MREO · Mereo BioPharma Group plc · Shareholders & Ownership
Market Cap
$47.12M
Shares
159.69M
Volume · Oct 21
330.19K
Avg daily vol (3M)
3.99M
Every disclosed holder of MREO in one list: 13F institutions, Schedule 13D and 13G filers, insiders (Forms 3, 4 and 5) and registered funds, each from its own latest filing. Holders nest by CIK and SEC reporting links, never by name, and each is summed once.
Who Owns MREO
13F quarter Sep 30, 2026, combined view: filers that have not filed yet carry their Jun 30, 2026 positions| Holder group | Shares | % Out |
|---|---|---|
| Institutional (13F) | 56,607,448 | 7.09% |
| Insiders (Forms 3, 4, 5) | 0 | 0.00% |
| 13D/G-only blocks | 128,687,745 | 16.12% |
| Remaining | 613,159,671 | 76.79% |
| Registered funds (N-PORT, not summed) | 241,806 | 0.03% |
Shares outstanding: 798,454,864, the issuer's latest cover-page count restated onto today's split basis.
13D/G-only counts each filer's latest 13D or 13G that no 13F report of the listing contains, that names no 13F filer and that no counted insider files. Funds are never summed: their shares sit inside their advisers' 13F reports.
Holders of MREO
| # | Holder | Shares | As of | Notes |
|---|---|---|---|---|
| 1 |
ADAGE CAPITAL PARTNERS GP, L.L.C.
13G
CIK 1165408 · Registered investment adviser · Dec 31, 2024
Rule 13d-1(b), qualified institution
|
43,575,065 | ||
| 2 |
MANGROVE PARTNERS IM, LLC
13G
CIK 1535392 · Registered investment adviser · Sep 30, 2025
Rule 13d-1(b), qualified institution
|
38,952,900 | ||
| 3 |
Rock Springs Capital Management LP
13G
CIK 1595725 · Registered investment adviser · Mar 31, 2025
Rule 13d-1(c), passive investor
|
33,421,235 | ||
| 4 |
Rubric Capital Management LP
13F
CIK 1687509 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
|
15,307,347 | ||
| 5 |
683 Capital Management, LLC
13F
CIK 1404574 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
|
11,777,856 | ||
| 6 |
Adage Capital Management, L.P.
13G
CIK 1535978 · Investment adviser · Mar 31, 2025
Rule 13d-1(b), qualified institution
|
8,503,780 | ||
| 7 |
BANK OF AMERICA CORP /DE/
13F
CIK 70858 · Bank · Jun 30, 2026
carried, not yet filed for the newest quarter
|
8,195,281 | ||
| 8 |
Defilade Capital Management, L.P.
13F
CIK 2088557 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
|
7,558,756 | ||
| 9 |
Soleus Capital Management, L.P.
13G
CIK 1955982 · Unknown · Sep 30, 2024
Rule 13d-1(c), passive investor
|
4,234,765 | ||
| 10 |
Newtyn Management, LLC
13F
CIK 1569241 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
|
3,000,000 | ||
| 11 |
Tejara Capital Ltd
13F
CIK 1879713 · Exempt reporting adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
|
2,037,520 | ||
| 12 |
|
1,447,627 | ||
| 13 |
TWO SIGMA INVESTMENTS, LP
13F
CIK 1179392 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
|
1,319,241 | ||
| 14 |
EcoR1 Capital, LLC
13F
CIK 1587114 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
|
1,000,000 | ||
| 14.1 |
EcoR1 Capital, LLC
13G
CIK 1587114 · Registered investment adviser · Jun 30, 2026
Rule 13d-1(b), qualified institution, not summed
|
5,000,000 | ||
| 15 |
JANE STREET GROUP, LLC
13F
CIK 1595888 · Unknown · Jun 30, 2026
carried, not yet filed for the newest quarter
|
774,944 | ||
| 16 |
Ishara Investments LP
13F
CIK 2111609 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
|
768,750 | ||
| 17 |
Wealthspire Advisors, LLC
13F
CIK 1646247 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
|
765,000 | ||
| 18 |
CITADEL ADVISORS LLC
13F
CIK 1423053 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
|
444,158 | ||
| 19 |
Rangeley Capital, LLC
13F
CIK 1517796 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
|
329,200 | ||
| 20 |
SUSQUEHANNA INTERNATIONAL GROUP, LLP
13F
CIK 1446194 · Unknown · Jun 30, 2026
carried, not yet filed for the newest quarter
|
213,270 | ||
| 21 |
MARSHALL WACE, LLP
13F
CIK 1318757 · Exempt reporting adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
|
179,884 | ||
| 22 |
XTX Topco Ltd
13F
CIK 1828301 · Unknown · Jun 30, 2026
carried, not yet filed for the newest quarter
|
174,481 | ||
| 23 |
GROUP ONE TRADING LLC
13F
CIK 932540 · Broker-dealer · Jun 30, 2026
carried, not yet filed for the newest quarter
|
167,515 | ||
| 24 |
|
134,772 | ||
| 24.1 |
State Street(R) SPDR(R) S&P(R) International Small Cap ETF
Fund
S000014039 · Registered fund · Jun 30, 2026
SPDR INDEX SHARES FUNDS, not summed
|
134,772 | ||
| 25 |
NOMURA HOLDINGS INC
13F
CIK 1163653 · Unknown · Jun 30, 2026
carried, not yet filed for the newest quarter
|
104,361 | ||
| 26 |
James J. Burns & Company, LLC
13F
CIK 1949059 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
|
95,400 | ||
| 27 |
|
93,750 | ||
| 28 |
Fidelity Nasdaq Composite Index Fund
Fund
S000055366 · Registered fund · May 31, 2026
Fidelity Concord Street Trust, not summed
|
92,534 | ||
| 29 |
GOLDMAN SACHS GROUP INC
13F
CIK 886982 · Holding company · Jun 30, 2026
carried, not yet filed for the newest quarter
|
85,180 | ||
| 30 |
JMN Financial LLC
13F
CIK 2113267 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
|
76,748 | ||
| 31 |
BlackRock, Inc.
13F
CIK 2012383 · Holding company · Jun 30, 2026
carried, not yet filed for the newest quarter
|
69,678 | ||
| 32 |
Virtu Financial LLC
13F
CIK 1533964 · Unknown · Jun 30, 2026
carried, not yet filed for the newest quarter
|
61,285 | ||
| 33 |
JPMORGAN CHASE & CO
13F
CIK 19617 · Bank · Jun 30, 2026
carried, not yet filed for the newest quarter
|
58,531 | ||
| 34 |
RENAISSANCE TECHNOLOGIES LLC
13F
CIK 1037389 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
|
52,100 | ||
| 35 |
Significant Wealth Partners LLC
13F
CIK 1964680 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
|
32,677 | ||
| 36 |
Clear Harbor Asset Management, LLC
13F
CIK 1511857 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
|
32,000 | ||
| 37 |
RHUMBLINE ADVISERS
13F
CIK 1115418 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
|
26,784 | ||
| 38 |
Centiva Capital, LP
13F
CIK 1692507 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
|
25,000 | ||
| 39 |
Engineers Gate Manager LP
13F
CIK 1620220 · Unknown · Jun 30, 2026
carried, not yet filed for the newest quarter
|
23,953 | ||
| 40 |
SIMPLEX TRADING, LLC
13F
CIK 1488542 · Unknown · Jun 30, 2026
carried, not yet filed for the newest quarter
|
18,780 | ||
| 41 |
NFSG Corp
13F
CIK 1879757 · Registered investment adviser · Sep 30, 2026
|
18,750 | ||
| 42 |
OneDigital Investment Advisors LLC
13F
CIK 1690370 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
|
18,300 | ||
| 43 |
MORGAN STANLEY
13F
CIK 895421 · Holding company · Jun 30, 2026
carried, not yet filed for the newest quarter
|
16,731 | ||
| 44 |
IHT Wealth Management, LLC
13F
CIK 1697490 · Unknown · Jun 30, 2026
carried, not yet filed for the newest quarter
|
15,000 | ||
| 45 |
Blackstone Alternative Multi-Strategy Fund
Fund
S000045538 · Registered fund · Jun 30, 2026
Blackstone Alternative Investment Funds, not summed
|
14,500 | ||
| 46 |
TWO SIGMA SECURITIES, LLC
13F
CIK 1450144 · Unknown · Jun 30, 2026
carried, not yet filed for the newest quarter
|
12,900 | ||
| 47 |
J. Safra Sarasin Holding AG
13F
CIK 1890222 · Unknown · Jun 30, 2026
carried, not yet filed for the newest quarter
|
12,841 | ||
| 48 |
SG Americas Securities, LLC
13F
CIK 1313360 · Unknown · Jun 30, 2026
carried, not yet filed for the newest quarter
|
12,802 | ||
| 49 |
MML INVESTORS SERVICES, LLC
13F
CIK 701059 · Unknown · Jun 30, 2026
carried, not yet filed for the newest quarter
|
12,200 | ||
| 50 |
Astoria Portfolio Advisors LLC.
13F
CIK 1931642 · Registered investment adviser · Jun 30, 2026
carried, not yet filed for the newest quarter
|
10,000 |
Shares are restated onto today's split basis. Change compares each row with the same holder's previous filing in the same source; a dash means there is none to compare. Nested 13D/G, insider and fund rows are not summed, since a 13F report already holds them.
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