As of October 03, 2026, the three largest insider holders of STX are Holdings, L.P. Valueact (Director, 13.44Mn shares), William D Mosley (Ceo, 378.11K shares), Stephen J Luczo (Executive Chairman Cob, 225.94K shares).
| # | Insider | Position | Direct | Indirect | Total | Share of Insiders | Last Filed |
|---|---|---|---|---|---|---|---|
| 1 | Holdings, L.P. Valueact | Director, Other | 0 | 13,437,070 | 13,437,070 | 93.4% | 22 Feb, 2022 |
| 2 | William D Mosley | Ceo | 373,110 | 0 | 373,110 | 2.6% | 02 Oct, 2026 |
| 3 | Stephen J Luczo | Executive Chairman Cob | 0 | 225,941 | 225,941 | 1.6% | 08 Mar, 2022 |
| 4 | Gianluca Romano | Evp Cfo | 70,757 | 0 | 70,757 | 0.5% | 16 Sep, 2026 |
| 5 | Ravi Naik | Evp, Lyve Storage Services | 38,857 | 0 | 38,857 | 0.3% | 23 Mar, 2023 |
| 6 | Jeffrey D. Nygaard | Evp, Operations And Technology | 30,360 | 0 | 30,360 | 0.2% | 02 Feb, 2023 |
| 7 | Richard L Clemmer | Director | 29,704 | 0 | 29,704 | 0.2% | 21 Oct, 2025 |
| 8 | Katherine Schuelke | Svp, Clo Corporate Secretary | 29,063 | 0 | 29,063 | 0.2% | 12 Dec, 2023 |
| 9 | Kian Fatt Chong | Evp Global Operations | 25,093 | 0 | 25,093 | 0.2% | 16 Sep, 2026 |
| 10 | John Christopher Morris | Evp Cto | 22,693 | 0 | 22,693 | 0.2% | 22 Sep, 2026 |
| 11 | Jeffrey D. Fochtman | Svp, Business Marketing | 14,736 | 0 | 14,736 | 0.1% | 14 Sep, 2022 |
| 12 | Dylan G. Haggart | Director | 14,515 | 0 | 14,515 | 0.1% | 21 Oct, 2025 |
| 13 | Judy Bruner | Director | 0 | 14,314 | 14,314 | 0.1% | 21 Oct, 2025 |
| 14 | Michael R Cannon | Director | 13,439 | 0 | 13,439 | 0.1% | 21 Oct, 2025 |
| 15 | Prat Bhatt | Director | 12,869 | 0 | 12,869 | 0.1% | 02 Jun, 2026 |
| 16 | Stephanie Tilenius | Director | 10,664 | 0 | 10,664 | 0.1% | 06 May, 2026 |
| 17 | Shankar Arumugavelu | Director | 6,626 | 0 | 6,626 | 0.0% | 04 Jun, 2026 |
| 18 | Robert A Bruggeworth | Director | 6,591 | 0 | 6,591 | 0.0% | 22 Oct, 2024 |
| 19 | Ban Seng Teh | Evp Chief Commercial Officer | 5,810 | 0 | 5,810 | 0.0% | 16 Sep, 2026 |
| 20 | Yolanda Lee Conyers | Director | 3,351 | 0 | 3,351 | 0.0% | 03 Sep, 2026 |
| 21 | Mark Adams | Director | 2,046 | 0 | 2,046 | 0.0% | 21 Oct, 2025 |
| 22 | Thomas A Szlosek | Director | 357 | 0 | 357 | 0.0% | 12 Nov, 2025 |
| 23 | James Ci Lee | Evp Clo | 347 | 0 | 347 | 0.0% | 26 Aug, 2026 |
| 24 | Jay L Geldmacher | Director | 223 | 0 | 223 | 0.0% | 02 Feb, 2026 |
Each row is that insider’s most recently reported position, from Form 4 filings over the last 60 months — which is why this total does not tie to the quarterly series above, where a quarter counts only the insiders who filed in it. Shares held through a fund or institutional portfolio are counted on the institutional ownership page instead.
| Date | Insider | Position | Transaction | Shares | Price | Value | Shares Held After | Ownership |
|---|---|---|---|---|---|---|---|---|
| 01 Oct, 2026 | William D Mosley | Ceo | Disposed S | 360 | $929.01 | $334.44K | 372,750 | Direct |
| 01 Oct, 2026 | William D Mosley | Ceo | Acquired M | 14,000 | $46.23 | $647.22K | 392,108 | Direct |
| 01 Oct, 2026 | William D Mosley | Ceo | Disposed S | 855 | $930.03 | $795.18K | 371,895 | Direct |
| 01 Oct, 2026 | William D Mosley | Ceo | Disposed S | 360 | $898.10 | $323.31K | 391,748 | Direct |
| 01 Oct, 2026 | William D Mosley | Ceo | Disposed S | 1,665 | $930.99 | $1.55Mn | 370,230 | Direct |
| 01 Oct, 2026 | William D Mosley | Ceo | Disposed S | 517 | $900.46 | $465.54K | 391,231 | Direct |
| 01 Oct, 2026 | William D Mosley | Ceo | Disposed S | 1,320 | $932.04 | $1.23Mn | 368,910 | Direct |
| 01 Oct, 2026 | William D Mosley | Ceo | Disposed S | 440 | $901.49 | $396.65K | 390,791 | Direct |
| 01 Oct, 2026 | William D Mosley | Ceo | Disposed S | 384 | $902.55 | $346.58K | 390,407 | Direct |
| 01 Oct, 2026 | William D Mosley | Ceo | Disposed S | 840 | $933.28 | $783.95K | 368,070 | Direct |
| 01 Oct, 2026 | William D Mosley | Ceo | Disposed S | 696 | $903.36 | $628.74K | 389,711 | Direct |
| 01 Oct, 2026 | William D Mosley | Ceo | Disposed S | 822 | $934.35 | $768.04K | 367,248 | Direct |
| 01 Oct, 2026 | William D Mosley | Ceo | Disposed S | 480 | $904.33 | $434.08K | 389,231 | Direct |
| 01 Oct, 2026 | William D Mosley | Ceo | Disposed S | 640 | $935.15 | $598.50K | 366,608 | Direct |
| 01 Oct, 2026 | William D Mosley | Ceo | Disposed S | 480 | $905.38 | $434.58K | 388,751 | Direct |
| 01 Oct, 2026 | William D Mosley | Ceo | Disposed S | 759 | $936.43 | $710.75K | 365,849 | Direct |
| 01 Oct, 2026 | William D Mosley | Ceo | Disposed S | 579 | $937.33 | $542.71K | 365,270 | Direct |
| 01 Oct, 2026 | William D Mosley | Ceo | Disposed S | 601 | $906.42 | $544.76K | 388,150 | Direct |
| 01 Oct, 2026 | William D Mosley | Ceo | Disposed S | 560 | $907.43 | $508.16K | 387,590 | Direct |
| 01 Oct, 2026 | William D Mosley | Ceo | Disposed S | 640 | $938.32 | $600.52K | 364,630 | Direct |