Mereo Biopharma Group plc: which funds bought and sold

Institutions that bought and sold Mereo Biopharma Group shares in Q2 2026, from the holdings they reported to the SEC on Form 13F for March 31, 2026 and June 30, 2026.

Between March 31, 2026 and June 30, 2026, 24 institutions that filed 13F reports for both quarters added to or opened positions in Mereo Biopharma Group, and 29 cut or closed them. Together they sold a net 18.8M shares, −24.9% on what they held at the start of the quarter. Active managers and hedge funds on our list were net sellers of 15.4M shares (−33.9%); index fund managers were net sellers of 317K shares (−57.8%). 12 opened a new position and 17 sold out entirely.

Bought, Q2 2026 24 institutions, 12 of them new holders Sold, Q2 2026 29 institutions, 17 of them sold out

Net change, all compared −18.8M shares (−24.9%)

Net change, active managers −15.4M shares (−33.9%), 3 bought, 7 sold

Buyers versus sellers

institutions compared, 73

24 bought 20 29 sold

Active managers and hedge funds 3 bought · 7 sold · −15.4M

Index fund managers 2 bought · 2 sold · −317K

Other institutions 19 bought · 20 sold · −3.0M

Biggest buyers

by change in shares held

Biggest buyers
Institution	Change in shares	Shares June 30, 2026	Value
Two Sigma Investments, LP Hedge fund	+1.1M +602.3%	1.3M	$419,123
Ishara Investments LP	+769K New position	769K	$244,232
Jane Street Group, LLC	+635K +453.6%	775K	$246,200
Citadel Advisors LLC Hedge fund	+444K New position	444K	$141,109
Nomura Holdings Inc	+104K New position	104K	$33,155
James J. Burns & Company, LLC	+95K New position	95K	$30,309
Quarry LP	+94K New position	94K	$29,784
Xtx Topco Ltd	+90K +106.6%	174K	$55,433
Goldman Sachs Group Inc	+85K New position	85K	$27,062
Jmn Financial LLC	+77K New position	77K	$24,383
Jpmorgan Chase & Co	+37K +167.9%	59K	$19,421
Virtu Financial LLC	+25K +68.1%	61K	$19,000
Simplex Trading, LLC	+19K New position	19K	$5,972
Susquehanna International Group, LLP	+17K +8.9%	213K	$67,756
Two Sigma Securities, LLC	+13K New position	13K	$4,098
J. Safra Sarasin Holding AG	+13K New position	13K	$4,081
SG Americas Securities, LLC	+13K New position	13K	$4,000
Rhumbline Advisers Index funds	+7,212 +36.8%	27K	$8,511
Significant Wealth Partners LLC	+7,043 +27.5%	33K	$10,382
Renaissance Technologies LLC Hedge fund	+3,700 +7.6%	52K	$16,552

Biggest buyers, active managers and hedge funds
Institution	Change in shares	Shares June 30, 2026	Value
Two Sigma Investments, LP Hedge fund	+1.1M +602.3%	1.3M	$419,123
Citadel Advisors LLC Hedge fund	+444K New position	444K	$141,109
Renaissance Technologies LLC Hedge fund	+3,700 +7.6%	52K	$16,552

Biggest sellers

by change in shares held

Biggest sellers
Institution	Change in shares	Shares June 30, 2026	Value
Ecor1 Capital, LLC Hedge fund	−12.4M −92.5%	1.0M	$317,700
Newtyn Management, LLC	−4.1M −57.6%	3.0M	$953,100
Millennium Management LLC Hedge fund	−3.6M Sold out	0	—
Marshall Wace, LLP Hedge fund	−507K −73.8%	180K	$57,563
Knott David M Jr	−300K Sold out	0	—
Blackrock, Inc. Index funds	−233K −77.0%	70K	$22,137
683 Capital Management, LLC Hedge fund	−222K −1.9%	11.8M	$3.7M
Acadian Asset Management LLC Active manager	−209K Sold out	0	—
Group One Trading LLC	−168K −50.1%	168K	$53,220
ADAR1 Capital Management, LLC Hedge fund	−150K Sold out	0	—
Forefront Analytics, LLC	−128K Sold out	0	—
Virtus Investment Advisers, LLC	−126K Sold out	0	—
Geode Capital Management, LLC Index funds	−93K Sold out	0	—
Caption Management, LLC	−64K Sold out	0	—
Smartharvest Portfolios, LLC	−50K Sold out	0	—
UBS Group AG	−43K −2.9%	1.4M	$460,346
Stonex Group Inc.	−37K Sold out	0	—
Independent Advisor Alliance	−35K Sold out	0	—
Wealthspire Advisors, LLC	−31K −3.9%	765K	$243,041
Three Magnolias Financial Advisors, LLC	−19K Sold out	0	—

Biggest sellers, active managers and hedge funds
Institution	Change in shares	Shares June 30, 2026	Value
Ecor1 Capital, LLC Hedge fund	−12.4M −92.5%	1.0M	$317,700
Millennium Management LLC Hedge fund	−3.6M Sold out	0	—
Marshall Wace, LLP Hedge fund	−507K −73.8%	180K	$57,563
683 Capital Management, LLC Hedge fund	−222K −1.9%	11.8M	$3.7M
Acadian Asset Management LLC Active manager	−209K Sold out	0	—
ADAR1 Capital Management, LLC Hedge fund	−150K Sold out	0	—
Engineers Gate Manager LP Hedge fund	−1 0.0%	24K	$7,610

New positions

largest by value

Institution	Shares	Value June 30, 2026
Ishara Investments LP	769K	$244,232
Citadel Advisors LLCHedge fund	444K	$141,109
Nomura Holdings Inc	104K	$33,155
James J. Burns & Company, LLC	95K	$30,309
Quarry LP	94K	$29,784
Goldman Sachs Group Inc	85K	$27,062
Jmn Financial LLC	77K	$24,383
Simplex Trading, LLC	19K	$5,972
Two Sigma Securities, LLC	13K	$4,098
J. Safra Sarasin Holding AG	13K	$4,081

Sold out

largest by value

Institution	Shares	Value March 31, 2026
Millennium Management LLCHedge fund	3.6M	$1.2M
Knott David M Jr	300K	$99,111
Acadian Asset Management LLCActive manager	209K	$68,000
ADAR1 Capital Management, LLCHedge fund	150K	$49,500
Forefront Analytics, LLC	128K	$42,167
Virtus Investment Advisers, LLC	126K	$41,468
Geode Capital Management, LLCIndex funds	93K	$30,536
Caption Management, LLC	64K	$21,141
Smartharvest Portfolios, LLC	50K	$16,339
Stonex Group Inc.	37K	$12,168

Who holds the shares

13F holdings at June 30, 2026

Institutions reporting: 57
Ten largest holders: 92.6%
Index fund managers: 0.4%
Active managers and hedge funds: 53.2%

Buying and selling by type of institution, March 31, 2026 to June 30, 2026
Type	Bought	Sold	New	Sold out	Net change in shares	Net %
Active managers and hedge funds	3	7	1	3	−15.4M	−33.9%
Index fund managers	2	2	0	1	−317K	−57.8%
Other institutions	19	20	11	13	−3.0M	−10.3%

Active managers and hedge funds: a list we maintain of about 400 well-known stock-picking firms and hedge funds, matched by SEC registration number (CIK) and checked against the filer names each quarter. Index fund managers: the large index houses, such as BlackRock, Vanguard, State Street, Geode and Northern Trust. Every other filer (banks, brokers, wealth managers, pension funds, insurers and firms not on the list) counts as another institution. A firm that files under several SEC registrations appears once for each.

What these filings can and cannot tell you

Form 13F lists the long positions in US-listed shares held by investment managers with more than $100 million in such holdings. Managers file it up to 45 days after each quarter ends, so this page shows what funds held at the end of each quarter, not what they are doing now: a position may have changed since. Short positions, most derivatives and smaller managers are not included, and a cut can mean a fund lost clients or rebalanced rather than a view on Mereo Biopharma Group.

Only managers that filed a holdings report for both quarters are compared (73 here). 1 other holder is left out: first-time or late filers, firms that changed their SEC registration, and filings that withheld positions under confidential treatment, any of which would otherwise look like a new position or a sale. Figures are as reported by each manager in the SEC's quarterly 13F data sets; option positions are excluded.

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