William D. Mosley - 03 Aug 2026 Form 4 Insider Report for Seagate Technology Holdings plc (STX)

Reporting relationship: CEO, Director
Issuer ticker: STX
Reported as of: 03 Aug 2026
Net transaction value: -$14,130,293
SEC form: 4
Accepted by SEC: 04 Aug 2026, 18:09:40 UTC
Prior SEC filing: 31 Jul 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 04 Aug 2026.

Key facts

This page summarizes William D. Mosley's Form 4 filing for Seagate Technology Holdings plc (STX).
19 reported transactions and 0 derivative rows are listed below.
Accepted by SEC: 04 Aug 2026, 18:09.

Change

Previous filing in this sequence was filed on 31 Jul 2026.
Current net transaction value: -$14,130,293.

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: 04 Aug 2026

Reported non-derivative transactions

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

STX transaction

Ordinary Shares

Sale

Transaction value: $327,765
Shares: -400
Change %: -0.13%
Price: $819.41
Shares after: 312,197
Date: 03 Aug 2026
Ownership: Direct
Footnotes: F1, F2

STX transaction

Ordinary Shares

Sale

Transaction value: $426,580
Shares: -520
Change %: -0.17%
Price: $820.35
Shares after: 311,677
Date: 03 Aug 2026
Ownership: Direct
Footnotes: F3

STX transaction

Ordinary Shares

Sale

Transaction value: $472,339
Shares: -575
Change %: -0.18%
Price: $821.46
Shares after: 311,102
Date: 03 Aug 2026
Ownership: Direct
Footnotes: F4

STX transaction

Ordinary Shares

Sale

Transaction value: $690,947
Shares: -840
Change %: -0.27%
Price: $822.56
Shares after: 310,262
Date: 03 Aug 2026
Ownership: Direct
Footnotes: F5

STX transaction

Ordinary Shares

Sale

Transaction value: $922,272
Shares: -1,120
Change %: -0.36%
Price: $823.46
Shares after: 309,142
Date: 03 Aug 2026
Ownership: Direct
Footnotes: F6

STX transaction

Ordinary Shares

Sale

Transaction value: $1,319,314
Shares: -1,600
Change %: -0.52%
Price: $824.57
Shares after: 307,542
Date: 03 Aug 2026
Ownership: Direct
Footnotes: F7

STX transaction

Ordinary Shares

Sale

Transaction value: $1,056,814
Shares: -1,280
Change %: -0.42%
Price: $825.64
Shares after: 306,262
Date: 03 Aug 2026
Ownership: Direct
Footnotes: F8

STX transaction

Ordinary Shares

Sale

Transaction value: $1,641,120
Shares: -1,985
Change %: -0.65%
Price: $826.76
Shares after: 304,277
Date: 03 Aug 2026
Ownership: Direct
Footnotes: F9

STX transaction

Ordinary Shares

Sale

Transaction value: $1,488,979
Shares: -1,799
Change %: -0.59%
Price: $827.67
Shares after: 302,478
Date: 03 Aug 2026
Ownership: Direct
Footnotes: F10

STX transaction

Ordinary Shares

Sale

Transaction value: $1,359,725
Shares: -1,641
Change %: -0.54%
Price: $828.60
Shares after: 300,837
Date: 03 Aug 2026
Ownership: Direct
Footnotes: F11

STX transaction

Ordinary Shares

Sale

Transaction value: $1,343,421
Shares: -1,619
Change %: -0.54%
Price: $829.78
Shares after: 299,218
Date: 03 Aug 2026
Ownership: Direct
Footnotes: F12

STX transaction

Ordinary Shares

Sale

Transaction value: $1,628,436
Shares: -1,960
Change %: -0.66%
Price: $830.83
Shares after: 297,258
Date: 03 Aug 2026
Ownership: Direct
Footnotes: F13

STX transaction

Ordinary Shares

Sale

Transaction value: $266,248
Shares: -320
Change %: -0.11%
Price: $832.02
Shares after: 296,938
Date: 03 Aug 2026
Ownership: Direct
Footnotes: F14

STX transaction

Ordinary Shares

Sale

Transaction value: $333,090
Shares: -400
Change %: -0.13%
Price: $832.73
Shares after: 296,538
Date: 03 Aug 2026
Ownership: Direct
Footnotes: F15

STX transaction

Ordinary Shares

Sale

Transaction value: $166,782
Shares: -200
Change %: -0.07%
Price: $833.91
Shares after: 296,338
Date: 03 Aug 2026
Ownership: Direct
Footnotes: F16

STX transaction

Ordinary Shares

Sale

Transaction value: $151,146
Shares: -181
Change %: -0.06%
Price: $835.06
Shares after: 296,157
Date: 03 Aug 2026
Ownership: Direct
Footnotes: F17

STX transaction

Ordinary Shares

Sale

Transaction value: $334,396
Shares: -400
Change %: -0.14%
Price: $835.99
Shares after: 295,757
Date: 03 Aug 2026
Ownership: Direct
Footnotes: F18

STX transaction

Ordinary Shares

Sale

Transaction value: $133,883
Shares: -160
Change %: -0.05%
Price: $836.77
Shares after: 295,597
Date: 03 Aug 2026
Ownership: Direct
Footnotes: F19

STX transaction

Ordinary Shares

Sale

Transaction value: $67,038
Shares: -80
Change %: -0.03%
Price: $837.98
Shares after: 295,517
Date: 03 Aug 2026
Ownership: Direct
Footnotes: F20

^* 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 20 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 $818.84 to $819.71. 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 $819.89 to $820.88. 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 $820.99 to $821.98. 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 $822.01 to $822.97. 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 $823.085 to $824.07. 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 $824.15 to $825.11. 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 $825.16 to $826.15. 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 $826.19 to $827.18. 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 $827.20 to $828.19. 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 $828.22 to $829.16. 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 $829.33 to $830.31. 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 $830.33 to $831.27. 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 $831.43 to $832.31. 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 $832.43 to $833.40. 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 $833.43 to $834.36. 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 F17

These Ordinary Shares were sold in multiple trades at prices ranging from $834.46 to $835.37. 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 F18

These Ordinary Shares were sold in multiple trades at prices ranging from $835.55 to $836.52. 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 F19

These Ordinary Shares were sold in multiple trades at prices ranging from $836.58 to $837.21. 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 F20

These Ordinary Shares were sold in multiple trades at prices ranging from $837.97 to $837.99. 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.