company’s understanding and with Japan Industrial Partners’, and it printed intraday prices, $808.08 and $413.16, that are not the closes. Heise, at 8:15 a.m. CEST on Wednesday 7 October, reported that a spokesperson said no meeting had taken place and that Seagate and TDK declined to comment. Those Wednesday words do not rewrite Tuesday’s close.

William D. Mosley sold 30,000 shares on 1 October, disclosed in two Forms 4 filed on 2 October: 18,998 shares for $17,376,987.69 and 11,002 shares for $10,293,464.47, together $27,670,452.16. Both say the trades followed a Rule 10b5-1 plan adopted on 18 February 2026. He also exercised 14,000 options at $46.23. A “$17.4 million” headline is the first form only. A February plan did not cause a 6 October decline.

The tape and the filings

Friday and Monday percent changes below are calculated from the prior Nasdaq close. Tuesday’s percent changes are the ones Nasdaq reported, and they match that arithmetic. Volume is Nasdaq’s figure.

Session	Seagate close	Seagate change	Seagate volume	Western Digital close	Western Digital change	Western Digital volume
Thu 1 Oct 2026	$945.57		2,485,101	$462.56		6,167,322
Fri 2 Oct 2026	$848.99	−10.21%	13,577,250	$415.29	−10.22%	24,768,460
Mon 5 Oct 2026	$887.09	+4.49%	5,594,908	$441.64	+6.34%	11,300,420
Tue 6 Oct 2026	$805.63	−9.18%	7,282,772	$411.04	−6.93%	14,044,090

From Thursday’s close to Tuesday’s, Seagate fell 14.80 percent and Western Digital 11.14 percent. The split opened after Friday’s matched drop. Tuesday’s volume was about 54 percent of Friday’s at Seagate and 57 percent at Western Digital. Both closes sat near the low, $7.01 above Seagate’s $798.62 low and $4.23 above Western Digital’s $406.81 low.

Nasdaq’s quote page, fetched Wednesday morning before the US open, put Seagate’s 52-week range at $209.00 to $1,145.00 and Western Digital’s at $112.52 to $799.87. Tuesday’s closes sit 29.6 percent and 48.6 percent under those highs. The page did not date either high.

StockAnalysis pages fetched 7 October, marked to Tuesday’s closes, put the equities at about $183.19 billion and $153.86 billion, roughly $337 billion together. The multiple is not one number. Seagate’s fiscal 2026 GAAP diluted earnings were $13.90 and non-GAAP earnings were $15.58. At $805.63 the GAAP line is the 57.96 multiple StockAnalysis showed, and the non-GAAP line is about 51.7 times. Western Digital’s GAAP diluted earnings were $24.28 and its non-GAAP earnings were $10.22, against non-GAAP net income of $3.883 billion rather than the $9.298 billion GAAP figure. The 16.93 trailing multiple is the GAAP line. At $411.04, $10.22 is about 40.2 times. The company guides only on non-GAAP, and the quarter splits the same way: GAAP diluted earnings of $8.21 versus non-GAAP of $3.56.

The constraint that sits under the headline

The constraint is the recording head, not the press release. TrendForce, writing on 6 October and attributing the industrial detail to Bloomberg, said TDK is the only independent supplier of magnetic heads and that it supplies Seagate, Toshiba and Western Digital. Seagate and Western Digital make heads in-house and go to TDK when demand spikes. Toshiba, on that account, relies entirely on TDK, including for the heat-assisted drives it would need to close the gap. Heise’s Wednesday piece adds that Toshiba also buys TDK heads for drives using microwave technology above 30 terabytes.

That is why a capacity headline and a heads headline are not the same story. The Nikkei item is a $380 million plan to double Toshiba’s own output by fiscal 2027. Citi’s Asiya Merchant, as paraphrased on 2 October, said the plan may not reach the market unless outside suppliers of media and heads expand too. TrendForce’s 2026 share projection is a concentrated industry: Western Digital 48 percent, Seagate 42 percent, Toshiba 10 percent. Doubling a 10 percent share, if the components exist, is a pricing event. Announcing a budget without the heads is a press release. Tuesday’s report, if Bloomberg’s sources are right, is an attempt to buy the independent head line rather than wait for it.

The dollar sizes do not line up. Several billion dollars, the figure Bloomberg’s sources gave for a TDK deal, is an order of magnitude above the $380 million capacity budget. Seagate’s fiscal 2026 free cash flow was $3.1 billion on $12.195 billion of revenue, with a 33.6 percent GAAP operating margin. Western Digital’s fiscal 2026 operating income was $4.453 billion GAAP on $12.919 billion of revenue, and fourth-quarter GAAP operating margin was 41.7 percent, against 43.0 percent at Seagate. Those margins are the scarcity premium. TrendForce, citing Bloomberg, said a deal would likely draw antitrust scrutiny and could hand the winner pricing power over heads rivals still buy in a spike. No complaint and no confirmation was in Tuesday’s filings. Until someone owns the head unit, or says they will not, the capacity plan and the reported bid are two stories about one bottleneck.

The standing guides assume the old supply setup, and Tuesday did not revise them. Seagate’s 29 July guide is fiscal first-quarter revenue of $4.1 billion, plus or minus $100 million, and non-GAAP earnings of $7.30, plus or minus $0.20, against a $5.71 non-GAAP quarter just printed. Western Digital’s 5 August guide is the same revenue range and non-GAAP earnings of $4.00, plus or minus $0.15, against $3.56 just printed. The revenue midpoint matches. The earnings step-up does not.

What happens next

Wednesday 7 October is a dividend date, not a new fundamental. Seagate’s board, in the 29 July release, declared $0.74 a share, payable on 7 October 2026 to holders of record on 24 September. On the 227 million shares outstanding at 3 July, that is about $168 million. It does not say whether TDK is for sale. Wednesday’s US cash session had not opened when these closes were taken. Any reaction to Heise’s report, that a Toshiba spokesperson said no meeting had taken place, belongs to Wednesday’s session. It is not a revision of Tuesday’s $805.63 or $411.04.

The next company dates on public calendars are estimates. StockAnalysis, on the pages fetched 7 October, lists 27 October 2026 for Seagate and 29 October 2026 for Western Digital. The July and August releases set the numbers, not those calendar entries. If management reaffirms the $4.1 billion revenue midpoints and does not address head supply, the market is still holding an unconfirmed Bloomberg report against a guide that assumed the prior sourcing. If either company cuts the guide, the cut is the new fact. If either company says, in its own words, that it is or is not bidding for TDK, the people-familiar story ends. This desk did not find that sentence in a Tuesday filing.

Further out, the clock is Toshiba’s fiscal 2027, the horizon Nikkei gave for doubling capacity, not a share-price target. The $380 million budget becomes competing exabytes only if media and heads expand with it. That was Merchant’s 2 October point, and it is what the 6 October heads report is about. A change of control at TDK, if announced, is a larger event and, on Bloomberg’s account, would face antitrust review before it changed a shipment. The test until then is whether the two stocks move together. They did on Friday. They did not on Tuesday.

Frequently asked questions

Why did Seagate and Western Digital fall on Tuesday?

The fresh public item was a Bloomberg report on 6 October 2026 that Seagate and Toshiba are competing for TDK’s magnetic-heads business, in a deal sources put at as much as several billion dollars. That is separate from Friday’s Nikkei report of a $380 million Toshiba capacity plan. Neither company filed an 8-K on Tuesday. The official closes were $805.63, down 9.18 percent, and $411.04, down 6.93 percent.

Was the TDK deal confirmed?

No fetched document shows a signed deal, a price, or a company announcement. Bloomberg attributed the contest to people familiar with private talks. Invezz reported on 6 October that a Toshiba spokesperson called the account inconsistent with the company’s understanding. Heise reported on Wednesday 7 October that a spokesperson said no meeting took place, and that Seagate and TDK declined to comment. Until a filing confirms it, the bid is a report.

Did the chief executive’s share sale cause Tuesday’s drop?

No. William D. Mosley sold 30,000 Seagate shares on 1 October for $27,670,452.16, in two Forms 4 filed on 2 October. A “$17.4 million” line is only the first form. Both say the sales followed a Rule 10b5-1 plan adopted on 18 February 2026. The sale was before Friday’s drop and five days before Tuesday. A February plan is not a reaction to an October headline.

How is Tuesday different from the 2 October selloff?

Friday’s Nasdaq closes were $848.99 and $415.29, each about 10.2 percent below Thursday, after the capacity report. Monday bounced to $887.09 and $441.64. Tuesday broke that symmetry: Seagate finished 5.11 percent under Friday’s close, Western Digital only 1.02 percent under it. The new report was about who might own TDK’s heads. Volume was a bit over half of Friday’s.

When do the companies report, and what are the guides?

The guides are company statements. Seagate, on 29 July, set fiscal first-quarter 2027 revenue at $4.1 billion plus or minus $100 million and non-GAAP earnings at $7.30 plus or minus $0.20. Western Digital, on 5 August, set the same revenue range and non-GAAP earnings at $4.00 plus or minus $0.15. StockAnalysis lists estimated dates of 27 and 29 October 2026. Those dates were not in the releases.

Is Sandisk part of this trade?

No. Western Digital’s 5 August 2026 release says that on 21 February 2025 it separated its flash business into Sandisk Corporation. Sandisk is a different listed company. The Tuesday closes in this piece are Seagate at $805.63 and Western Digital at $411.04. A flash-memory print is a different tape and is not a cause used here.

This is not financial advice.