Spero Therapeutics, Inc. (SPRO) Institutional Ownership

Institutions by Trading Activity

Ownership Statistics

56,280,844Shares Outstanding

21,265,986Shares held by institutions

$56,992,842Value of institutional holdings

37.79%Institutional ownership %

93.33%Shares Changed QoQ

56No. of institutional investors

Shares Owned by Institutions

Shares Purchased/Sold by Institutions

Ownership Summary

Spero Therapeutics, Inc. (NASDAQ:SPRO) has 56 institutional investors that have filed 13F reports for the period ending December 2025.

These investors collectively held 37.8% of Spero Therapeutics's outstanding shares in December 2025, up from 20.0% in September 2025.
They increased total shares held in Spero Therapeutics by 93.33% from the prior quarter, while the number of investors in SPRO increased 12.0% year over year.
Activity in SPRO broke down as 32 buyers, 11 sellers, and 13 unchanged among 56 total holders.
Combined, these investors held 21.27Mn shares in SPRO for December 2025, up by 10.27Mn shares quarter on quarter, and up 5.2Mn shares year over year.
GSK plc is the top holder of Spero Therapeutics as of December 31, 2025, with 9.19Mn shares representing 16.33% of outstanding stock.
Leading buyers of Spero Therapeutics shares for the quarter ending December 2025 were GSK plc (9.19Mn), CITADEL ADVISORS LLC (397.86K), TWO SIGMA INVESTMENTS, LP (323.17K), SUSQUEHANNA INTERNATIONAL GROUP, LLP (293.7K), TWO SIGMA ADVISERS, LP (216.6K).
Top sellers of SPRO stock for the quarter ending December 2025 included Anson Funds Management LP (978.51K), RENAISSANCE TECHNOLOGIES LLC (173.24K), Informed Momentum Co LLC (64.36K), Morgan Stanley (43.06K), Assenagon Asset Management S.A. (18.36K).
Per Business Quant, the top 10 investors in SPRO for the quarter ending December 2025 include GSK plc (9.19Mn), Pfizer Inc (2.36Mn), VANGUARD GROUP INC (2.08Mn), RENAISSANCE TECHNOLOGIES LLC (1.28Mn), Alphabet Inc. (889.98K), Anson Funds Management LP (625.06K), GEODE CAPITAL MANAGEMENT, LLC (529.2K), BlackRock, Inc. (433.62K), CITADEL ADVISORS LLC (397.86K), TWO SIGMA INVESTMENTS, LP (372.57K).

56 Institutional Holders

21,265,986 Total Shares Held

Rows:

Download Data

Owner Name	Date	Shares Held	Change (QoQ)	Change (%)	Value (USD)
GSK plc	31 Dec, 2025	9,190,606	9,190,606	0.00%	$21,414,112.00
Pfizer Inc	31 Dec, 2025	2,362,348	0	0.00%	$5,504,271.00
VANGUARD GROUP INC	31 Dec, 2025	2,083,462	93,607	4.70%	$4,854,466.00
RENAISSANCE TECHNOLOGIES LLC	31 Dec, 2025	1,279,522	-173,243	-11.93%	$2,981,286.00
Alphabet Inc.	31 Dec, 2025	889,979	0	0.00%	$2,073,651.00
Anson Funds Management LP	31 Dec, 2025	625,062	-978,507	-61.02%	$1,456,394.00
GEODE CAPITAL MANAGEMENT, LLC	31 Dec, 2025	529,195	1,718	0.33%	$1,233,298.00
BlackRock, Inc.	31 Dec, 2025	433,616	-1,152	-0.26%	$1,010,326.00
CITADEL ADVISORS LLC	31 Dec, 2025	397,864	397,864	0.00%	$927,024.00
TWO SIGMA INVESTMENTS, LP	31 Dec, 2025	372,570	323,171	654.21%	$868,088.00
SUSQUEHANNA INTERNATIONAL GROUP, LLP	31 Dec, 2025	293,700	293,700	0.00%	$684,321.00
ADAR1 Capital Management, LLC	31 Dec, 2025	227,678	112,139	97.06%	$530,490.00
Informed Momentum Co LLC	31 Dec, 2025	218,084	-64,361	-22.79%	$508,136.00
TWO SIGMA ADVISERS, LP	31 Dec, 2025	216,600	216,600	0.00%	$504,678.00
State Street Corp	31 Dec, 2025	210,151	19,200	10.05%	$489,652.00
Ionic Capital Management LLC	31 Dec, 2025	195,939	-12,786	-6.13%	$456,538.00
GSA CAPITAL PARTNERS LLP	31 Dec, 2025	178,930	72,036	67.39%	$417.00
INTREPID FAMILY OFFICE LLC	31 Dec, 2025	165,000	55,000	50.00%	$384,450.00
JANE STREET GROUP, LLC	31 Dec, 2025	158,344	115,356	268.34%	$368,941.00
Sei Investments Co	31 Dec, 2025	132,010	132,010	0.00%	$307,581.00

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