As of August 04, 2026, the three largest insider holders of ONTO are Michael P Plisinski (Chief Executive Officer, 179.24K shares), Christopher A Seams (Director, 37.75K shares), Rollin Kocher (Svp, Sales And Marketing, 33.90K shares).
| # | Insider | Position | Direct | Indirect | Total | Share of Insiders | Last Filed |
|---|---|---|---|---|---|---|---|
| 1 | Michael P Plisinski | Chief Executive Officer | 179,242 | 0 | 179,242 | 38.1% | 04 Mar, 2026 |
| 2 | Christopher A Seams | Director | 37,752 | 0 | 37,752 | 8.0% | 23 May, 2025 |
| 3 | Rollin Kocher | Svp, Sales And Marketing | 33,896 | 0 | 33,896 | 7.2% | 08 Sep, 2021 |
| 4 | Ido Dolev | Evp, Prod Solutions Grp | 26,536 | 0 | 26,536 | 5.6% | 04 Mar, 2026 |
| 5 | Steven R Roth | Sr Vp Cfo | 23,043 | 0 | 23,043 | 4.9% | 13 Feb, 2022 |
| 6 | Yoon Ah Oh | Svp, Gen Counsel Corp Sec | 21,640 | 0 | 21,640 | 4.6% | 04 Mar, 2026 |
| 7 | Leo Berlinghieri | Director | 20,210 | 0 | 20,210 | 4.3% | 23 May, 2024 |
| 8 | Srinivas Vedula | Svp, Customer Success | 18,730 | 0 | 18,730 | 4.0% | 05 Mar, 2025 |
| 9 | Ramil Yaldaei | Chief Operating Officer | 18,436 | 0 | 18,436 | 3.9% | 04 Mar, 2026 |
| 10 | Shirley Chen | Svp Customer Success | 15,517 | 0 | 15,517 | 3.3% | 04 Mar, 2026 |
| 11 | Mark Slicer | Chief Financial Officer | 13,640 | 0 | 13,640 | 2.9% | 19 May, 2025 |
| 12 | David Brian Miller | Director | 11,931 | 0 | 11,931 | 2.5% | 23 May, 2025 |
| 13 | Ju Jin | Svp Gm, Ibu | 10,254 | 0 | 10,254 | 2.2% | 16 Jun, 2023 |
| 14 | Robert Fiordalice | Svp Gm, Metrology Bu | 8,763 | 0 | 8,763 | 1.9% | 05 Mar, 2024 |
| 15 | James Harlow | Chief Operating Officer | 8,586 | 0 | 8,586 | 1.8% | 15 Feb, 2023 |
| 16 | May Su | Director | 7,223 | 0 | 7,223 | 1.5% | 23 May, 2025 |
| 17 | Stephen Douglas Kelley | Director | 5,623 | 0 | 5,623 | 1.2% | 23 May, 2025 |
| 18 | Bruce C Rhine | Director | 3,500 | 0 | 3,500 | 0.7% | 17 Feb, 2022 |
| 19 | D Mayson Brooks | Vice President Gm, Ibu | 3,025 | 0 | 3,025 | 0.6% | 04 Sep, 2024 |
| 20 | Susan D Lynch | Director | 2,923 | 0 | 2,923 | 0.6% | 23 May, 2025 |
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 |
|---|---|---|---|---|---|---|---|---|
| 02 Mar, 2026 | Ramil Yaldaei | Chief Operating Officer | Acquired A | 7,683 | $0.00 | $0 | 19,051 | Direct |
| 02 Mar, 2026 | Yoon Ah Oh | Svp, Gen Counsel Corp Sec | Acquired A | 2,408 | $0.00 | $0 | 22,057 | Direct |
| 02 Mar, 2026 | Ramil Yaldaei | Chief Operating Officer | Acquired A | 7,683 | $0.00 | $0 | 19,051 | Direct |
| 02 Mar, 2026 | Ramil Yaldaei | Chief Operating Officer | Acquired A | 7,683 | $0.00 | $0 | 19,051 | Direct |
| 02 Mar, 2026 | Ido Dolev | Evp, Prod Solutions Grp | Acquired A | 3,440 | $0.00 | $0 | 27,355 | Direct |
| 02 Mar, 2026 | Shirley Chen | Svp Customer Success | Acquired A | 2,523 | $0.00 | $0 | 15,517 | Direct |
| 02 Mar, 2026 | Michael P Plisinski | Chief Executive Officer | Acquired A | 14,479 | $0.00 | $0 | 182,984 | Direct |
| 03 Mar, 2026 | Michael P Plisinski | Chief Executive Officer | Disposed F | 3,742 | $207.50 | $776.47K | 179,242 | Direct |
| 03 Mar, 2026 | Yoon Ah Oh | Svp, Gen Counsel Corp Sec | Disposed F | 417 | $207.50 | $86.53K | 21,640 | Direct |
| 03 Mar, 2026 | Ramil Yaldaei | Chief Operating Officer | Disposed F | 615 | $207.50 | $127.61K | 18,436 | Direct |
| 02 Mar, 2026 | Shirley Chen | Svp Customer Success | Acquired A | 1,261 | $0.00 | $0 | 1,261 | Direct |
| 03 Mar, 2026 | Ramil Yaldaei | Chief Operating Officer | Disposed F | 615 | $207.50 | $127.61K | 18,436 | Direct |
| 03 Mar, 2026 | Ido Dolev | Evp, Prod Solutions Grp | Disposed F | 819 | $207.50 | $169.94K | 26,536 | Direct |
| 03 Mar, 2026 | Ramil Yaldaei | Chief Operating Officer | Disposed F | 615 | $207.50 | $127.61K | 18,436 | Direct |
| 02 Mar, 2026 | Ramil Yaldaei | Chief Operating Officer | Acquired A | 1,548 | $0.00 | $0 | 1,548 | Direct |
| 02 Mar, 2026 | Ramil Yaldaei | Chief Operating Officer | Acquired A | 1,548 | $0.00 | $0 | 1,548 | Direct |
| 02 Mar, 2026 | Yoon Ah Oh | Svp, Gen Counsel Corp Sec | Acquired A | 1,204 | $0.00 | $0 | 1,204 | Direct |
| 02 Mar, 2026 | Ramil Yaldaei | Chief Operating Officer | Acquired A | 1,548 | $0.00 | $0 | 1,548 | Direct |
| 02 Mar, 2026 | Michael P Plisinski | Chief Executive Officer | Acquired A | 7,239 | $0.00 | $0 | 7,239 | Direct |
| 02 Mar, 2026 | Shirley Chen | Svp Customer Success | Acquired A | 1,261 | $0.00 | $0 | 1,261 | Direct |