CAMBRIDGE, MA
SPERO THERAPEUTICS, INC.SPRO— Latest position per institution from SEC 13F filings
15
Institutional holders
30M
Total shares held
52.25M
Estimated value
1.50M
Avg. position size
GSK PLC
CIK 1131399
Shares
9.19M
Value
21.51M
Filed
Mar 31, 2026
AQUILO CAPITAL MANAGEMENT, LLC
CIK 1591986
Shares
3.40M
Value
6.81K
Filed
Sep 30, 2022
PFIZER INC
CIK 78003
Shares
2.36M
Value
5.50M
Filed
Mar 31, 2026
VANGUARD GROUP INC
CIK 102909
Shares
2.08M
Value
4.85M
Filed
Dec 31, 2025
BVF INC/IL
CIK 1056807
Shares
1.93M
Value
3.86K
Filed
Sep 30, 2022
VANGUARD CAPITAL MANAGEMENT LLC
CIK 2100119
Shares
1.80M
Value
4.21M
Filed
Mar 31, 2026
ATLAS VENTURE ASSOCIATES IX, LLC
CIK 1671207
Shares
1.35M
Value
1.64M
Filed
Sep 30, 2023
RENAISSANCE TECHNOLOGIES LLC
CIK 1037389
Shares
1.19M
Value
2.78M
Filed
Mar 31, 2026
ALPHABET INC.
CIK 1652044
Shares
889.98K
Value
2.08M
Filed
Mar 31, 2026
TWO SIGMA INVESTMENTS, LP
CIK 1179392
Shares
885.63K
Value
2.07M
Filed
Mar 31, 2026
MURCHINSON LTD.
CIK 1838556
Shares
873.91K
Value
629.22K
Filed
Mar 31, 2025
GEODE CAPITAL MANAGEMENT, LLC
CIK 1214717
Shares
519.92K
Value
1.22M
Filed
Mar 31, 2026
ARTAL GROUP S.A.
CIK 1053906
Shares
500K
Value
1K
Filed
Sep 30, 2022
BLACKROCK FINANCE, INC.
CIK 1364742
Shares
483.40K
Value
628.42K
Filed
Jun 30, 2024
NOVO HOLDINGS A/S
CIK 1388325
Shares
468.90K
Value
628.33K
Filed
Sep 30, 2024
BLACKROCK, INC.
CIK 2012383
Shares
433.20K
Value
1.01M
Filed
Mar 31, 2026
CITADEL ADVISORS LLC
CIK 1423053
Shares
425.66K
Value
996.04K
Filed
Mar 31, 2026
ANSON FUNDS MANAGEMENT LP
CIK 1491072
Shares
421.96K
Value
987.38K
Filed
Mar 31, 2026
AMERIPRISE FINANCIAL INC
CIK 820027
Shares
402.96K
Value
592.36K
Filed
Dec 31, 2023
SUSQUEHANNA INTERNATIONAL GROUP, LLP
CIK 1446194
Shares
381.62K
Value
892.98K
Filed
Mar 31, 2026
| # | Institution | CIK | Shares | Est. Value | Period |
|---|---|---|---|---|---|
| 1 | GSK PLC | 1131399 | 9.19M | 21.51M | Mar 31, 2026 |
| 2 | AQUILO CAPITAL MANAGEMENT, LLC | 1591986 | 3.40M | 6.81K | Sep 30, 2022 |
| 3 | PFIZER INC | 78003 | 2.36M | 5.50M | Mar 31, 2026 |
| 4 | VANGUARD GROUP INC | 102909 | 2.08M | 4.85M | Dec 31, 2025 |
| 5 | BVF INC/IL | 1056807 | 1.93M | 3.86K | Sep 30, 2022 |
| 6 | VANGUARD CAPITAL MANAGEMENT LLC | 2100119 | 1.80M | 4.21M | Mar 31, 2026 |
| 7 | ATLAS VENTURE ASSOCIATES IX, LLC | 1671207 | 1.35M | 1.64M | Sep 30, 2023 |
| 8 | RENAISSANCE TECHNOLOGIES LLC | 1037389 | 1.19M | 2.78M | Mar 31, 2026 |
| 9 | ALPHABET INC. | 1652044 | 889.98K | 2.08M | Mar 31, 2026 |
| 10 | TWO SIGMA INVESTMENTS, LP | 1179392 | 885.63K | 2.07M | Mar 31, 2026 |
| 11 | MURCHINSON LTD. | 1838556 | 873.91K | 629.22K | Mar 31, 2025 |
| 12 | GEODE CAPITAL MANAGEMENT, LLC | 1214717 | 519.92K | 1.22M | Mar 31, 2026 |
| 13 | ARTAL GROUP S.A. | 1053906 | 500K | 1K | Sep 30, 2022 |
| 14 | BLACKROCK FINANCE, INC. | 1364742 | 483.40K | 628.42K | Jun 30, 2024 |
| 15 | NOVO HOLDINGS A/S | 1388325 | 468.90K | 628.33K | Sep 30, 2024 |
| 16 | BLACKROCK, INC. | 2012383 | 433.20K | 1.01M | Mar 31, 2026 |
| 17 | CITADEL ADVISORS LLC | 1423053 | 425.66K | 996.04K | Mar 31, 2026 |
| 18 | ANSON FUNDS MANAGEMENT LP | 1491072 | 421.96K | 987.38K | Mar 31, 2026 |
| 19 | AMERIPRISE FINANCIAL INC | 820027 | 402.96K | 592.36K | Dec 31, 2023 |
| 20 | SUSQUEHANNA INTERNATIONAL GROUP, LLP | 1446194 | 381.62K | 892.98K | Mar 31, 2026 |
Data sourced from SEC Form 13F institutional holdings reports. Positions reflect the most recent filing per institution.