MCRB · Seres Therapeutics, Inc. · Shareholders & Ownership

$2.10 -0.03 (-1.41%)

Market Cap

$21.17M

9.94M

Volume · Oct 22 132.21K Avg daily vol (3M) 65.57K

Every disclosed holder of MCRB 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.

How the holder list picks a filing →

Who Owns MCRB

13F quarter Sep 30, 2026, combined view: filers that have not filed yet carry their Jun 30, 2026 positions

Holder group	Holders	Shares	% Out	Summed
Institutional (13F)	35	2,261,388	22.75%	Yes
Insiders (Forms 3, 4, 5)	6	47,841	0.48%	Yes
13D/G-only blocks	3	1,347,902	13.56%	Yes
Remaining	—	6,284,130	63.21%	Rest
Registered funds (N-PORT, not summed)	23	493,475	4.96%	No

Shares outstanding: 9,941,261, 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 MCRB

One row per holder Every filing By ultimate parent

All 13F Funds Insiders 13D/G Non-US

#	Holder	Shares	% Out	Change	As of	Notes
1	Flagship Pioneering, LLC 13F CIK 1400240 · Exempt reporting adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	1,155,850	11.63%	0	Jun 30, 2026	carried, not yet filed for the newest quarter
2	Nestlé S.A. 13D CIK 792990 · Unknown · Sep 30, 2024	1,089,088	10.96%	—	Sep 30, 2024
3	VANGUARD CAPITAL MANAGEMENT LLC 13F CIK 2100119 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	287,776	2.89%	-6,367	Jun 30, 2026	carried, not yet filed for the newest quarter
4	FEDERATED HERMES, INC. 13G CIK 1056288 · Investment adviser · Oct 31, 2023	258,790	2.60%	—	Oct 31, 2023
5	VANGUARD TOTAL STOCK MARKET INDEX FUND Fund S000002848 · Registered fund · Jun 30, 2026 VANGUARD INDEX FUNDS, not summed	206,170	2.07%	0	Jun 30, 2026	VANGUARD INDEX FUNDS, not summed
6	MARSHALL WACE, LLP 13F CIK 1318757 · Exempt reporting adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	172,245	1.73%	+32,706	Jun 30, 2026	carried, not yet filed for the newest quarter
7	Vontobel Holding Ltd. 13F CIK 1588340 · Unknown · Sep 30, 2026	114,566	1.15%	-8,409	Sep 30, 2026
8	BlackRock, Inc. 13F CIK 2012383 · Holding company · Jun 30, 2026 carried, not yet filed for the newest quarter	111,000	1.12%	+8,974	Jun 30, 2026	carried, not yet filed for the newest quarter
8.1	iShares Micro-Cap ETF Fund S000004439 · Registered fund · Jun 30, 2026 iShares Trust, not summed	25,389	0.26%	+8,640	Jun 30, 2026	iShares Trust, not summed
9	GEODE CAPITAL MANAGEMENT, LLC 13F CIK 1214717 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	79,974	0.80%	+5,139	Jun 30, 2026	carried, not yet filed for the newest quarter
10	VANGUARD EXTENDED MARKET INDEX FUND Fund S000002841 · Registered fund · Jun 30, 2026 VANGUARD INDEX FUNDS, not summed	75,849	0.76%	+5,903	Jun 30, 2026	VANGUARD INDEX FUNDS, not summed
11	SUSQUEHANNA INTERNATIONAL GROUP, LLP 13F CIK 1446194 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	58,328	0.59%	-47,011	Jun 30, 2026	carried, not yet filed for the newest quarter
12	VANGUARD FIDUCIARY TRUST CO 13F CIK 933478 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	48,685	0.49%	+9,042	Jun 30, 2026	carried, not yet filed for the newest quarter
13	Avantis U.S. Small Cap Value ETF Fund S000066459 · Registered fund · May 31, 2026 American Century ETF Trust, not summed	37,364	0.38%	-18,669	May 31, 2026	American Century ETF Trust, not summed
14	STATE STREET CORP 13F CIK 93751 · Bank · Jun 30, 2026 carried, not yet filed for the newest quarter	33,901	0.34%	0	Jun 30, 2026	carried, not yet filed for the newest quarter
15	Lion Point Capital, LP 13F CIK 1643354 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	31,570	0.32%	0	Jun 30, 2026	carried, not yet filed for the newest quarter
16	CHARLES SCHWAB INVESTMENT MANAGEMENT INC 13F CIK 884546 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	31,049	0.31%	-581	Jun 30, 2026	carried, not yet filed for the newest quarter
16.1	Schwab U.S. Small-Cap ETF Fund S000026636 · Registered fund · May 31, 2026 SCHWAB STRATEGIC TRUST, not summed	31,077	0.31%	-436	May 31, 2026	SCHWAB STRATEGIC TRUST, not summed
17	AMERICAN CENTURY COMPANIES INC 13F CIK 748054 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	28,313	0.28%	-34,003	Jun 30, 2026	carried, not yet filed for the newest quarter
18	XTX Topco Ltd 13F CIK 1828301 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	20,732	0.21%	+20,732	Jun 30, 2026	carried, not yet filed for the newest quarter
19	GOLDMAN SACHS GROUP INC 13F CIK 886982 · Holding company · Jun 30, 2026 carried, not yet filed for the newest quarter	15,229	0.15%	+15,229	Jun 30, 2026	carried, not yet filed for the newest quarter
19.1	Goldman Sachs Absolute Return Tracker Fund Fund S000020314 · Registered fund · Jun 30, 2026 GOLDMAN SACHS TRUST, not summed	10,065	0.10%	+7,397	Jun 30, 2026	GOLDMAN SACHS TRUST, not summed
20	NORTHERN TRUST CORP 13F CIK 73124 · Bank · Jun 30, 2026 carried, not yet filed for the newest quarter	14,765	0.15%	0	Jun 30, 2026	carried, not yet filed for the newest quarter
21	Invesco Ltd. 13F CIK 914208 · Investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	12,974	0.13%	-1,573	Jun 30, 2026	carried, not yet filed for the newest quarter
21.1	Invesco RAFI US 1500 Small-Mid ETF Fund S000013120 · Registered fund · Jul 31, 2026 Invesco Exchange-Traded Fund Trust, not summed	12,914	0.13%	-1,624	Jul 31, 2026	Invesco Exchange-Traded Fund Trust, not summed
22	Shaff Eric D. Insider CIK 1643734 · Aug 17, 2026 Director, issuer-wide	12,499	0.13%	+459	Aug 17, 2026	Director, issuer-wide
23	MORGAN STANLEY 13F CIK 895421 · Holding company · Jun 30, 2026 carried, not yet filed for the newest quarter	12,138	0.12%	-9,562	Jun 30, 2026	carried, not yet filed for the newest quarter
24	CITADEL ADVISORS LLC 13F CIK 1423053 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	10,504	0.11%	+10,504	Jun 30, 2026	carried, not yet filed for the newest quarter
25	Brady Kelly Insider CIK 2117686 · Aug 17, 2026 See Remarks, issuer-wide	8,679	0.09%	+117	Aug 17, 2026	See Remarks, issuer-wide
26	Young Teresa L. Insider CIK 1814656 · Feb 15, 2026 See Remarks, issuer-wide	8,557	0.09%	+156	Feb 15, 2026	See Remarks, issuer-wide
27	DesRosier Thomas Insider CIK 1435744 · Aug 17, 2026 See Remarks, issuer-wide	8,117	0.08%	+163	Aug 17, 2026	See Remarks, issuer-wide
28	Henn Matthew R Insider CIK 1767321 · Aug 17, 2026 See Remarks, issuer-wide	7,995	0.08%	+157	Aug 17, 2026	See Remarks, issuer-wide
29	U.S. MICRO CAP PORTFOLIO Fund S000000948 · Registered fund · Jul 31, 2026 DFA INVESTMENT DIMENSIONS GROUP INC, not summed	7,662	0.08%	0	Jul 31, 2026	DFA INVESTMENT DIMENSIONS GROUP INC, not summed
30	Ultra-Small Company Market Fund Fund S000004424 · Registered fund · Jun 30, 2026 Bridgeway Funds, Inc., not summed	7,500	0.08%	0	Jun 30, 2026	Bridgeway Funds, Inc., not summed
31	WisdomTree U.S. SmallCap Fund Fund S000015507 · Registered fund · Jun 30, 2026 WisdomTree Trust, not summed	7,058	0.07%	-165	Jun 30, 2026	WisdomTree Trust, not summed
32	Avantis U.S. Small Cap Equity ETF Fund S000074835 · Registered fund · May 31, 2026 American Century ETF Trust, not summed	5,277	0.05%	-158	May 31, 2026	American Century ETF Trust, not summed
33	SIMPLEX TRADING, LLC 13F CIK 1488542 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	4,598	0.05%	+1,528	Jun 30, 2026	carried, not yet filed for the newest quarter
34	VANGUARD BALANCED INDEX FUND Fund S000002560 · Registered fund · Jun 30, 2026 VANGUARD VALLEY FORGE FUNDS, not summed	4,386	0.04%	+888	Jun 30, 2026	VANGUARD VALLEY FORGE FUNDS, not summed
35	GROUP ONE TRADING LLC 13F CIK 932540 · Broker-dealer · Jun 30, 2026 carried, not yet filed for the newest quarter	3,714	0.04%	+2,890	Jun 30, 2026	carried, not yet filed for the newest quarter
36	JPMORGAN CHASE & CO 13F CIK 19617 · Bank · Jun 30, 2026 carried, not yet filed for the newest quarter	3,636	0.04%	+3,636	Jun 30, 2026	carried, not yet filed for the newest quarter
37	SBI Securities Co., Ltd. 13F CIK 1851815 · Non-US institution · Sep 30, 2026	3,601	0.04%	-581	Sep 30, 2026
38	von Moltke Lisa Insider CIK 1808592 · Feb 18, 2025 See Remarks, issuer-wide	1,994	0.02%	+373	Feb 18, 2025	See Remarks, issuer-wide
39	Vanguard Global Advisers, LLC 13F CIK 1811242 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	1,975	0.02%	0	Jun 30, 2026	carried, not yet filed for the newest quarter
40	1290 VT Micro Cap Portfolio Fund S000044688 · Registered fund · Jun 30, 2026 EQ Advisors Trust, not summed	1,689	0.02%	+374	Jun 30, 2026	EQ Advisors Trust, not summed
41	FMR LLC 13F CIK 315066 · Holding company · Jun 30, 2026 carried, not yet filed for the newest quarter	1,528	0.02%	-224	Jun 30, 2026	carried, not yet filed for the newest quarter
41.1	Fidelity Extended Market Index Fund Fund S000006021 · Registered fund · May 31, 2026 Fidelity Concord Street Trust, not summed	26,335	0.26%	+2,155	May 31, 2026	Fidelity Concord Street Trust, not summed
41.2	Fidelity Total Market Index Fund Fund S000006026 · Registered fund · May 31, 2026 Fidelity Concord Street Trust, not summed	13,870	0.14%	0	May 31, 2026	Fidelity Concord Street Trust, not summed
41.3	Fidelity Series Total Market Index Fund Fund S000065248 · Registered fund · May 31, 2026 Fidelity Concord Street Trust, not summed	10,143	0.10%	0	May 31, 2026	Fidelity Concord Street Trust, not summed
41.4	Fidelity Nasdaq Composite Index Fund Fund S000055366 · Registered fund · May 31, 2026 Fidelity Concord Street Trust, not summed	5,666	0.06%	+1,178	May 31, 2026	Fidelity Concord Street Trust, not summed
42	Rachor Investment Advisory Services, LLC 13F CIK 2008792 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	1,477	0.01%	0	Jun 30, 2026	carried, not yet filed for the newest quarter
43	Large-Cap Growth Portfolio Fund S000026003 · Registered fund · Jun 30, 2026 PACIFIC SELECT FUND, not summed	1,430	0.01%	0	Jun 30, 2026	PACIFIC SELECT FUND, not summed
44	VANGUARD INSTITUTIONAL TOTAL STOCK MARKET INDEX FUND Fund S000002855 · Registered fund · Jun 30, 2026 VANGUARD INSTITUTIONAL INDEX FUNDS, not summed	1,371	0.01%	-13,158	Jun 30, 2026	VANGUARD INSTITUTIONAL INDEX FUNDS, not summed
45	Avantis U.S. Small Cap Value Fund Fund S000066461 · Registered fund · May 31, 2026 American Century ETF Trust, not summed	1,176	0.01%	0	May 31, 2026	American Century ETF Trust, not summed
46	Avantis U.S. Equity ETF Fund S000066458 · Registered fund · May 31, 2026 American Century ETF Trust, not summed	1,022	0.01%	0	May 31, 2026	American Century ETF Trust, not summed
47	UBS Group AG 13F CIK 1610520 · Bank · Jun 30, 2026 carried, not yet filed for the newest quarter	484	0.00%	-6,546	Jun 30, 2026	carried, not yet filed for the newest quarter
48	Tower Research Capital LLC (TRC) 13F CIK 1533421 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	316	0.00%	-478	Jun 30, 2026	carried, not yet filed for the newest quarter
49	BNP PARIBAS ARBITRAGE, SA 13F CIK 1166588 · Non-US institution · Jun 30, 2026 carried, not yet filed for the newest quarter	211	0.00%	0	Jun 30, 2026	carried, not yet filed for the newest quarter
50	BARCLAYS PLC 13F CIK 312069 · Bank · Jun 30, 2026 carried, not yet filed for the newest quarter	167	0.00%	-6,340	Jun 30, 2026	carried, not yet filed for the newest quarter

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.

Showing 1–50 of 59 holders

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Key facts CIK 1609809 CUSIP 81750R201 13F (30d) 2 filings 2 filers Visit website Investor relations