Maxcyte's three largest insider shareholders as of September 09, 2026 are Partners Master Fund, L.P. Casdin (TenPercentOwner, 10.00Mn shares), Partners Master Fund, L.P. Casdin (TenPercentOwner, 10.00Mn shares), Partners Master Fund, L.P. Casdin (TenPercentOwner, 10.00Mn 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 | Stanley C Erck | Director | Acquired A | 30,421 | $0.00 | $0 | 428,749 | Direct |
| 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 | John Joseph Johnston | Director | Acquired A | 30,421 | $0.00 | $0 | 201,581 | 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 | Richard Douglas | Director | Acquired A | 30,421 | $0.00 | $0 | 260,998 | 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 | Cynthia Collins | 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 | Rekha Hemrajani | 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 |
| 17 Jun, 2026 | Patrick J Balthrop | 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 | 300,000 | $0.00 | $0 | 475,000 | Direct |