JBIO's three largest insider shareholders as of June 18, 2026 are Venture Partners X, L.P. Sofinnova (TenPercentOwner, 3.76Mn shares), Maha Katabi (Director, 3.76Mn shares), David S. Grayzel (Director, 3.10Mn shares).
| Holder | Position | Shares (Direct) | Shares (Indirect) | Report Date |
|---|---|---|---|---|
| Ralph Niven | Chief Scientific Officer | 1,609 | 0 | 07 Feb, 2024 |
| Capital Management, L.P. Ra | - | 0 | 1,287,858 | 30 Apr, 2025 |
| George A Eldridge | - | 5,022 | 0 | 14 Jun, 2024 |
| Asset Management, Lp Cormorant | - | 0 | 2,030,691 | 07 Jul, 2021 |
| Venture Partners X, L.P. Sofinnova | - | 3,758,686 | 0 | 06 Jul, 2021 |
| Maha Katabi | - | 0 | 3,758,686 | 06 Jul, 2021 |
| David S. Grayzel | - | 0 | 3,103,879 | 06 Jul, 2021 |
| Bradford D. Dahms | Chief Financial Officer | 37,813 | 0 | 13 Feb, 2026 |
| Funds Management Llc Fairmount | - | 0 | 1,897,677 | 08 Oct, 2025 |
| Venture Fund Xii, L.P. Atlas | - | 2,327,909 | 0 | 19 Jul, 2022 |
| Andrew James King | - | 386,113 | 0 | 13 Feb, 2026 |
| Tom Frohlich | Chief Executive Officer | 86,331 | 0 | 13 Feb, 2026 |
| Hunter Gillies | Chief Medical Officer | 5,602 | 0 | 14 Jun, 2024 |
| Benjamin T Dake | - | 14,252 | 0 | 02 Aug, 2024 |
| Elizabeth Balta | - | 28,125 | 0 | 13 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 |
|---|---|---|---|---|---|---|---|---|
| 12 Feb, 2026 | Andrew James King | Common Stock | A | 41,250 | $0.00 | 386,113 | D | A |
| 12 Feb, 2026 | Tom Frohlich | Common Stock | A | 78,750 | $0.00 | 86,331 | D | A |
| 12 Feb, 2026 | Bradford D. Dahms | Common Stock | A | 37,813 | $0.00 | 37,813 | D | A |
| 12 Feb, 2026 | Elizabeth Balta | Common Stock | A | 28,125 | $0.00 | 28,125 | D | A |
| 12 Feb, 2026 | Andrew James King | Common Stock | A | 41,250 | $0.00 | 386,113 | D | A |
| 12 Feb, 2026 | Tom Frohlich | Stock Option (Right to Buy) | A | 472,500 | $0.00 | 472,500 | D | A |
| 12 Feb, 2026 | Andrew James King | Stock Option (Right to Buy) | A | 247,500 | $0.00 | 247,500 | D | A |
| 12 Feb, 2026 | Elizabeth Balta | Stock Option (Right to Buy) | A | 168,750 | $0.00 | 168,750 | D | A |
| 12 Feb, 2026 | Andrew James King | Stock Option (Right to Buy) | A | 247,500 | $0.00 | 247,500 | D | A |
| 12 Feb, 2026 | Bradford D. Dahms | Stock Option (Right to Buy) | A | 226,875 | $0.00 | 226,875 | D | A |
| 06 Oct, 2025 | Funds Management Llc Fairmount | Common Stock | A | 1,333,126 | $9.14 | 1,897,677 | I | A |
| 06 Oct, 2025 | Funds Management Llc Fairmount | Pre-Funded Warrant (Right to Buy) | A | 855,047 | $9.14 | 855,047 | I | A |
| 14 Jul, 2025 | Bradford D. Dahms | Stock Option (Right to Buy) | A | 526,000 | $0.00 | 526,000 | D | A |
| 16 May, 2025 | Tom Frohlich | Common Stock | A | 6,000 | $7.40 | 6,000 | D | P |
| 29 Apr, 2025 | Erin Lavelle | Stock Option (Right to Buy) | A | 23,017 | $0.00 | 23,017 | D | A |
| 29 Apr, 2025 | Lawrence Otto Klein | Stock Option (Right to Buy) | A | 23,017 | $0.00 | 23,017 | D | A |
| 29 Apr, 2025 | Funds Management Llc Fairmount | Stock Option (Right to Buy) | A | 23,017 | $0.00 | 23,017 | D | A |
| 29 Apr, 2025 | Eric Dobmeier | Stock Option (Right to Buy) | A | 23,017 | $0.00 | 23,017 | D | A |
| 29 Apr, 2025 | Christopher W. Cain | Stock Option (Right to Buy) | A | 23,017 | $0.00 | 23,017 | D | A |
| 28 Apr, 2025 | Capital Management, L.P. Ra | Common Stock | A | 1,062,326 | - | 1,287,858 | I | J |