Mereo BioPharma Group plc has 12 Schedule 13D or 13G filings on record since 2025-08-14. 2 holders' latest filing reports 5% or more of ordinary shares. Each figure below is the holder's own, as filed, with the filing linked.
Holders
| Holder | Percent | Shares | Latest | Event date |
|---|---|---|---|---|
| 683 Capital Management, LLC | 8.18% | 65,083,815 | SCHEDULE 13G, 2026-01-06 | 2025-12-29 |
| Bank Of America Corp | 5.1% | 40,976,460 | SCHEDULE 13G, 2026-05-14 | 2026-03-31 |
| Mangrove Partners IM, LLC | 4.9% | 38,952,900 | SCHEDULE 13G/A, 2025-11-14 | 2025-09-30 |
| EcoR1 Capital, LLC | 0.6% | 5,000,000 | SCHEDULE 13G/A, 2026-08-14 | 2026-06-30 |
| Janus Henderson Group Plc | 0% | 0 | SCHEDULE 13G/A, 2026-02-17 | 2025-12-31 |
| Frazier Life Sciences Public Fund, L.P. | 0% | 0 | SCHEDULE 13G/A, 2026-02-13 | 2025-12-31 |
| Northpond Ventures, LP | 0% | 0 | SCHEDULE 13G/A, 2026-02-17 | 2025-12-31 |
Timeline
| Filed | Holder | Percent | Filing |
|---|---|---|---|
| 2025-08-14 | Janus Henderson Group Plc | 11.1% | SCHEDULE 13G/A |
| 2025-08-14 | Frazier Life Sciences Public Fund, L.P. | 4.1% | SCHEDULE 13G/A |
| 2025-11-14 | Mangrove Partners IM, LLC | 4.9% | SCHEDULE 13G/A |
| 2025-11-14 | Janus Henderson Group Plc | 10.2% | SCHEDULE 13G/A |
| 2026-01-06 | 683 Capital Management, LLC | 8.18% | SCHEDULE 13G |
| 2026-01-09 | EcoR1 Capital, LLC | 9.4% | SCHEDULE 13G |
| 2026-02-13 | Frazier Life Sciences Public Fund, L.P. | 0% | SCHEDULE 13G/A |
| 2026-02-17 | Janus Henderson Group Plc | 0% | SCHEDULE 13G/A |
| 2026-02-17 | Northpond Ventures, LP | 0% | SCHEDULE 13G/A |
| 2026-05-14 | Bank Of America Corp | 5.1% | SCHEDULE 13G |
| 2026-05-15 | EcoR1 Capital, LLC | 8.4% | SCHEDULE 13G/A |
| 2026-08-14 | EcoR1 Capital, LLC | 0.6% | SCHEDULE 13G/A |
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Where this comes from
Anyone who comes to own more than 5% of a class of a listed company's voting shares has to tell the SEC. A holder who may seek to change or influence the company files Schedule 13D, and has to say in Item 4, "Purpose of Transaction", what it intends to do. A holder with no such intent, such as many index and passive funds, may file the shorter Schedule 13G. Both are amended when the stake changes, including when it falls below 5%.
Every row here is one of those filings, linked to the filing itself. Percentages and share counts are exactly as the holder filed them, for the holder the filing names; an amendment showing a lower figure is shown as filed. Item 4 text is quoted word for word. Where a 13D's Item 4 contains a sentence stating a definite intent to influence the company, that sentence is marked and quoted; the page does not describe the holder or its motives beyond the words it filed. Nothing here is investment advice.