SPRO · Spero Therapeutics, Inc. · Shareholders & Ownership

$1.11 -0.02 (-1.77%) At close · Oct 23

Market Cap

$64.64M

58.23M

Volume · Oct 23 316.55K Avg daily vol (3M) 825.88K

Every disclosed holder of SPRO 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 SPRO

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)	58	21,396,041	36.74%	Yes
Insiders (Forms 3, 4, 5)	12	4,943,299	8.49%	Yes
13D/G-only blocks	1	1,615,469	2.77%	Yes
Remaining	—	30,280,018	52.00%	Rest
Registered funds (N-PORT, not summed)	30	3,130,162	5.38%	No

Shares outstanding: 58,234,827, 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 SPRO

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	GSK plc 13F CIK 1131399 · Holding company · Jun 30, 2026 carried, not yet filed for the newest quarter	9,190,606	15.78%	0	Jun 30, 2026	carried, not yet filed for the newest quarter
2	Pfizer Inc 13F CIK 78003 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	2,362,348	4.06%	0	Jun 30, 2026	carried, not yet filed for the newest quarter
3	VANGUARD CAPITAL MANAGEMENT LLC 13F CIK 2100119 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	2,036,226	3.50%	+236,346	Jun 30, 2026	carried, not yet filed for the newest quarter
4	Shukla Sath Insider CIK 1782817 · Feb 5, 2025 EVP, Chief Financial Officer, issuer-wide	1,736,883	2.98%	+596,074	Feb 5, 2025	EVP, Chief Financial Officer, issuer-wide
5	Anson Funds Management LP 13G CIK 1491072 · Registered investment adviser · Jun 30, 2025 Rule 13d-1(b), qualified institution	1,615,469	2.77%	-2,134,981	Jun 30, 2025	Rule 13d-1(b), qualified institution
6	VANGUARD TOTAL STOCK MARKET INDEX FUND Fund S000002848 · Registered fund · Jun 30, 2026 VANGUARD INDEX FUNDS, not summed	1,395,976	2.40%	+159,200	Jun 30, 2026	VANGUARD INDEX FUNDS, not summed
7	Rajavelu Esther Insider CIK 1903716 · May 4, 2026 See Remarks, issuer-wide	986,851	1.69%	-25,240	May 4, 2026	See Remarks, issuer-wide
8	RENAISSANCE TECHNOLOGIES LLC 13F CIK 1037389 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	947,904	1.63%	-241,331	Jun 30, 2026	carried, not yet filed for the newest quarter
9	Alphabet Inc. 13F CIK 1652044 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	889,979	1.53%	0	Jun 30, 2026	carried, not yet filed for the newest quarter
10	SUSQUEHANNA INTERNATIONAL GROUP, LLP 13F CIK 1446194 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	759,290	1.30%	+426,175	Jun 30, 2026	carried, not yet filed for the newest quarter
11	Keutzer Timothy Insider CIK 1798155 · Feb 6, 2026 Chief Operating Officer, issuer-wide	742,506	1.28%	-18,652	Feb 6, 2026	Chief Operating Officer, issuer-wide
12	Mahadevia Ankit Insider CIK 1720974 · Aug 28, 2025 Director, issuer-wide	703,294	1.21%	-6,572	Aug 28, 2025	Director, issuer-wide
13	BlackRock, Inc. 13F CIK 2012383 · Holding company · Jun 30, 2026 carried, not yet filed for the newest quarter	594,404	1.02%	+161,202	Jun 30, 2026	carried, not yet filed for the newest quarter
13.1	iShares Micro-Cap ETF Fund S000004439 · Registered fund · Jun 30, 2026 iShares Trust, not summed	151,203	0.26%	—	Jun 30, 2026	iShares Trust, not summed
14	VANGUARD EXTENDED MARKET INDEX FUND Fund S000002841 · Registered fund · Jun 30, 2026 VANGUARD INDEX FUNDS, not summed	593,254	1.02%	+77,146	Jun 30, 2026	VANGUARD INDEX FUNDS, not summed
15	GEODE CAPITAL MANAGEMENT, LLC 13F CIK 1214717 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	566,329	0.97%	+46,407	Jun 30, 2026	carried, not yet filed for the newest quarter
16	RAYMOND JAMES FINANCIAL INC 13F CIK 720005 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	521,705	0.90%	+521,705	Jun 30, 2026	carried, not yet filed for the newest quarter
17	TWO SIGMA INVESTMENTS, LP 13F CIK 1179392 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	382,814	0.66%	-502,817	Jun 30, 2026	carried, not yet filed for the newest quarter
18	ARROWSTREET CAPITAL, LIMITED PARTNERSHIP 13F CIK 1164508 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	332,970	0.57%	+332,970	Jun 30, 2026	carried, not yet filed for the newest quarter
19	VANGUARD FIDUCIARY TRUST CO 13F CIK 933478 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	287,648	0.49%	+23,533	Jun 30, 2026	carried, not yet filed for the newest quarter
20	GSA CAPITAL PARTNERS LLP 13F CIK 1362033 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	285,906	0.49%	+7,602	Jun 30, 2026	carried, not yet filed for the newest quarter
21	DIMENSIONAL FUND ADVISORS LP 13F CIK 354204 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	274,820	0.47%	+245,052	Jun 30, 2026	carried, not yet filed for the newest quarter
21.1	Dimensional U.S. Small Cap ETF Fund S000070906 · Registered fund · Jul 31, 2026 Dimensional ETF Trust, not summed	65,997	0.11%	+50,063	Jul 31, 2026	Dimensional ETF Trust, not summed
21.2	U.S. MICRO CAP PORTFOLIO Fund S000000948 · Registered fund · Jul 31, 2026 DFA INVESTMENT DIMENSIONS GROUP INC, not summed	46,660	0.08%	—	Jul 31, 2026	DFA INVESTMENT DIMENSIONS GROUP INC, not summed
21.3	Dimensional U.S. Targeted Value ETF Fund S000070901 · Registered fund · Jul 31, 2026 Dimensional ETF Trust, not summed	25,054	0.04%	—	Jul 31, 2026	Dimensional ETF Trust, not summed
21.4	U.S. Sustainability Targeted Value Portfolio Fund S000068937 · Registered fund · Jul 31, 2026 DFA INVESTMENT DIMENSIONS GROUP INC, not summed	15,413	0.03%	—	Jul 31, 2026	DFA INVESTMENT DIMENSIONS GROUP INC, not summed
21.5	Dimensional VA U.S. Targeted Value Portfolio Fund S000000953 · Registered fund · Jul 31, 2026 DFA INVESTMENT DIMENSIONS GROUP INC, not summed	15,128	0.03%	—	Jul 31, 2026	DFA INVESTMENT DIMENSIONS GROUP INC, not summed
22	GOLDMAN SACHS GROUP INC 13F CIK 886982 · Holding company · Jun 30, 2026 carried, not yet filed for the newest quarter	256,985	0.44%	+256,985	Jun 30, 2026	carried, not yet filed for the newest quarter
23	STATE STREET CORP 13F CIK 93751 · Bank · Jun 30, 2026 carried, not yet filed for the newest quarter	214,751	0.37%	0	Jun 30, 2026	carried, not yet filed for the newest quarter
24	Zack Debra Insider CIK 1807743 · Aug 3, 2026 Chief Medical Officer, issuer-wide	162,311	0.28%	—	Aug 3, 2026	Chief Medical Officer, issuer-wide
25	JANE STREET GROUP, LLC 13F CIK 1595888 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	158,097	0.27%	+51,752	Jun 30, 2026	carried, not yet filed for the newest quarter
26	UBS Group AG 13F CIK 1610520 · Bank · Jun 30, 2026 carried, not yet filed for the newest quarter	139,680	0.24%	+136,671	Jun 30, 2026	carried, not yet filed for the newest quarter
27	BRIDGEWAY CAPITAL MANAGEMENT, LLC 13F CIK 1107261 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	114,800	0.20%	0	Jun 30, 2026	carried, not yet filed for the newest quarter
27.1	Ultra-Small Company Market Fund Fund S000004424 · Registered fund · Jun 30, 2026 Bridgeway Funds, Inc., not summed	64,800	0.11%	0	Jun 30, 2026	Bridgeway Funds, Inc., not summed
27.2	Omni Small-Cap Value Fund Fund S000033567 · Registered fund · Jun 30, 2026 Bridgeway Funds, Inc., not summed	50,000	0.09%	0	Jun 30, 2026	Bridgeway Funds, Inc., not summed
28	NORTHERN TRUST CORP 13F CIK 73124 · Bank · Jun 30, 2026 carried, not yet filed for the newest quarter	108,274	0.19%	-12,710	Jun 30, 2026	carried, not yet filed for the newest quarter
29	Point72 Asset Management, L.P. 13F CIK 1603466 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	104,377	0.18%	+44,709	Jun 30, 2026	carried, not yet filed for the newest quarter
30	Ionic Capital Management LLC 13F CIK 1386462 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	102,698	0.18%	-93,241	Jun 30, 2026	carried, not yet filed for the newest quarter
31	Deshpande Milind Insider CIK 1378588 · Jun 23, 2026 Director, issuer-wide	101,454	0.17%	+10,000	Jun 23, 2026	Director, issuer-wide
32	Federation des caisses Desjardins du Quebec 13F CIK 2022297 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	91,900	0.16%	+91,900	Jun 30, 2026	carried, not yet filed for the newest quarter
33	Jackson Scott Thomas Insider CIK 1566617 · Jun 23, 2026 Director, issuer-wide	85,000	0.15%	+10,000	Jun 23, 2026	Director, issuer-wide
34	Pottage John C Jr Insider CIK 1378587 · Jun 23, 2026 Director, issuer-wide	85,000	0.15%	+10,000	Jun 23, 2026	Director, issuer-wide
35	Smith Cynthia Insider CIK 1609480 · Jun 23, 2026 Director, issuer-wide	85,000	0.15%	+10,000	Jun 23, 2026	Director, issuer-wide
36	THOMAS FRANK E Insider CIK 1242616 · Jun 23, 2026 Director, issuer-wide	85,000	0.15%	+10,000	Jun 23, 2026	Director, issuer-wide
37	Tregoning Kathleen Insider CIK 1830764 · Jun 23, 2026 Director, issuer-wide	85,000	0.15%	+10,000	Jun 23, 2026	Director, issuer-wide
38	VINK PATRICK V.J.J. Insider CIK 1557501 · Jun 23, 2026 Director, issuer-wide	85,000	0.15%	+10,000	Jun 23, 2026	Director, issuer-wide
39	Shay Capital LLC 13F CIK 1723643 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	72,391	0.12%	+2,037	Jun 30, 2026	carried, not yet filed for the newest quarter
40	Invesco Ltd. 13F CIK 914208 · Investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	64,245	0.11%	+18,871	Jun 30, 2026	carried, not yet filed for the newest quarter
40.1	Invesco NASDAQ Future Gen 200 ETF Fund S000077288 · Registered fund · May 31, 2026 Invesco Exchange-Traded Fund Trust II, not summed	35,591	0.06%	+8,062	May 31, 2026	Invesco Exchange-Traded Fund Trust II, not summed
40.2	Invesco RAFI US 1500 Small-Mid ETF Fund S000013120 · Registered fund · Jul 31, 2026 Invesco Exchange-Traded Fund Trust, not summed	26,957	0.05%	+14,263	Jul 31, 2026	Invesco Exchange-Traded Fund Trust, not summed
41	SIMPLEX TRADING, LLC 13F CIK 1488542 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	61,312	0.11%	+31,008	Jun 30, 2026	carried, not yet filed for the newest quarter
42	ACUITAS US MICROCAP FUND Fund S000045890 · Registered fund · Jun 30, 2026 FORUM FUNDS II, not summed	56,457	0.10%	—	Jun 30, 2026	FORUM FUNDS II, not summed
43	Verdad Advisers, LP 13F CIK 1812822 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	51,335	0.09%	+17,880	Jun 30, 2026	carried, not yet filed for the newest quarter
44	XTX Topco Ltd 13F CIK 1828301 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	50,536	0.09%	+50,536	Jun 30, 2026	carried, not yet filed for the newest quarter
45	AMERICAN CENTURY COMPANIES INC 13F CIK 748054 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	36,811	0.06%	+36,811	Jun 30, 2026	carried, not yet filed for the newest quarter
46	Capital Asset Advisory Services LLC 13F CIK 1666024 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	32,548	0.06%	0	Jun 30, 2026	carried, not yet filed for the newest quarter
47	Three Seasons Wealth, LLC 13F CIK 2044495 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	30,000	0.05%	0	Jun 30, 2026	carried, not yet filed for the newest quarter
48	CHARLES SCHWAB INVESTMENT MANAGEMENT INC 13F CIK 884546 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	28,565	0.05%	0	Jun 30, 2026	carried, not yet filed for the newest quarter
48.1	Schwab Total Stock Market Index Fund Fund S000005913 · Registered fund · Jul 31, 2026 SCHWAB CAPITAL TRUST, not summed	28,565	0.05%	0	Jul 31, 2026	SCHWAB CAPITAL TRUST, not summed
49	Vanguard Global Advisers, LLC 13F CIK 1811242 · Registered investment adviser · Jun 30, 2026 carried, not yet filed for the newest quarter	25,446	0.04%	0	Jun 30, 2026	carried, not yet filed for the newest quarter
50	Global Retirement Partners, LLC 13F CIK 1749744 · Unknown · Jun 30, 2026 carried, not yet filed for the newest quarter	25,000	0.04%	—	Jun 30, 2026	carried, not yet filed for the newest quarter

5 more nested rows are not shown here; Every filing lists them all.

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 80 holders

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Key facts CIK 1701108 CUSIP 84833T103 13F (30d) 4 filings 4 filers Visit website Investor relations