Seagate’s Mosley plans $1.53M tax-cover sale

Insider William D. Mosley filed a Rule 144 notice to sell Seagate shares mainly to cover tax withholding from recent RSU vesting.

Rhea-AI Filing Summary

Seagate Technology Holdings plc (STX) has a notice from insider William D. Mosley under Rule 144 to sell Seagate common stock through Morgan Stanley. The notice lists 1,963 shares of common stock with an aggregate market value of $1,533,731.00, against 226,644,518 shares outstanding, with an approximate sale date of September 14, 2026 on NASDAQGS.

The shares relate to 3,319 restricted stock units vesting on September 11, 2026, described as compensation for services. The remarks state that sales will be made pursuant to an issuer-mandated sell-to-cover solely to satisfy tax withholding obligations. Over the prior three months Mosley sold 30,000 shares on July 1, 2026, 30,000 on August 3, 2026, 14,746 on August 21, 2026, 30,000 on September 1, 2026, and 2,849 on September 10, 2026, for the aggregate amounts shown.

Key Figures

Shares to be sold: 1,963 shares of common stock Aggregate market value of planned sale: $1,533,731.00 Shares outstanding: 226,644,518 shares +5 more

8 metrics

Shares to be sold 1,963 shares of common stock Planned sale under Rule 144 through Morgan Stanley

Aggregate market value of planned sale $1,533,731.00 Value of the 1,963 shares covered by the notice

Shares outstanding 226,644,518 shares Seagate common stock outstanding at time of notice

Restricted stock units vesting 3,319 units RSU vesting on September 11, 2026 as compensation for services

Sale on July 1, 2026 30,000 shares; $27,444,658.12 aggregate Common stock sold in the past three months

Sale on August 3, 2026 30,000 shares; $24,511,131.27 aggregate Common stock sold in the past three months

Sale on August 21, 2026 14,746 shares; $12,524,373.54 aggregate Common stock sold in the past three months

Sale on September 1, 2026 30,000 shares; $24,488,282.26 aggregate Common stock sold in the past three months

Key Terms

Rule 144, Restricted Stock Unit, sell-to-cover, Attorney-in-Fact, +1 more

5 terms

Rule 144 regulatory

"See the definition of "person" in paragraph (a) of Rule 144."

Rule 144 is a U.S. securities regulation that sets conditions under which restricted or insider-held shares can be legally resold to the public, such as required holding periods, availability of public information, limits on how much can be sold at once, and certain filing requirements. For investors it matters because it determines when previously locked-up shares can enter the market — like a release valve that can increase supply, affect share price, and signal insider intent.

Restricted Stock Unit financial

"Common stock | 09/11/2026 | Restricted Stock Unit Vesting | Issuer"

A restricted stock unit is a promise from a company to give an employee shares of stock after certain conditions are met, like staying with the company for a set amount of time. It’s like earning a bonus that turns into company stock once you’ve proven your commitment, making it a way to motivate and reward employees.

sell-to-cover financial

"Sales to be made pursuant to Issuer mandated sell-to-cover solely to satisfy"

Sell-to-cover is when part of newly issued or exercised company stock is immediately sold to pay required taxes and fees, so the recipient keeps the remaining shares. For investors this matters because it reduces the number of shares insiders or employees actually hold after a grant, can create small, routine share sales that aren’t signal of cashing out, and slightly increases share supply on the market—like selling a portion of a paycheck to cover the tax bill.

Attorney-in-Fact regulatory

"Signature | /s/ Dawn Ledbetter. Attorney-in-Fact for William D. Mosley"

An attorney-in-fact is the person or entity given legal authority through a power of attorney to act on behalf of another for specific tasks, such as signing documents, voting shares, or handling transactions. For investors, this matters because it lets a trusted representative make timely decisions or complete paperwork when the owner cannot, much like handing keys to someone to run errands on your behalf—so checks on scope and limits of that authority are important.

compensation for services financial

"3319 | 09/11/2026 | Compensation for services"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What does Seagate (STX) insider William D. Mosley plan to sell under this Rule 144?

The notice lists 1,963 shares of Seagate common stock with an aggregate market value of $1,533,731.00, to be sold through Morgan Stanley, with an approximate sale date of September 14, 2026 on NASDAQGS.

What Seagate (STX) equity award is associated with the planned Rule 144 sale?

The filing links the sale to 3,319 restricted stock units that vest on September 11, 2026, described as compensation for services. The insider indicates sales will be made to satisfy related tax withholding obligations.

How does the planned Seagate (STX) sale compare with shares outstanding?

The notice states that the 1,963 shares covered have an aggregate market value of $1,533,731.00, compared with 226,644,518 shares of Seagate common stock outstanding as of around the planned sale date of September 14, 2026.

What Seagate (STX) shares did William D. Mosley sell in the past three months?

Over the prior three months, Mosley sold 30,000 shares on July 1, 2026, 30,000 on August 3, 2026, 14,746 on August 21, 2026, 30,000 on September 1, 2026, and 2,849 on September 10, 2026, for the aggregate amounts listed in the filing.

What is the stated purpose of William D. Mosley’s planned Seagate (STX) share sales?

The remarks explain that sales are to be made under an issuer mandated sell-to-cover arrangement, used solely to satisfy tax withholding obligations related to the restricted stock unit vesting.

Who signed the Rule 144 notice related to Seagate (STX)?

The notice is signed “/s/ Dawn Ledbetter, Attorney-in-Fact for William D. Mosley”, indicating it was executed on Mosley’s behalf under a power of attorney. The date of the notice is September 14, 2026.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 09/14/2026 - 07:57 PM Accepted by SEC EDGAR 09/14/2026 - 07:57 PM Learn about SEC filing dates

Form 144 Filer Information	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 144 NOTICE OF PROPOSED SALE OF SECURITIES PURSUANT TO RULE 144 UNDER THE SECURITIES ACT OF 1933
FORM 144

144: Filer Information

Filer CIK	0001388390
Filer CCC	XXXXXXXX
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144: Issuer Information

Name of Issuer	Seagate Technology Holdings plc
SEC File Number	001-31560
Address of Issuer	121 WOODLANDS AVENUE 5 SINGAPORE SINGAPORE 739009
Phone	65 6412 5172
Name of Person for Whose Account the Securities are To Be Sold	MOSLEY WILLIAM D
See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.
Relationship to Issuer	Officer
Relationship to Issuer	Director

144: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Common Stock	Morgan Stanley 1 New York Plaza 8th Floor New York NY 10004	1963	1533731.00	226644518	09/14/2026	NASDAQGS

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Is this a Gift?	Date Donor Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Common stock	09/11/2026	Restricted Stock Unit Vesting	Issuer			3319	09/11/2026	Compensation for services

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

Name and Address of Seller	Title of Securities Sold	Date of Sale	Amount of Securities Sold	Gross Proceeds
William D. Mosley 474888 Kato Rd Fremont CA 94538	Common Stock	07/01/2026	30000	27444658.12
William D. Mosley 47488 Kato Rd Fremont CA 94538	Common Stock	08/03/2026	30000	24511131.27
William D. Mosley 47488 Kato Rd Fremont CA 94538	Common Stock	08/21/2026	14746	12524373.54
William D. Mosley 47488 Kato Rd. Fremont CA 94538	Common Stock	09/01/2026	30000	24488282.26
William D. Mosley 47488 Kato Rd Fremont CA 94538	Common Stock	09/10/2026	2849	2456436.29

144: Remarks and Signature

Remarks	Sales to be made pursuant to Issuer mandated sell-to-cover solely to satisfy tax withholding obligations.
Date of Notice	09/14/2026
ATTENTION:
The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.
Signature	/s/ Dawn Ledbetter. Attorney-in-Fact for William D. Mosley
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)