Spero Therapeutics, Inc. - Common Stock, par value $0.001 per share (SPRO) Institutional Ownership

13F Institutional Holders and Ownership History from Q4 2017 to Q4 2025

Type / Class
Equity / Common Stock, par value $0.001 per share
Symbol
SPRO on Nasdaq
Shares outstanding
55,705,828
Price per share
$2.37
All holders as of 31 Dec 2025
Q4 2025
Total 13F shares
21,119,398
Total reported value
$49,213,763
% of total 13F portfolios
0%
Share change
+658,135
Value change
+$1,640,743
Number of holders
56
Price from insider filings
$2.37
Reported Shares, Excluding Options vs Price
Reported Value, Excluding Options
Total Investors

Significant Owners of Spero Therapeutics, Inc. - Common Stock, par value $0.001 per share (SPRO) based on Schedule 13D/G filings

Filer Ownership Change % Holdings Value Net Change Nb Shares Change % Reporting Name Report Period
GSK plc 16% $6,709,142 9,190,606 GSK PLC 27 Mar 2025
Anson Funds Management LP 2.9% $4,587,932 1,615,469 Anson Funds Management LP 30 Jun 2025

As of 31 Dec 2025, 56 institutional investors reported holding 21,119,398 shares of Spero Therapeutics, Inc. - Common Stock, par value $0.001 per share (SPRO). This represents 38% of the company’s total 55,705,828 outstanding shares.

Top 25 Institutional Shareholders

The largest institutional shareholders of Spero Therapeutics, Inc. - Common Stock, par value $0.001 per share (SPRO) together control 37% of the company’s outstanding shares — a level of ownership often associated with strong institutional conviction and long‑term capital commitment.

Institution Ownership % Shares Held Share Change % Portfolio % Holdings Value
GSK plc 16% 9,190,606 0% 2.7% $21,414,112
Pfizer Inc 4.2% 2,362,348 0% 2.3% $5,504,271
VANGUARD GROUP INC 3.7% 2,083,462 +4.7% 0% $4,854,466
RENAISSANCE TECHNOLOGIES LLC 2.3% 1,279,522 -12% 0% $2,981,286
Alphabet Inc. 1.6% 889,979 0% 0.08% $2,073,651
Anson Funds Management LP 1.1% 625,062 -61% 0.2% $1,456,394
GEODE CAPITAL MANAGEMENT, LLC 0.95% 529,195 +0.33% 0% $1,233,298
BlackRock, Inc. 0.78% 433,616 -0.26% 0% $1,010,326
CITADEL ADVISORS LLC 0.71% 397,864 0% $927,024
TWO SIGMA INVESTMENTS, LP 0.67% 372,570 +654% 0% $868,088
SUSQUEHANNA INTERNATIONAL GROUP, LLP 0.53% 293,700 0% $684,321
Informed Momentum Co LLC 0.39% 218,084 -23% 0.06% $508,136
TWO SIGMA ADVISERS, LP 0.39% 216,600 0% $504,678
STATE STREET CORP 0.38% 210,151 +10% 0% $489,652
Ionic Capital Management LLC 0.35% 195,939 -6.1% 0.45% $456,538
GSA CAPITAL PARTNERS LLP 0.32% 178,930 +67% 0.04% $417,000
INTREPID FAMILY OFFICE LLC 0.3% 165,000 +50% 0.37% $384,450
JANE STREET GROUP, LLC 0.28% 158,344 +268% 0% $368,941
SEI INVESTMENTS CO 0.24% 132,009 0% $307,581
OMERS ADMINISTRATION Corp 0.24% 131,127 0% $305,526
NORTHERN TRUST CORP 0.22% 120,984 -6.7% 0% $281,893
Squarepoint Ops LLC 0.21% 119,434 0% $278,281
UBS Group AG 0.21% 116,447 +330% 0% $271,322
BRIDGEWAY CAPITAL MANAGEMENT, LLC 0.21% 114,800 0% 0.01% $267,484
ADAR1 Capital Management, LLC 0.2% 113,839 -1.5% 0.02% $265,245

Institutional Holders of Spero Therapeutics, Inc. - Common Stock, par value $0.001 per share (SPRO) across Reporting Periods

Period Reported Shares, Excl. Options Value, Excl. Options Value Change Price (Median) Investors
2025 Q4 21,119,398 $49,213,763 +$1,640,743 $2.33 56
2025 Q3 11,311,502 $21,264,964 -$925,483 $1.88 47
2025 Q2 11,078,704 $32,127,617 -$7,947,299 $2.90 44
2025 Q1 15,108,016 $10,875,927 -$477,165 $0.72 38
2024 Q4 15,679,985 $16,148,583 +$400,519 $1.03 50
2024 Q3 12,343,754 $16,539,251 -$2,018,983 $1.34 46
2024 Q2 13,876,978 $18,039,320 +$23,111 $1.30 47
2024 Q1 13,757,012 $23,665,168 -$10,720 $1.72 54
2023 Q4 13,365,697 $19,647,483 +$254,060 $1.47 46
2023 Q3 14,186,051 $17,161,812 -$230,667 $1.21 53
2023 Q2 14,363,122 $20,824,354 +$224,803 $1.45 56
2023 Q1 14,249,435 $20,599,780 -$6,707 $1.45 46
2022 Q4 14,222,474 $24,601,496 -$11,539,486 $1.73 57
2022 Q3 19,852,133 $39,711,772 +$134,944 $2.00 61
2022 Q2 20,944,051 $15,519,733 -$13,723,970 $0.74 60
2022 Q1 20,241,451 $176,086,818 +$3,320,960 $8.70 96
2021 Q4 19,791,141 $316,661,728 +$1,752,850 $16.01 82
2021 Q3 18,370,536 $338,246,936 +$16,477,961 $18.41 87
2021 Q2 16,107,401 $224,862,846 -$15,083,084 $13.96 82
2021 Q1 18,548,675 $273,055,350 +$11,246,827 $14.72 89
2020 Q4 19,088,635 $370,127,115 +$23,864,503 $19.39 87
2020 Q3 16,774,007 $187,077,092 +$55,385,284 $11.16 77
2020 Q2 11,755,382 $159,039,554 +$6,802,405 $13.53 76
2020 Q1 11,530,942 $93,166,538 +$5,358,513 $8.08 60
2019 Q4 10,816,370 $103,998,595 +$4,177,290 $9.61 61
2019 Q3 10,374,836 $109,974,592 -$2,905,980 $10.60 59
2019 Q2 10,642,327 $122,390,354 +$15,770,919 $11.51 60
2019 Q1 9,265,285 $118,611,567 +$3,622,037 $12.81 53
2018 Q4 9,098,891 $56,002,988 -$16,910,081 $6.15 50
2018 Q3 10,749,538 $112,996,000 +$24,528,130 $10.51 51
2018 Q2 8,120,919 $119,131,433 +$30,467 $14.67 42
2018 Q1 7,704,769 $109,789,119 -$578,036 $14.25 34
2017 Q4 7,758,590 $91,157,605 +$91,039,605 $11.75 36