MCRB · Seres Therapeutics, Inc.

$5.11 +0.16 (+3.23%) At close · Aug 28

Market Cap

$49.21M

9.94M

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: 36

Total Value: $18,878,993

Total Shares: 2,392,778

Institutional Ownership Trend

26 quarters

Holder Concentration

Across 36 13F filers · Δ vs Mar 31, 2026

Top Holder

48.3%

+1.8 pts

Top 5

78.2%

−0.3 pts

Top 10

91.9%

−0.3 pts

HHI

2,638

Highly concentrated+146

Quarterly Activity

vs Mar 31, 2026

New

Increased

Decreased

Sold Out

Unchanged

Holder count: +2

Institutional value: -14.4%

Shares held: -3.8%

Top Buyers

vs Mar 31, 2026

Institution	Added	Now Holds
Large MARSHALL WACE, LLP	+32,706	172,245
Mega VANGUARD FIDUCIARY TRUST CO	+9,042	48,685
Mega BlackRock, Inc.	+8,974	111,000
Mega GEODE CAPITAL MANAGEMENT, LLC	+5,139	79,974
Mid GROUP ONE TRADING LLC	+2,890	3,714

Top Sellers

vs Mar 31, 2026

Institution	Sold	Now Holds
Mega SUSQUEHANNA INTERNATIONAL GROUP, LLP	−93,711	133,228
Mega AMERICAN CENTURY COMPANIES INC	−34,003	28,313
Large Vontobel Holding Ltd.	−15,493	122,975
Mega MORGAN STANLEY	−9,562	12,138
Mega UBS Group AG	−6,546	484

Top New Positions

vs Mar 31, 2026

Institution	Acquired	Value (USD)
Mid XTX Topco Ltd	20,732	$163,575
Mega GOLDMAN SACHS GROUP INC	15,229	$120,156
Mid Integrated Wealth Concepts LLC	4,000	$31,560
Mega JPMORGAN CHASE & CO	3,636	$28,687
Small Continuum Advisory, LLC	47	$370

Top Sold-Out Positions

vs Mar 31, 2026

Institution	Previously Held	Last Value (USD)
Mega TWO SIGMA INVESTMENTS, LP	18,794	$166,702
Small Physician Wealth Advisors, Inc.	142	$1,259
Mid Sound Income Strategies, LLC	8	$70
Mid Arax Advisory Partners	6	$53
Mid Allworth Financial LP	4	$35

Filter: New 7 Increased 7 Reduced 13 Sold out 5 Unchanged 9

Showing 39 of 39

All Common Calls Puts

Compact Export CSV

Holder

Value (USD)

% of 13F

Flagship Pioneering, LLC

$9,119,656

48.31%

1,155,850

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

Manager	Shares	Value (USD)	% of position	Discretion
Flagship Ventures Fund IV General Partner LLC joint	422,643	$3,334,653	36.6%	Defined
Noubar Afeyan	733,207	$5,785,003	63.4%	Defined

VANGUARD CAPITAL MANAGEMENT LLC

$2,270,552

12.03%

287,776

MARSHALL WACE, LLP

$1,359,012

7.20%

172,245

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	172,245	$1,359,012	100.0%	Other

Vontobel Holding Ltd.

$970,272

5.14%

122,975

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

Manager	Shares	Value (USD)	% of position	Discretion
BANK VONTOBEL AG	122,975	$970,272	100.0%	Defined

BlackRock, Inc.

$875,789

4.64%

111,000

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

Manager	Shares	Value (USD)	% of position	Discretion
BlackRock Investment Management, LLC	1,698	$13,397	1.5%	Sole
BlackRock Fund Advisors	25,389	$200,319	22.9%	Sole
BlackRock Institutional Trust Company, N.A.	83,913	$662,073	75.6%	Sole

GEODE CAPITAL MANAGEMENT, LLC

$630,994

3.34%

79,974

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

Manager	Shares	Value (USD)	% of position	Discretion
GEODE CAPITAL MANAGEMENT TRUST COMPANY, LLC	15,004	$118,381	18.8%	Defined
Held directly	64,970	$512,613	81.2%	Defined

SUSQUEHANNA INTERNATIONAL GROUP, LLP

$503,382

2.67%

63,800

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

Manager	Shares	Value (USD)	% of position	Discretion
SUSQUEHANNA SECURITIES, LLC	63,800	$503,382	100.0%	Other

SUSQUEHANNA INTERNATIONAL GROUP, LLP

$460,207

2.44%

58,328

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

Manager	Shares	Value (USD)	% of position	Discretion
SUSQUEHANNA SECURITIES, LLC	58,328	$460,207	100.0%	Other

VANGUARD FIDUCIARY TRUST CO

$384,124

2.03%

48,685

CITADEL ADVISORS LLC

$343,215

1.82%

43,500

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	43,500	$343,215	100.0%	Defined

STATE STREET CORP

$267,478

1.42%

33,901

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

Manager	Shares	Value (USD)	% of position	Discretion
STATE STREET GLOBAL ADVISORS TRUST COMPANY	33,901	$267,478	100.0%	Defined

Lion Point Capital, LP

$249,087

1.32%

31,570

CHARLES SCHWAB INVESTMENT MANAGEMENT INC

$244,976

1.30%

31,049

AMERICAN CENTURY COMPANIES INC

$223,389

1.18%

28,313

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

Manager	Shares	Value (USD)	% of position	Discretion
AMERICAN CENTURY INVESTMENT MANAGEMENT INC	28,313	$223,389	100.0%	Defined

XTX Topco Ltd

$163,575

0.87%

20,732

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	20,732	$163,575	100.0%	Defined

GOLDMAN SACHS GROUP INC

$120,156

0.64%

15,229

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

Manager	Shares	Value (USD)	% of position	Discretion
GOLDMAN SACHS ASSET MANAGEMENT, L.P.	15,229	$120,156	100.0%	Defined

NORTHERN TRUST CORP

$116,495

0.62%

14,765

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

Manager	Shares	Value (USD)	% of position	Discretion
NORTHERN TRUST CO joint	14,765	$116,495	100.0%	Defined

Invesco Ltd.

$102,364

0.54%

12,974

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

Manager	Shares	Value (USD)	% of position	Discretion
Invesco Capital Management LLC	12,974	$102,364	100.0%	Defined

MORGAN STANLEY

$95,767

0.51%

12,138

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	106	$836	0.9%	Defined
MORGAN STANLEY CAPITAL SERVICES, LLC	121	$954	1.0%	Defined
MORGAN STANLEY SMITH BARNEY LLC	11,911	$93,977	98.1%	Defined

SUSQUEHANNA INTERNATIONAL GROUP, LLP

$87,579

0.46%

11,100

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

Manager	Shares	Value (USD)	% of position	Discretion
SUSQUEHANNA SECURITIES, LLC	11,100	$87,579	100.0%	Other

CITADEL ADVISORS LLC

$82,876

0.44%

10,504

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	10,504	$82,876	100.0%	Defined

SIMPLEX TRADING, LLC

$36,278

0.19%

4,598

SBI Securities Co., Ltd.

$32,995

0.17%

4,182

Integrated Wealth Concepts LLC

$31,560

0.17%

4,000

GROUP ONE TRADING LLC

$29,303

0.16%

3,714

JPMORGAN CHASE & CO

$28,687

0.15%

3,636

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.	320	$2,524	8.8%	Defined
J.P. Morgan Securities LLC	3,316	$26,163	91.2%	Defined

Vanguard Global Advisers, LLC

$15,582

0.08%

1,975

FMR LLC

$12,055

0.06%

1,528

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

Manager	Shares	Value (USD)	% of position	Discretion
Fidelity Management & Research Co LLC	98	$773	6.4%	Defined
FIAM LLC	1,430	$11,282	93.6%	Defined

Rachor Investment Advisory Services, LLC

$11,653

0.06%

1,477

UBS Group AG

$3,818

0.02%

484

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	333	$2,627	68.8%	Defined
UBS AG	108	$852	22.3%	Defined
UBS Switzerland AG	35	$276	7.2%	Defined
UBS Securities LLC	8	$63	1.7%	Defined

Tower Research Capital LLC (TRC)

$2,493

0.01%

316

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

Manager	Shares	Value (USD)	% of position	Discretion
Latour Trading LLC (Latour)	316	$2,493	100.0%	Defined

BNP PARIBAS ARBITRAGE, SA

$1,664

0.01%

211

BARCLAYS PLC

$1,317

0.01%

167

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

Manager	Shares	Value (USD)	% of position	Discretion
BARCLAYS CAPITAL INC.	167	$1,317	100.0%	Defined

Continuum Advisory, LLC

$370

0.00%

ROYAL BANK OF CANADA

$86

0.00%

WELLS FARGO & COMPANY/MN

$78

0.00%

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

Manager	Shares	Value (USD)	% of position	Discretion
WELLS FARGO CLEARING SERVICES, LLC	10	$78	100.0%	Defined

OSAIC HOLDINGS, INC.

$63

0.00%

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

Manager	Shares	Value (USD)	% of position	Discretion
OSAIC WEALTH, INC.	8	$63	100.0%	Defined

Larson Financial Group LLC

$39

0.00%

WHITTIER TRUST CO OF NEVADA INC

0.00%

Key facts CIK 1609809 CUSIP 81750R201 13F (30d) 33 filings 33 filers Visit website Investor relations