Seagate holder Mosley plans $74.6M stock sale

Rhea-AI Filing Summary

Seagate Technology Holdings plc (STX) received a Rule 144 notice from William D. Mosley covering the proposed sale of up to 90,000 shares of common stock, with an aggregate market value of $74,554,200.00, when shares outstanding were 226,644,518 as of 09/01/2026.

The planned sales include 42,000 shares to be received upon the exercise of stock options over the next three months and 48,000 shares acquired from vesting of restricted and performance stock units during 09/24/2020–09/14/2025. The approximate sale date is listed as 09/01/2026 on NASDAQ. In the prior three months, Mosley reported several sales of Seagate common stock, including 30,000 shares on 08/03/2026 and 30,000 shares on 07/01/2026, noted as 10b5-1 sales.

Key Figures

Shares to be sold under Rule 144: 90,000 shares Aggregate market value of securities to be sold: $74,554,200.00 Shares outstanding: 226,644,518 shares +5 more

8 metrics

Shares to be sold under Rule 144 90,000 shares Proposed sale of Seagate common stock reported by William D. Mosley

Aggregate market value of securities to be sold $74,554,200.00 Based on Seagate common stock covered by the Rule 144 notice

Shares outstanding 226,644,518 shares Seagate common shares outstanding as of 09/01/2026

Shares from exercise of stock options 42,000 shares Securities to be received and sold over the next three months

Shares from restricted and performance stock units 48,000 shares Shares acquired upon vesting during 09/24/2020–09/14/2025

Sale on 07/01/2026 30,000 shares for $27,444,659.00 Reported Seagate common stock sale marked as 10b5-1

Sale on 08/03/2026 30,000 shares for $24,511,132.00 Reported Seagate common stock sale marked as 10b5-1

Sale on 08/21/2026 18,139 shares for $15,406,446.72 Reported Seagate common stock sale in past three months

Key Terms

Rule 144, 10b5-1, restricted and performance stock units, Exercise of Stock Options

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.

10b5-1 regulatory

"10b5-1 Sales for MOSLEY 121 Woodlands Avenue 5 Singapore"

A 10b5-1 plan is a pre-set schedule that lets company insiders buy or sell shares according to written instructions made when they do not possess material, nonpublic information. Think of it as a timed automatic payment for stock trades: it helps insiders avoid accusations of trading on secret information and gives outside investors a clearer signal about whether sales are routine or potentially informative about the company’s prospects.

restricted and performance stock units financial

"The 48,000 securities to be sold were acquired upon the vesting of restricted and performance stock units"

Exercise of Stock Options financial

"Common | 09/01/2026 | Exercise of Stock Options | Issuer"

FAQ

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

It discloses that William D. Mosley filed a Rule 144 notice to sell up to 90,000 shares of Seagate common stock, with an aggregate market value of $74,554,200.00, when 226,644,518 shares were outstanding as of 09/01/2026.

How many Seagate (STX) shares is Mosley planning to sell and how are they sourced?

Mosley plans to sell 90,000 shares of Seagate common stock. This includes 42,000 shares to be received upon the exercise of stock options and 48,000 shares acquired from vesting of restricted and performance stock units between 09/24/2020 and 09/14/2025.

When are the proposed Seagate (STX) stock sales expected to occur?

The notice lists an approximate sale date of 09/01/2026, with the 42,000 option-related shares to be received upon exercises over the next three months. Sales are indicated for trading on NASDAQ.

What Seagate (STX) stock sales has Mosley reported in the past three months?

Reported sales include 30,000 shares on 07/01/2026 for $27,444,659.00, 30,000 shares on 08/03/2026 for $24,511,132.00, and 18,139 shares on 08/21/2026 for $15,406,446.72, with the two larger trades noted as 10b5-1 sales.

What are the details of Seagate (STX) shares outstanding mentioned in the filing?

The filing states that 226,644,518 Seagate common shares were outstanding as of 09/01/2026; this figure serves as a baseline and is separate from the 90,000 shares covered by the Rule 144 sale notice.

What types of equity awards underlie Mosley’s planned Seagate (STX) sales?

The planned sales are tied to equity awards consisting of stock options for 42,000 shares and restricted and performance stock units that produced 48,000 shares vested during the period 09/24/2020 through 09/14/2025.

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

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Available on EDGAR 09/01/2026 - 04:42 PM Accepted by SEC EDGAR 09/01/2026 - 04:41 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	6560182562
Name of Person for Whose Account the Securities are To Be Sold	WILLIAM D. MOSLEY
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	Director
Relationship to Issuer	Officer

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	Morgan Stanley Smith Barney LLC Executive Financial Services 1 New York Plaza 8th Floor New York NY 10004	90000	74554200.00	226644518	09/01/2026	NASDAQ

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	09/01/2026	Exercise of Stock Options	Issuer			42000	09/01/2026	Cash
Common	09/24/2020	Restricted and Performance Stock Units	Issuer			48000	09/24/2020	N/A

* 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 121 Woodlands Avenue 5 Singapore U0 739009	Common	08/21/2026	18139	15406446.72
10b5-1 Sales for WILLIAM MOSLEY 121 Woodlands Avenue 5 Singapore U0 739009	Common	08/03/2026	30000	24511132.00
10b5-1 Sales for WILLIAM MOSLEY 121 Woodlands Avenue 5 Singapore U0 739009	Common	07/01/2026	30000	27444659.00
WILLIAM D. MOSLEY 121 Woodlands Avenue 5 Singapore U0 739009	Common	06/12/2026	1769	1557053.99

144: Remarks and Signature

Remarks	The 42,000 securities to be sold were and will be received upon the exercise of stock options over the next three months. The dates of acquisition and payment were and will be the dates of exercise/sale. The 48,000 securities to be sold were acquired upon the vesting of restricted and performance stock units during the period of 09/24/2020 through 09/14/2025.
Date of Notice	09/01/2026
Date of Plan Adoption or Giving of Instruction, If Relying on Rule 10b5-1	02/18/2026
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/ William D. Mosley
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)