MREO · Mereo BioPharma Group plc

$0.25 -0.02 (-7.17%) At close · Aug 28

Market Cap

$40.32M

159.69M

Institutional ownership from SEC Form 13F filings. Investment managers with more than $100 million in U.S. equities must disclose their positions every quarter, within 45 days of quarter-end, so the holdings shown can lag the market by up to a quarter.

Quarter:

Holders: 61

Total Value: $18,253,798

Total Shares: 57,401,966

Institutional Ownership Trend

26 quarters

Holder Concentration

Across 61 13F filers · Δ vs Mar 31, 2026

Top Holder

26.7%

+6.6 pts

Top 5

79.9%

+5.9 pts

Top 10

91.7%

−1.9 pts

HHI

1,574

Moderately concentrated+280

Quarterly Activity

vs Mar 31, 2026

New

Increased

Decreased

Sold Out

Unchanged

Holder count: -3

Institutional value: -27.5%

Shares held: -24.7%

Top Buyers

vs Mar 31, 2026

Institution	Added	Now Holds
Mega TWO SIGMA INVESTMENTS, LP	+1,131,402	1,319,241
Mega CITADEL ADVISORS LLC	+545,258	1,000,058
Mega JANE STREET GROUP, LLC	+452,971	786,744
Mid XTX Topco Ltd	+90,012	174,481
Mega JPMORGAN CHASE & CO	+36,683	58,531

Top Sellers

vs Mar 31, 2026

Institution	Sold	Now Holds
Mid EcoR1 Capital, LLC	−12,368,855	1,000,000
Small Newtyn Management, LLC	−4,079,056	3,000,000
Large MARSHALL WACE, LLP	−507,103	179,884
Mega BlackRock, Inc.	−233,313	69,678
Mid 683 Capital Management, LLC	−222,144	11,777,856

Top New Positions

vs Mar 31, 2026

Institution	Acquired	Value (USD)
Small Ishara Investments LP	768,750	$244,462
Large NOMURA HOLDINGS INC	104,361	$33,186
Small James J. Burns & Company, LLC	95,400	$30,337
Mid Quarry LP	93,750	$29,812
Mega GOLDMAN SACHS GROUP INC	85,180	$27,087

Top Sold-Out Positions

vs Mar 31, 2026

Institution	Previously Held	Last Value (USD)
Mega MILLENNIUM MANAGEMENT LLC	3,559,103	$1,174,503
Small Knott David M Jr	300,337	$99,111
Large ACADIAN ASSET MANAGEMENT LLC	209,084	$68,997
Mid ADAR1 Capital Management, LLC	150,000	$49,500
Micro Forefront Analytics, LLC	127,778	$42,166

Filter: New 14 Increased 13 Reduced 13 Sold out 17 Unchanged 21

Showing 66 of 66

All Common Calls Puts

Compact Export CSV

Holder

Value (USD)

% of 13F

Rubric Capital Management LP

$4,867,736

26.67%

15,307,347

683 Capital Management, LLC

$3,745,358

20.52%

11,777,856

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
683 Capital Partners, LP	11,777,856	$3,745,358	100.0%	Defined

BANK OF AMERICA CORP /DE/

$2,606,099

14.28%

8,195,281

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
BOFA SECURITIES, INC.	8,195,281	$2,606,099	100.0%	Defined

Defilade Capital Management, L.P.

$2,403,684

13.17%

7,558,756

Newtyn Management, LLC

$954,000

5.23%

3,000,000

Tejara Capital Ltd

$647,931

3.55%

2,037,520

UBS Group AG

$460,344

2.52%

1,447,627

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
UBS Financial Services Inc	5,912	$1,880	0.4%	Defined
UBS AG	1,344,248	$427,470	92.9%	Defined
UBS Securities LLC	97,467	$30,994	6.7%	Defined

TWO SIGMA INVESTMENTS, LP

$419,518

2.30%

1,319,241

EcoR1 Capital, LLC

$318,000

1.74%

1,000,000

JANE STREET GROUP, LLC

$246,431

1.35%

774,944

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Jane Street Capital, LLC	486,971	$154,856	62.8%	Defined
Jane Street Global Trading, LLC	287,973	$91,575	37.2%	Defined

Ishara Investments LP

$244,462

1.34%

768,750

Wealthspire Advisors, LLC

$243,270

1.33%

765,000

CITADEL ADVISORS LLC

$160,558

0.88%

504,900

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Citadel Securities GP LLC	504,900	$160,558	100.0%	Defined

CITADEL ADVISORS LLC

$141,242

0.77%

444,158

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Citadel Securities GP LLC	430,780	$136,988	97.0%	Defined
Held directly	13,378	$4,254	3.0%	Defined

Rangeley Capital, LLC

$104,685

0.57%

329,200

SUSQUEHANNA INTERNATIONAL GROUP, LLP

$67,819

0.37%

213,270

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
SUSQUEHANNA SECURITIES, LLC	213,270	$67,819	100.0%	Other

MARSHALL WACE, LLP

$57,202

0.31%

179,884

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Marshall Wace North America L.P. joint	179,884	$57,202	100.0%	Other

XTX Topco Ltd

$55,484

0.30%

174,481

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
XTX EXECUTION SERVICES LLC joint	174,481	$55,484	100.0%	Defined

SUSQUEHANNA INTERNATIONAL GROUP, LLP

$55,173

0.30%

173,500

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
SUSQUEHANNA SECURITIES, LLC	173,500	$55,173	100.0%	Other

GROUP ONE TRADING LLC

$53,269

0.29%

167,515

STATE STREET CORP

$42,857

0.23%

134,772

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
SSGA FUNDS MANAGEMENT, INC.	134,772	$42,857	100.0%	Defined

NOMURA HOLDINGS INC

$33,186

0.18%

104,361

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
NOMURA SECURITIES INTERNATIONAL INC	104,361	$33,186	100.0%	Defined

James J. Burns & Company, LLC

$30,337

0.17%

95,400

Quarry LP

$29,812

0.16%

93,750

GOLDMAN SACHS GROUP INC

$27,087

0.15%

85,180

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
GOLDMAN SACHS & CO. LLC	85,180	$27,087	100.0%	Defined

JMN Financial LLC

$24,405

0.13%

76,748

BlackRock, Inc.

$22,157

0.12%

69,678

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Aperio Group, LLC	69,678	$22,157	100.0%	Sole

Virtu Financial LLC

$19,488

0.11%

61,285

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Virtu Americas LLC	61,285	$19,488	100.0%	Defined

JPMORGAN CHASE & CO

$18,612

0.10%

58,531

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
JPMorgan Chase Bank, N.A.	1,296	$412	2.2%	Defined
J.P. Morgan Securities LLC	56,923	$18,101	97.3%	Defined
J.P. Morgan Securities plc	312	$99	0.5%	Defined

RENAISSANCE TECHNOLOGIES LLC

$16,567

0.09%

52,100

CITADEL ADVISORS LLC

$16,218

0.09%

51,000

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Citadel Securities GP LLC	51,000	$16,218	100.0%	Defined

SUSQUEHANNA INTERNATIONAL GROUP, LLP

$14,628

0.08%

46,000

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
SUSQUEHANNA SECURITIES, LLC	46,000	$14,628	100.0%	Other

Significant Wealth Partners LLC

$10,391

0.06%

32,677

Clear Harbor Asset Management, LLC

$10,176

0.06%

32,000

RHUMBLINE ADVISERS

$8,517

0.05%

26,784

Centiva Capital, LP

$7,950

0.04%

25,000

Engineers Gate Manager LP

$7,617

0.04%

23,953

SIMPLEX TRADING, LLC

$5,972

0.03%

18,780

NFSG Corp

$5,962

0.03%

18,750

OneDigital Investment Advisors LLC

$5,819

0.03%

18,300

MORGAN STANLEY

$5,318

0.03%

16,731

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
MORGAN STANLEY & CO. LLC	172	$54	1.0%	Defined
MORGAN STANLEY CAPITAL SERVICES, LLC	14,006	$4,453	83.7%	Defined
MORGAN STANLEY SMITH BARNEY LLC	2,553	$811	15.3%	Defined

IHT Wealth Management, LLC

$4,770

0.03%

15,000

TWO SIGMA SECURITIES, LLC

$4,102

0.02%

12,900

J. Safra Sarasin Holding AG

$4,083

0.02%

12,841

SG Americas Securities, LLC

$4,071

0.02%

12,802

MML INVESTORS SERVICES, LLC

$3,879

0.02%

12,200

JANE STREET GROUP, LLC

$3,752

0.02%

11,800

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Jane Street Capital, LLC	11,800	$3,752	100.0%	Defined

World Investment Advisors

$3,180

0.02%

10,000

Astoria Portfolio Advisors LLC.

$3,180

0.02%

10,000

GAMMA Investing LLC

$2,959

0.02%

9,308

Arax Advisory Partners

$1,850

0.01%

5,819

Rockefeller Capital Management L.P.

$636

0.00%

2,000

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
ROCKEFELLER FINANCIAL LLC	2,000	$636	100.0%	Defined

Allworth Financial LP

$477

0.00%

1,500

OSAIC HOLDINGS, INC.

$477

0.00%

1,500

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
OSAIC WEALTH, INC.	1,000	$318	66.7%	Defined
Osaic Advisory Services, LLC	500	$159	33.3%	Defined

Markowski Investments

$477

0.00%

1,500

SIT INVESTMENT ASSOCIATES INC

$308

0.00%

970

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
SIT FIXED INCOME ADVISORS II LLC /ADV	970	$308	100.0%	Sole

New England Capital Financial Advisors LLC

$95

0.00%

300

WELLS FARGO & COMPANY/MN

$73

0.00%

231

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
WELLS FARGO ADVISORS FINANCIAL NETWORK, LLC	1	$0	0.0%	Defined
WELLS FARGO CLEARING SERVICES, LLC	230	$73	100.0%	Defined

SBI Securities Co., Ltd.

$36

0.00%

114

EverSource Wealth Advisors, LLC

$31

0.00%

100

CITIGROUP INC

$16

0.00%

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Citigroup Financial Products Inc. joint	52	$16	100.0%	Defined

US BANCORP \DE\

0.00%

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
US BANK NATIONAL ASSOCIATION	13	$4	100.0%	Defined

BNP PARIBAS ARBITRAGE, SA

0.00%

Axiom Investment Management LLC

0.00%

Integrated Wealth Concepts LLC

0.00%

Caitong International Asset Management Co., Ltd

0.00%

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Dorset Partners LLC	300,337	$99,111	100.0%	Defined

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
Acadian Inc	209,084	$68,997	100.0%	Defined

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
STONEX FINANCIAL INC.	36,873	$12,168	100.0%	Defined

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
BARCLAYS CAPITAL INC.	2,496	$823	100.0%	Defined

This filing is a combination report: the position is filed across the managers below.

Manager	Shares	Value (USD)	% of position	Discretion
National Bank Financial Inc.	46	$15	100.0%	Defined

Key facts CIK 1719714 CUSIP 589492107 13F (30d) 54 filings 53 filers Visit website Investor relations