As of November 6, 2026, one holder's latest Schedule 13D or 13G filing report owning 5% or more of Mereo BioPharma Group plc. The largest reported stake is 683 Capital Management, LLC's, at 8.18%. 13 filings are on record since August 14, 2025 (Schedule 13G, January 6, 2026).
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Key facts
- · Reporting person: Bank Of America Corp · Sole voting: 0 · Shared voting: 26,889,300 · Sole dispositive: 0 · Shared dispositive: 26,889,300 · SCHEDULE 13G/A, 2026-10-28
- · Reporting person: EcoR1 Capital, LLC · Sole voting: 0 · Shared voting: 5,000,000 · Sole dispositive: 0 · Shared dispositive: 5,000,000 · SCHEDULE 13G/A, 2026-08-14
- · Holder: EcoR1 Capital, LLC · Percent: 8.4% · SCHEDULE 13G/A
- · Holder: Bank Of America Corp · Percent: 5.1% · SCHEDULE 13G
- · Holder: Janus Henderson Group Plc · Percent: 0% · SCHEDULE 13G/A
Mereo BioPharma Group plc has 13 Schedule 13D or 13G filings on record since 2025-08-14. 1 holder's 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 |
| Mangrove Partners IM, LLC | 4.9% | 38,952,900 | SCHEDULE 13G/A, 2025-11-14 | 2025-09-30 |
| Bank Of America Corp | 3.4% | 26,889,300 | SCHEDULE 13G/A, 2026-10-28 | 2026-09-30 |
| 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 |
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More on Mereo BioPharma Group plc and the records around it.
Mereo BioPharma Group plc elsewhere on the record
Companies that share a holder
- Mangrove Partners IM, LLC also filed stake reports on 2 other companies: ChampionsGate Acquisition Corp (Jul 2026), ClearThink 1 Acquisition Corp. (Jul 2026)
- 683 Capital Management, LLC also filed stake reports on 10 other companies: Perceptive Capital Solutions Corp (Aug 2026), Gossamer Bio, Inc. (Jun 2026), FRACTYL HEALTH, INC. (May 2026)
- EcoR1 Capital, LLC also filed stake reports on 20 other companies: Alto Neuroscience, Inc. (Jul 2026), Fulcrum Therapeutics, Inc. (Jun 2026), Eloxx Pharmaceuticals, Inc. (Jun 2026)
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Voting and dispositive power, as filed
| Reporting person | Sole voting | Shared voting | Sole dispositive | Shared dispositive | Filing |
|---|---|---|---|---|---|
| Bank Of America Corp | 0 | 26,889,300 | 0 | 26,889,300 | SCHEDULE 13G/A, 2026-10-28 |
| EcoR1 Capital, LLC | 0 | 5,000,000 | 0 | 5,000,000 | SCHEDULE 13G/A, 2026-08-14 |
| Oleg Nodelman | 0 | 5,000,000 | 0 | 5,000,000 | SCHEDULE 13G/A, 2026-08-14 |
| EcoR1 Capital Fund Qualified, L.P. | 0 | 4,732,750 | 0 | 4,732,750 | SCHEDULE 13G/A, 2026-08-14 |
The latest filing identifies Mereo BioPharma Group plc by CUSIP G6014T100 and gives its principal executive office as ONE CAVENDISH PLACE, FOURTH FLOOR, LONDON (SCHEDULE 13G/A, 2026-10-28).
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 |
| 2026-10-28 | Bank Of America Corp | 3.4% | SCHEDULE 13G/A |
Questions about who owns Mereo BioPharma Group plc
Who owns Mereo BioPharma Group plc?
On this page, one holder's latest ownership filing reports 5% or more of Mereo BioPharma Group plc: 683 Capital Management, LLC (8.18%, Schedule 13G, filed 2026-01-06).
When did 683 Capital Management, LLC buy into Mereo BioPharma Group plc?
The filings give report dates, not purchase dates. The earliest filing from 683 Capital Management, LLC on this page is the Schedule 13G, filed 2026-01-06, reporting 8.18%.
Is this an audit or a full list?
Neither. The ownership list on this page covers only Schedule 13D and 13G filings, which holders make once they own 5% or more of a class of shares (an amendment can report a stake that has since fallen below 5%); 13 such filings are shown here. It is not an audit and not a full cap table: holders who never reached 5% are not listed, and a stake can change after its latest filing.
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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.