Maxcyte's three largest insider shareholders as of September 29, 2026 are Partners Master Fund, L.P. Casdin (TenPercentOwner, 10.00Mn shares), Maher Masoud (President And Ceo, 475.00K shares), Stanley C Erck (Director, 428.75K shares).
| # | Insider | Position | Direct | Indirect | Total | Share of Insiders | Last Filed |
|---|---|---|---|---|---|---|---|
| 1 | Partners Master Fund, L.P. Casdin | TenPercentOwner | 10,000,000 | 0 | 10,000,000 | 75.6% | 05 Oct, 2022 |
| 2 | Maher Masoud | President And Ceo | 475,000 | 0 | 475,000 | 3.6% | 31 Mar, 2026 |
| 3 | Stanley C Erck | Director | 428,749 | 0 | 428,749 | 3.2% | 22 Jun, 2026 |
| 4 | Art Mandell | Director | 395,851 | 0 | 395,851 | 3.0% | 13 Jun, 2024 |
| 5 | Douglas Doerfler | President And Ceo | 333,197 | 0 | 333,197 | 2.5% | 06 Dec, 2023 |
| 6 | Richard Douglas | Director | 260,998 | 0 | 260,998 | 2.0% | 22 Jun, 2026 |
| 7 | John Joseph Johnston | Director | 201,581 | 0 | 201,581 | 1.5% | 22 Jun, 2026 |
| 8 | Parmeet Ahuja | Chief Financial Officer | 187,500 | 0 | 187,500 | 1.4% | 17 Apr, 2026 |
| 9 | William W Brooke | Director | 181,300 | 0 | 181,300 | 1.4% | 22 Jun, 2026 |
| 10 | Douglas J Swirsky | Chief Financial Officer | 151,669 | 0 | 151,669 | 1.1% | 19 Mar, 2026 |
| 11 | Ron Holtz | Svp And Cao | 125,251 | 0 | 125,251 | 0.9% | 16 Nov, 2021 |
| 12 | Cynthia Collins | Director | 111,310 | 0 | 111,310 | 0.8% | 22 Jun, 2026 |
| 13 | Yasir B. Al-Wakeel | Director | 80,998 | 0 | 80,998 | 0.6% | 22 Jun, 2026 |
| 14 | Patrick J Balthrop | Director | 80,998 | 0 | 80,998 | 0.6% | 22 Jun, 2026 |
| 15 | Rekha Hemrajani | Director | 70,314 | 0 | 70,314 | 0.5% | 22 Jun, 2026 |
| 16 | David I. Sandoval | General Counsel | 64,219 | 0 | 64,219 | 0.5% | 20 Mar, 2025 |
| 17 | Ali Soleymannezhad | Chief Commercial Officer | 59,439 | 0 | 59,439 | 0.4% | 20 Mar, 2025 |
| 18 | Thomas M. Ross | Evp, Global Sales | 25,000 | 0 | 25,000 | 0.2% | 05 Aug, 2024 |
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 |
|---|---|---|---|---|---|---|---|---|
| 17 Jun, 2026 | Rekha Hemrajani | Director | Acquired A | 30,421 | $0.00 | $0 | 70,314 | Direct |
| 17 Jun, 2026 | Patrick J Balthrop | Director | Acquired A | 30,421 | $0.00 | $0 | 80,998 | Direct |
| 17 Jun, 2026 | Richard Douglas | Director | Acquired A | 30,421 | $0.00 | $0 | 260,998 | Direct |
| 17 Jun, 2026 | John Joseph Johnston | Director | Acquired A | 30,421 | $0.00 | $0 | 201,581 | Direct |
| 17 Jun, 2026 | Stanley C Erck | Director | Acquired A | 30,421 | $0.00 | $0 | 428,749 | Direct |
| 17 Jun, 2026 | William W Brooke | Director | Acquired A | 30,421 | $0.00 | $0 | 181,300 | Direct |
| 17 Jun, 2026 | Yasir B. Al-Wakeel | Director | Acquired A | 30,421 | $0.00 | $0 | 80,998 | Direct |
| 17 Jun, 2026 | Cynthia Collins | Director | Acquired A | 30,421 | $0.00 | $0 | 111,310 | Direct |
| 17 Jun, 2026 | Patrick J Balthrop | Director | Acquired A | 49,579 | $0.00 | $0 | 49,579 | Direct |
| 17 Jun, 2026 | William W Brooke | Director | Acquired A | 49,579 | $0.00 | $0 | 49,579 | Direct |
| 17 Jun, 2026 | Richard Douglas | Director | Acquired A | 49,579 | $0.00 | $0 | 49,579 | Direct |
| 17 Jun, 2026 | Cynthia Collins | Director | Acquired A | 49,579 | $0.00 | $0 | 49,579 | Direct |
| 17 Jun, 2026 | Rekha Hemrajani | Director | Acquired A | 49,579 | $0.00 | $0 | 49,579 | Direct |
| 17 Jun, 2026 | John Joseph Johnston | Director | Acquired A | 49,579 | $0.00 | $0 | 49,579 | Direct |
| 17 Jun, 2026 | Yasir B. Al-Wakeel | Director | Acquired A | 49,579 | $0.00 | $0 | 49,579 | Direct |
| 17 Jun, 2026 | Stanley C Erck | Director | Acquired A | 49,579 | $0.00 | $0 | 49,579 | Direct |
| 15 Apr, 2026 | Parmeet Ahuja | Chief Financial Officer | Acquired A | 187,500 | $0.00 | $0 | 187,500 | Direct |
| 30 Mar, 2026 | Parmeet Ahuja | Chief Financial Officer | Acquired A | 375,000 | $0.00 | $0 | 375,000 | Direct |
| 27 Mar, 2026 | Maher Masoud | President And Ceo | Acquired A | 300,000 | $0.00 | $0 | 475,000 | Direct |
| 27 Mar, 2026 | Maher Masoud | President And Ceo | Acquired A | 600,000 | $0.00 | $0 | 600,000 | Direct |