William D. Mosley - 01 Oct 2026 Form 4 Insider Report for Seagate Technology Holdings plc (STX)

Reporting relationship: CEO, Director
Issuer ticker: STX
Reported as of: 01 Oct 2026
Net transaction value: -$10,293,464
SEC form: 4
Accepted by SEC: 02 Oct 2026, 16:07:58 UTC
Prior SEC filing: 16 Sep 2026
Source filing: View source filing
Reporting owner signature: /s/ Louis J. Thorson, Attorney-in-Fact for William D. Mosley

Key filing fact

William D. Mosley filed Form 4 for Seagate Technology Holdings plc (STX) on 02 Oct 2026.

Key facts

This page summarizes William D. Mosley's Form 4 filing for Seagate Technology Holdings plc (STX).
16 reported transactions and 0 derivative rows are listed below.
Accepted by SEC: 02 Oct 2026, 16:07.

Change

Previous filing in this sequence was filed on 16 Sep 2026.
Current net transaction value: -$10,293,464.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0001388390 Primary reporting owner

MOSLEY WILLIAM D

Relationship: CEO, Director
Address: SEAGATE TECHNOLOGY HOLDINGS PLC, 47488 KATO ROAD, FREMONT
Signature: /s/ Louis J. Thorson, Attorney-in-Fact for William D. Mosley
Signature date: 02 Oct 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

STX transaction

Ordinary Shares

Sale

Transaction value: $334,443
Shares: -360
Change %: -0.1%
Price: $929.01
Shares after: 372,750
Date: 01 Oct 2026
Ownership: Direct
Footnotes: F1, F2

STX transaction

Ordinary Shares

Sale

Transaction value: $795,179
Shares: -855
Change %: -0.23%
Price: $930.03
Shares after: 371,895
Date: 01 Oct 2026
Ownership: Direct
Footnotes: F3

STX transaction

Ordinary Shares

Sale

Transaction value: $1,550,105
Shares: -1,665
Change %: -0.45%
Price: $930.99
Shares after: 370,230
Date: 01 Oct 2026
Ownership: Direct
Footnotes: F4

STX transaction

Ordinary Shares

Sale

Transaction value: $1,230,289
Shares: -1,320
Change %: -0.36%
Price: $932.04
Shares after: 368,910
Date: 01 Oct 2026
Ownership: Direct
Footnotes: F5

STX transaction

Ordinary Shares

Sale

Transaction value: $783,952
Shares: -840
Change %: -0.23%
Price: $933.28
Shares after: 368,070
Date: 01 Oct 2026
Ownership: Direct
Footnotes: F6

STX transaction

Ordinary Shares

Sale

Transaction value: $768,037
Shares: -822
Change %: -0.22%
Price: $934.35
Shares after: 367,248
Date: 01 Oct 2026
Ownership: Direct
Footnotes: F7

STX transaction

Ordinary Shares

Sale

Transaction value: $598,496
Shares: -640
Change %: -0.17%
Price: $935.15
Shares after: 366,608
Date: 01 Oct 2026
Ownership: Direct
Footnotes: F8

STX transaction

Ordinary Shares

Sale

Transaction value: $710,750
Shares: -759
Change %: -0.21%
Price: $936.43
Shares after: 365,849
Date: 01 Oct 2026
Ownership: Direct
Footnotes: F9

STX transaction

Ordinary Shares

Sale

Transaction value: $542,713
Shares: -579
Change %: -0.16%
Price: $937.33
Shares after: 365,270
Date: 01 Oct 2026
Ownership: Direct
Footnotes: F10

STX transaction

Ordinary Shares

Sale

Transaction value: $600,524
Shares: -640
Change %: -0.18%
Price: $938.32
Shares after: 364,630
Date: 01 Oct 2026
Ownership: Direct
Footnotes: F11

STX transaction

Ordinary Shares

Sale

Transaction value: $676,275
Shares: -720
Change %: -0.2%
Price: $939.27
Shares after: 363,910
Date: 01 Oct 2026
Ownership: Direct
Footnotes: F12

STX transaction

Ordinary Shares

Sale

Transaction value: $75,216
Shares: -80
Change %: -0.02%
Price: $940.20
Shares after: 363,830
Date: 01 Oct 2026
Ownership: Direct
Footnotes: F13

STX transaction

Ordinary Shares

Sale

Transaction value: $37,649
Shares: -40
Change %: -0.01%
Price: $941.22
Shares after: 363,790
Date: 01 Oct 2026
Ownership: Direct

STX transaction

Ordinary Shares

Sale

Transaction value: $264,100
Shares: -280
Change %: -0.08%
Price: $943.21
Shares after: 363,510
Date: 01 Oct 2026
Ownership: Direct
Footnotes: F14

STX transaction

Ordinary Shares

Sale

Transaction value: $415,715
Shares: -440
Change %: -0.12%
Price: $944.81
Shares after: 363,070
Date: 01 Oct 2026
Ownership: Direct
Footnotes: F15

STX transaction

Ordinary Shares

Sale

Transaction value: $910,023
Shares: -962
Change %: -0.26%
Price: $945.97
Shares after: 362,108
Date: 01 Oct 2026
Ownership: Direct
Footnotes: F16

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Rule 10b5-1 trading plan

These transactions were reported as open-market trades under a Rule 10b5-1 plan. The plan lets an insider set trading instructions in advance, which can reduce the risk of trading while in possession of material nonpublic information.

Original filing language: transaction made pursuant to a contract, instruction, or written plan intended to satisfy Rule 10b5-1(c).

Explanation of responses 16 footnotes

Footnote F1

All transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on February 18, 2026.

Footnote F2

These Ordinary Shares were sold in multiple trades at prices ranging from $928.44 to $929.30. The price reported above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide upon request to the SEC staff, the Issuer, or a security holder of the Issuer, full information regarding the number of shares and prices at which the transaction was effected.

Footnote F3

These Ordinary Shares were sold in multiple trades at prices ranging from $929.51 to $930.50. The price reported above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide upon request to the SEC staff, the Issuer, or a security holder of the Issuer, full information regarding the number of shares and prices at which the transaction was effected.

Footnote F4

These Ordinary Shares were sold in multiple trades at prices ranging from $930.53 to $931.48. The price reported above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide upon request to the SEC staff, the Issuer, or a security holder of the Issuer, full information regarding the number of shares and prices at which the transaction was effected.

Footnote F5

These Ordinary Shares were sold in multiple trades at prices ranging from $931.56 to $932.55. The price reported above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide upon request to the SEC staff, the Issuer, or a security holder of the Issuer, full information regarding the number of shares and prices at which the transaction was effected.

Footnote F6

These Ordinary Shares were sold in multiple trades at prices ranging from $932.73 to $933.67. The price reported above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide upon request to the SEC staff, the Issuer, or a security holder of the Issuer, full information regarding the number of shares and prices at which the transaction was effected.

Footnote F7

These Ordinary Shares were sold in multiple trades at prices ranging from $933.77 to $934.76. The price reported above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide upon request to the SEC staff, the Issuer, or a security holder of the Issuer, full information regarding the number of shares and prices at which the transaction was effected.

Footnote F8

These Ordinary Shares were sold in multiple trades at prices ranging from $934.83 to $935.70. The price reported above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide upon request to the SEC staff, the Issuer, or a security holder of the Issuer, full information regarding the number of shares and prices at which the transaction was effected.

Footnote F9

These Ordinary Shares were sold in multiple trades at prices ranging from $935.84 to $936.80. The price reported above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide upon request to the SEC staff, the Issuer, or a security holder of the Issuer, full information regarding the number of shares and prices at which the transaction was effected.

Footnote F10

These Ordinary Shares were sold in multiple trades at prices ranging from $936.88 to $937.83. The price reported above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide upon request to the SEC staff, the Issuer, or a security holder of the Issuer, full information regarding the number of shares and prices at which the transaction was effected.

Footnote F11

These Ordinary Shares were sold in multiple trades at prices ranging from $937.91 to $938.67. The price reported above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide upon request to the SEC staff, the Issuer, or a security holder of the Issuer, full information regarding the number of shares and prices at which the transaction was effected.

Footnote F12

These Ordinary Shares were sold in multiple trades at prices ranging from $938.92 to $939.89. The price reported above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide upon request to the SEC staff, the Issuer, or a security holder of the Issuer, full information regarding the number of shares and prices at which the transaction was effected.

Footnote F13

These Ordinary Shares were sold in multiple trades at prices ranging from $940.19 to $940.21. The price reported above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide upon request to the SEC staff, the Issuer, or a security holder of the Issuer, full information regarding the number of shares and prices at which the transaction was effected.

Footnote F14

These Ordinary Shares were sold in multiple trades at prices ranging from $942.72 to $943.68. The price reported above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide upon request to the SEC staff, the Issuer, or a security holder of the Issuer, full information regarding the number of shares and prices at which the transaction was effected.

Footnote F15

These Ordinary Shares were sold in multiple trades at prices ranging from $944.50 to $945.46. The price reported above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide upon request to the SEC staff, the Issuer, or a security holder of the Issuer, full information regarding the number of shares and prices at which the transaction was effected.

Footnote F16

These Ordinary Shares were sold in multiple trades at prices ranging from $945.60 to $946.34. The price reported above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide upon request to the SEC staff, the Issuer, or a security holder of the Issuer, full information regarding the number of shares and prices at which the transaction was effected.