Seagate: Mosley plans $2.58M tax-withholding sale

William D. Mosley filed a Rule 144 notice to sell Seagate shares obtained from RSU vesting, primarily to cover tax withholding obligations.

Rhea-AI Filing Summary

Seagate Technology Holdings plc (STX) is the issuer for which William D. Mosley has filed a notice under Rule 144 to sell common stock. The notice covers a proposed sale of 2,992 shares of common stock through Morgan Stanley, with an aggregate market value of $2,579,258.10, based on 226,644,518 shares outstanding as of September 10, 2026.

The securities to be sold arise from restricted stock unit vesting on September 9, 2026, described as compensation for services. The filer states that sales are to be made pursuant to an issuer-mandated sell-to-cover arrangement used solely to satisfy tax withholding obligations. The filing also lists several prior sales of Seagate common stock by Mosley during the past three months.

Key Figures

Shares proposed to be sold: 2,992 shares Aggregate market value of shares to be sold: $2,579,258.10 Shares outstanding: 226,644,518 shares +6 more

9 metrics

Shares proposed to be sold 2,992 shares Common stock covered by the Rule 144 notice

Aggregate market value of shares to be sold $2,579,258.10 Value of 2,992 Seagate common shares under the notice

Shares outstanding 226,644,518 shares Seagate common stock outstanding as of September 10, 2026

Sale on June 10, 2026 2,855 shares; $2,345,874.00 Common stock sold by William D. Mosley

Sale on June 12, 2026 1,768 shares; $1,556,394.00 Common stock sold by William D. Mosley

Sale on July 1, 2026 30,000 shares; $27,444,658.12 Common stock sold by William D. Mosley

Sale on August 3, 2026 30,000 shares; $24,511,131.27 Common stock sold by William D. Mosley

Sale on August 21, 2026 14,746 shares; $12,524,373.54 Common stock sold by William D. Mosley

Sale on September 1, 2026 30,000 shares; $24,488,282.26 Common stock sold by William D. Mosley

Key Terms

Rule 144, Restricted Stock Unit Vesting, sell-to-cover, Attorney-in-Fact

4 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 Vesting financial

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

sell-to-cover financial

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

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.

FAQ

What does the Form 144 filing for Seagate Technology Holdings plc (STX) disclose?

It discloses that William D. Mosley has filed a notice under Rule 144 to sell 2,992 shares of Seagate common stock through Morgan Stanley, with sales stated to be pursuant to an issuer-mandated sell-to-cover arrangement for tax withholding on vested RSUs.

How many Seagate (STX) shares are covered by this Rule 144 notice?

The notice covers a proposed sale of 2,992 shares of Seagate common stock, with an aggregate market value of $2,579,258.10, based on 226,644,518 shares outstanding as of September 10, 2026.

What is the source of the Seagate (STX) shares being sold by William D. Mosley?

The shares come from restricted stock unit vesting on September 9, 2026, identified as compensation for services. The remarks state that sales will be made pursuant to an issuer-mandated sell-to-cover used solely to satisfy tax withholding obligations.

What prior Seagate (STX) stock sales by William D. Mosley are reported in the last three months?

Reported prior sales include 2,855 shares on June 10, 2026; 1,768 shares on June 12, 2026; 30,000 shares on July 1, 2026; 30,000 shares on August 3, 2026; 14,746 shares on August 21, 2026; and 30,000 shares on September 1, 2026.

Who is executing the planned Seagate (STX) share sale and where are the shares listed?

The proposed sale of 2,992 Seagate common shares is to be executed through Morgan Stanley at 1 New York Plaza. The common stock is listed on the NASDAQGS, as stated in the securities information section.

Who signed the Form 144 related to Seagate (STX) on behalf of William D. Mosley?

The notice is signed by /s/ Dawn Ledbetter, identified as Attorney-in-Fact for William D. Mosley, dated September 10, 2026.

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

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Available on EDGAR 09/10/2026 - 07:37 PM Accepted by SEC EDGAR 09/10/2026 - 07:36 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	2992	2579258.10	226644518	09/10/2026	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	09/09/2026	Restricted Stock Unit Vesting	Issuer			2415	09/09/2026	Compensation for services
Common Stock	09/09/2026	Restricted Stock Unit Vesting	Issuer			2815	09/09/2026	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 47488 Kato Rd Fremont CA 94538	Common Stock	06/10/2026	2855	2345874.00
William D. Mosley 47488 Kato Road Fremont CA 94538	Common Stock	06/12/2026	1768	1556394.00
William D. Mosley 474888 Kato Road Fremont CA 94538	Common Stock	07/01/2026	30000	27444658.12
William D. Mosley 47488 Kato Road 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

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	09/10/2026
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)