As of September 12, 2026, the three largest insider holders of STX are Holdings, L.P. Valueact (Director, 13.44Mn shares), Holdings, L.P. Valueact (Director, 13.44Mn shares), Holdings, L.P. Valueact (Director, 13.44Mn 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 | 94.0% | 22 Feb, 2022 |
| 2 | William D Mosley | Ceo | 297,548 | 0 | 297,548 | 2.1% | 11 Sep, 2026 |
| 3 | Stephen J Luczo | Executive Chairman Cob | 0 | 225,941 | 225,941 | 1.6% | 08 Mar, 2022 |
| 4 | Edward J Zander | Director | 0 | 41,357 | 41,357 | 0.3% | 22 Oct, 2021 |
| 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 | Gianluca Romano | Evp Cfo | 29,620 | 0 | 29,620 | 0.2% | 11 Sep, 2026 |
| 9 | Katherine Schuelke | Svp, Clo Corporate Secretary | 29,063 | 0 | 29,063 | 0.2% | 12 Dec, 2023 |
| 10 | John Christopher Morris | Evp Cto | 16,019 | 0 | 16,019 | 0.1% | 11 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 | Kian Fatt Chong | Evp Global Operations | 9,945 | 0 | 9,945 | 0.1% | 11 Sep, 2026 |
| 18 | Shankar Arumugavelu | Director | 6,626 | 0 | 6,626 | 0.0% | 04 Jun, 2026 |
| 19 | Robert A Bruggeworth | Director | 6,591 | 0 | 6,591 | 0.0% | 22 Oct, 2024 |
| 20 | Ban Seng Teh | Evp Chief Commercial Officer | 5,810 | 0 | 5,810 | 0.0% | 11 Sep, 2026 |
| 21 | Yolanda Lee Conyers | Director | 3,351 | 0 | 3,351 | 0.0% | 03 Sep, 2026 |
| 22 | Mark Adams | Director | 2,046 | 0 | 2,046 | 0.0% | 21 Oct, 2025 |
| 23 | Thomas A Szlosek | Director | 357 | 0 | 357 | 0.0% | 12 Nov, 2025 |
| 24 | James Ci Lee | Evp Clo | 347 | 0 | 347 | 0.0% | 26 Aug, 2026 |
| 25 | 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 |
|---|---|---|---|---|---|---|---|---|
| 09 Sep, 2026 | Gianluca Romano | Evp Cfo | Acquired M | 959 | $0.00 | $0 | 29,453 | Direct |
| 09 Sep, 2026 | John Christopher Morris | Evp Cto | Acquired M | 500 | $0.00 | $0 | 15,960 | Direct |
| 09 Sep, 2026 | Kian Fatt Chong | Evp Global Operations | Acquired M | 202 | $0.00 | $0 | 9,566 | Direct |
| 09 Sep, 2026 | William D Mosley | Ceo | Acquired M | 2,815 | $0.00 | $0 | 297,983 | Direct |
| 09 Sep, 2026 | Ban Seng Teh | Evp Chief Commercial Officer | Acquired M | 600 | $0.00 | $0 | 5,810 | Direct |
| 10 Sep, 2026 | William D Mosley | Ceo | Disposed S | 1,534 | $862.13 | $1.32Mn | 296,449 | Direct |
| 10 Sep, 2026 | Gianluca Romano | Evp Cfo | Disposed S | 523 | $862.13 | $450.46K | 28,931 | Direct |
| 10 Sep, 2026 | John Christopher Morris | Evp Cto | Disposed S | 253 | $862.13 | $218.12K | 15,707 | Direct |
| 09 Sep, 2026 | Kian Fatt Chong | Evp Global Operations | Acquired M | 379 | $0.00 | $0 | 9,945 | Direct |
| 09 Sep, 2026 | Ban Seng Teh | Evp Chief Commercial Officer | Acquired M | 663 | $0.00 | $0 | 6,473 | Direct |
| 09 Sep, 2026 | John Christopher Morris | Evp Cto | Acquired M | 631 | $0.00 | $0 | 16,338 | Direct |
| 09 Sep, 2026 | Gianluca Romano | Evp Cfo | Acquired M | 1,515 | $0.00 | $0 | 30,446 | Direct |
| 09 Sep, 2026 | Kian Fatt Chong | Evp Global Operations | Disposed M | 202 | $0.00 | $0 | 0 | Direct |
| 09 Sep, 2026 | William D Mosley | Ceo | Acquired M | 2,415 | $0.00 | $0 | 298,864 | Direct |
| 10 Sep, 2026 | Ban Seng Teh | Evp Chief Commercial Officer | Disposed S | 663 | $860.09 | $570.24K | 5,810 | Direct |
| 09 Sep, 2026 | Ban Seng Teh | Evp Chief Commercial Officer | Disposed M | 600 | $0.00 | $0 | 0 | Direct |
| 09 Sep, 2026 | Kian Fatt Chong | Evp Global Operations | Disposed M | 379 | $0.00 | $0 | 3,033 | Direct |
| 10 Sep, 2026 | Gianluca Romano | Evp Cfo | Disposed S | 826 | $862.13 | $711.69K | 29,620 | Direct |
| 10 Sep, 2026 | John Christopher Morris | Evp Cto | Disposed S | 319 | $862.14 | $275.24K | 16,019 | Direct |
| 10 Sep, 2026 | William D Mosley | Ceo | Disposed S | 1,316 | $862.14 | $1.13Mn | 297,548 | Direct |