Spero Therapeutics SPRO Institutional Ownership

NASDAQ SPRO

$1.17 -0.05 (-4.10%)

At close: Oct 21, 2026 · 4:00 PM EDT

Institutions by Trading Activity

60 Institutions

Increased 38 63.3%

Unchanged 16 26.7%

Reduced 6 10.0%

Ownership Statistics

13F · as of 30 Jun, 2026

Institutional Ownership

36.90%

▲+1.24 pp QoQ

Shares Held by Institutions

21.45Mn

of 58.15Mn outstanding

▲+3.93% QoQ

Shares Outstanding

58.15Mn

36.69Mn held outside 13F filers

Institutional Investors

filed 13F for Jun 2026

▲+10 vs prior quarter

Net Shares Added (QoQ)

+810.53K

accumulated since last quarter

Value of Holdings

$26.17Mn

reported market value

Shares Owned by Institutions

Shares held % of outstanding

Latest —

Average ownership —

Peak ownership —

Shares Purchased/Sold by Institutions

Accumulated Distributed

Latest quarter —

Net over range —

Accumulating quarters —

Ownership Summary

Updated Oct 10, 2026

Spero Therapeutics, Inc. (NASDAQ:SPRO) counted 60 institutional investors among its 13F-reported shareholders for the quarter ended June 30, 2026.

These investors held 36.90% of Spero Therapeutics' outstanding shares at the end of Q2 2026, up from 35.66% in Q1 2026.
Total shares held in Spero Therapeutics rose 3.93% versus Q1 2026, while the number of holders rose 42.86% versus Q2 2025.
Looking at the 60 holders of SPRO individually, 38 added to their positions, 6 reduced their stakes and 16 left their positions unchanged.
The aggregate institutional position in Spero Therapeutics was 21.45Mn shares at the end of Q2 2026, up 810.53K from the prior quarter and up 10.49Mn from a year earlier.
GSK plc was the top holder of Spero Therapeutics as of June 30, 2026, with 9.19Mn shares, or 15.81% of shares outstanding.
The largest position increases in SPRO for Q2 2026 were by Susquehanna International Group, LLP (+426.18K shares), Dimensional Fund Advisors LP (+245.05K shares), Vanguard Capital Management LLC (+236.35K shares), BlackRock, Inc. (+161.2K shares) and UBS Group AG (+136.67K shares).
On the other side, among holders that kept a position in Spero Therapeutics, the largest reductions in Q2 2026 came from Two Sigma Investments, LP (-502.82K shares), Renaissance Technologies LLC (-241.33K shares), Ionic Capital Management LLC (-93.24K shares), Northern Trust Corp (-12.71K shares) and Citigroup Inc (-9.51K shares).
According to Business Quant data, the leading holders of SPRO for Q2 2026 were GSK plc (9.19Mn shares), Pfizer Inc (2.36Mn shares), Vanguard Capital Management LLC (2.04Mn shares), Renaissance Technologies LLC (947.9K shares), Alphabet Inc. (889.98K shares), Susquehanna International Group, LLP (759.29K shares), BlackRock, Inc. (594.4K shares), Geode Capital Management, LLC (566.33K shares), Raymond James Financial Inc (521.71K shares) and Two Sigma Investments, LP (382.81K shares).

Form 13F Holdings

61 Institutional Holders

Report period 30 Jun, 2026

Total shares held 21.45Mn

Of outstanding 36.90%

#	Institution	CIK	Shares Held	% of Outstanding	Change (QoQ)	Change (%)	Value (USD)
1	GSK plc	0001131399	9,190,606	15.81%	0	0.00%	$20.31Mn
2	Pfizer Inc	0000078003	2,362,348	4.06%	0	0.00%	$5.34Mn
3	VANGUARD CAPITAL MANAGEMENT LLC	0002100119	2,036,226	3.50%	▲236,346	+13.13%	$4.50Mn
4	RENAISSANCE TECHNOLOGIES LLC	0001037389	947,904	1.63%	▼241,331	-20.29%	$2.09Mn
5	Alphabet Inc.	0001652044	889,979	1.53%	0	0.00%	$1.97Mn
6	SUSQUEHANNA INTERNATIONAL GROUP, LLP	0001446194	759,290	1.31%	▲426,175	+127.94%	$1.68Mn
7	BlackRock, Inc.	0002012383	594,404	1.02%	▲161,202	+37.21%	$1.31Mn
8	GEODE CAPITAL MANAGEMENT, LLC	0001214717	566,329	0.97%	▲46,407	+8.93%	$1.25Mn
9	Raymond James Financial Inc	0000720005	521,705	0.90%	▲521,705	0.00%	$1.15Mn
10	TWO SIGMA INVESTMENTS, LP	0001179392	382,814	0.66%	▼502,817	-56.78%	$846.02K
11	ARROWSTREET CAPITAL, LIMITED PARTNERSHIP	0001164508	332,970	0.57%	▲332,970	0.00%	$735.86K
12	VANGUARD FIDUCIARY TRUST CO	0000933478	287,648	0.49%	▲23,533	+8.91%	$635.70K
13	GSA CAPITAL PARTNERS LLP	0001362033	285,906	0.49%	▲7,602	+2.73%	$632
14	DIMENSIONAL FUND ADVISORS LP	0000354204	274,820	0.47%	▲245,052	+823.21%	$607.62K
15	Goldman Sachs Group Inc	0000886982	256,985	0.44%	▲256,985	0.00%	$567.94K
16	State Street Corp	0000093751	214,751	0.37%	0	0.00%	$474.60K
17	JANE STREET GROUP, LLC	0001595888	158,097	0.27%	▲51,752	+48.66%	$349.39K
18	UBS Group AG	0001610520	139,680	0.24%	▲136,671	+4,542.07%	$308.69K
19	BRIDGEWAY CAPITAL MANAGEMENT, LLC	0001107261	114,800	0.20%	0	0.00%	$253.71K
20	Northern Trust Corp	0000073124	108,274	0.19%	▼12,710	-10.51%	$239.29K

Showing 1 to 20 of 61 holders