MBX's three largest insider shareholders as of June 09, 2026 are Patrick J Heron (Director, 5.22Mn shares), Patrick J Heron (Director, 4.55Mn shares), Life Sciences X, L.P. Frazier (TenPercentOwner, 4.55Mn shares).
| Holder | Position | Shares (Direct) | Shares (Indirect) | Report Date |
|---|---|---|---|---|
| Advisors Llc Orbimed | - | 0 | 3,812,215 | 17 Sep, 2024 |
| James M Cornelius | - | 102,082 | 0 | 17 Sep, 2024 |
| Scott D Sandell | - | 0 | 3,614,486 | 17 Sep, 2024 |
| Forest Baskett | - | 0 | 3,614,486 | 17 Sep, 2024 |
| Carl L Gordon | - | 0 | 3,812,215 | 17 Sep, 2024 |
| Edward T Mathers | - | 0 | 3,614,486 | 17 Sep, 2024 |
| Patrick J Heron | - | 0 | 5,219,440 | 30 Sep, 2025 |
| Ora H. Pescovitz | - | 24,329 | 0 | 10 Apr, 2025 |
| Steven L. Hoerter | - | 0 | 20,000 | 20 Oct, 2025 |
| Paul Edward Walker | - | 0 | 3,614,486 | 17 Sep, 2024 |
| Anthony A. Jr. Florence | - | 0 | 3,614,486 | 17 Sep, 2024 |
| Ali Behbahani | - | 0 | 3,614,486 | 17 Sep, 2024 |
| Mohamad Makhzoumi | - | 0 | 3,614,486 | 17 Sep, 2024 |
| Tiba Aynechi | - | 0 | 2,136,335 | 17 Sep, 2024 |
| P. Kent Hawryluk | President Ceo | 728,274 | 0 | 27 Feb, 2026 |
| Richard Bartram | Chief Financial Officer | 15,000 | 0 | 03 Feb, 2026 |
| Carmen Chang | - | 0 | 3,614,486 | 17 Sep, 2024 |
| Enterprise Associates 17, L.P. New | - | 3,614,486 | 0 | 17 Sep, 2024 |
| Life Sciences X, L.P. Frazier | - | 4,552,774 | 0 | 17 Sep, 2024 |
| Rick Yang | - | 0 | 3,614,486 | 17 Sep, 2024 |
| Biomedical Innovation Master Investors (Cayman) Ii L.P. Wellington | - | 1,790,122 | 0 | 17 Sep, 2024 |
| Salomon Azoulay | Chief Medical Officer | 15,000 | 0 | 03 Feb, 2026 |
* Please note that the shares above only reflect shares from the fund portfolio and the institutional portfolio. Shares from the personal portfolio are excluded from this Institutional Ownership Page. See these insiders' latest transactions here on Insider Page.
| Transaction Date | Insider Name | Security Class | Transaction Type | Shares Traded | Price | Shares Remaining | Ownership | Code |
|---|---|---|---|---|---|---|---|---|
| 13 Mar, 2026 | P. Kent Hawryluk | Common Stock | A | 18,500 | $28.41 | 486,777 | I | P |
| 26 Feb, 2026 | P. Kent Hawryluk | Common Stock | A | 28,768 | $16.00 | 728,274 | D | M |
| 26 Feb, 2026 | P. Kent Hawryluk | Stock option (right to buy) | D | 28,768 | $0.00 | 91,668 | D | M |
| 02 Feb, 2026 | P. Kent Hawryluk | Common Stock | A | 35,250 | $0.00 | 699,506 | D | A |
| 02 Feb, 2026 | Richard Bartram | Common Stock | A | 15,000 | $0.00 | 15,000 | D | A |
| 02 Feb, 2026 | Salomon Azoulay | Common Stock | A | 15,000 | $0.00 | 15,000 | D | A |
| 02 Feb, 2026 | Salomon Azoulay | Stock option (right to buy) | A | 70,000 | $0.00 | 70,000 | D | A |
| 02 Feb, 2026 | Richard Bartram | Stock option (right to buy) | A | 70,000 | $0.00 | 70,000 | D | A |
| 02 Feb, 2026 | P. Kent Hawryluk | Stock option (right to buy) | A | 164,500 | $0.00 | 164,500 | D | A |
| 20 Jan, 2026 | Laurie Stelzer | Stock option (right to buy) | A | 32,000 | $0.00 | 32,000 | D | A |
| 22 Nov, 2025 | Steven L. Hoerter | Stock option (right to buy) | A | 8,000 | $0.00 | 8,000 | D | A |
| 06 Nov, 2025 | Steven L. Hoerter | Stock option (right to buy) | A | 100,000 | $0.00 | 100,000 | D | A |
| 24 Oct, 2025 | P. Kent Hawryluk | Common Stock | A | 182,859 | $3.25 | 664,256 | D | M |
| 24 Oct, 2025 | P. Kent Hawryluk | Stock option (right to buy) | D | 182,859 | $0.00 | 129,708 | D | M |
| 20 Oct, 2025 | P. Kent Hawryluk | Common Stock | A | 20,000 | $13.64 | 468,277 | I | P |
| 17 Oct, 2025 | Steven L. Hoerter | Common Stock | A | 20,000 | $13.25 | 20,000 | I | P |
| 26 Sep, 2025 | Patrick J Heron | Common Stock | A | 666,666 | $18.00 | 5,219,440 | I | P |
| 05 Jun, 2025 | Patrick J Heron | Stock option (right to buy) | A | 16,000 | $0.00 | 16,000 | D | A |
| 05 Jun, 2025 | Tiba Aynechi | Stock option (right to buy) | A | 16,000 | $0.00 | 16,000 | D | A |
| 05 Jun, 2025 | Steven Ryder | Stock option (right to buy) | A | 16,000 | $0.00 | 16,000 | D | A |