Latest Period
Q1 2026
Security Snapshot
Spero Therapeutics, Inc. - Common Stock, par value $0.001 per share (SPRO) Institutional Ownership
CUSIP: 84833T103
13F Institutional Holders and Ownership History from Q4 2017 to Q1 2026
Institutions Reporting
50
Shares (Excl. Options)
20,643,241
Price
$2.34
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- Security type / class
- Equity / Common Stock, par value $0.001 per share
- Symbol
- SPRO on Nasdaq
- All holders as of 31 Mar 2026
- Q1 2026
- Total 13F shares
- 20,643,241
- Total 13F value
- $48,297,782
- Portfolio coverage rank
- 0%
- Share change
- -482,119
- Value change
- -$1,117,234
- Number of holders
- 50
- Shares outstanding
- 55,705,828
- SEC-reported price per share
- $2.86
- Insider filing price
- $2.86
Latest holder snapshot
5 signals
Issuer context
Names, identifiers, and filing context for this profile.
3 identity fields
13F Shares, Excluding Options vs Price
13F Value, Excluding Options
Total Investors
Key facts
- SPRO - Spero Therapeutics, Inc. - Common Stock, par value $0.001 per share is tracked under CUSIP 84833T103.
- 50 institutions reported positions in Q1 2026.
- 2 significant owners is listed from Schedule 13D/13G reporting.
Change
- Holder count moved from 56 to 50 between Q4 2025 and Q1 2026.
- SEC-reported value moved from $49,213,763 to $48,297,782.
Research use
- You can quickly see who holds this security, then open quarter and manager detail pages for full evidence.
- 13F and Schedule 13D/13G sections are kept together so you can cross-check institutional and beneficial ownership context.
Evidence
Source: SEC Form 13F
Open SEC evidence
Latest holder context comes from 50 institutions filings for Q1 2026.
Security key
84833T103
Latest holder period
Q1 2026
13F holders
50
13D/G owners
2
CIK / CUSIP context first
Open Q1 2026 holders
SPRO full holder history
Spero Therapeutics, Inc. SEC filings
Spero Therapeutics, Inc. company facts
Spero Therapeutics, Inc. insider transactions
Broader feeds
Recent Quarterly Holder Reports
Open recent reporting periods for CUSIP 84833T103:
13D/G owners
Significant owners
Large-stake holder rows connected to Schedule 13D/G evidence.
Rows
2
Security
SPRO
| 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 Mar 2026, 50 institutional investors reported holding 20,643,241 shares of Spero Therapeutics, Inc. - Common Stock, par value $0.001 per share (SPRO). This represents 37% of the company’s total 55,705,828 outstanding shares.
13F concentration
Top 25 institutional shareholders
Largest 13F positions for this security by reported shares and value.
Top holder share
36%
| Institution | Ownership % | Shares Held | Share Change % | Portfolio % | Holdings Value |
|---|---|---|---|---|---|
| GSK plc | 16% | 9,190,606 | 0% | 3.6% | $21,506,018 |
| Pfizer Inc | 4.2% | 2,362,348 | 0% | 2.3% | $5,504,271 |
| VANGUARD CAPITAL MANAGEMENT LLC | 3.2% | 1,799,880 | 0% | 0% | $4,211,719 |
| RENAISSANCE TECHNOLOGIES LLC | 2.1% | 1,189,235 | -7.1% | 0% | $2,782,810 |
| Alphabet Inc. | 1.6% | 889,979 | 0% | 0.05% | $2,082,551 |
| TWO SIGMA INVESTMENTS, LP | 1.6% | 885,631 | +138% | 0% | $2,072,377 |
| GEODE CAPITAL MANAGEMENT, LLC | 0.93% | 519,922 | -1.8% | 0% | $1,217,170 |
| BlackRock, Inc. | 0.78% | 433,202 | -0.1% | 0% | $1,013,693 |
| Anson Funds Management LP | 0.76% | 421,956 | -32% | 0.13% | $987,377 |
| CITADEL ADVISORS LLC | 0.68% | 376,458 | -5.4% | 0% | $880,912 |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | 0.6% | 333,115 | +13% | 0% | $779,489 |
| GSA CAPITAL PARTNERS LLP | 0.5% | 278,304 | +56% | 0.04% | $651,000 |
| VANGUARD FIDUCIARY TRUST CO | 0.47% | 264,115 | 0% | 0% | $618,029 |
| STATE STREET CORP | 0.39% | 214,751 | +2.2% | 0% | $502,517 |
| Ionic Capital Management LLC | 0.35% | 195,939 | 0% | 0.38% | $458,497 |
| Squarepoint Ops LLC | 0.35% | 194,301 | +63% | 0% | $454,664 |
| MARSHALL WACE, LLP | 0.28% | 157,072 | 0% | $367,547 | |
| NORTHERN TRUST CORP | 0.22% | 120,984 | 0% | 0% | $283,103 |
| BRIDGEWAY CAPITAL MANAGEMENT, LLC | 0.21% | 114,800 | 0% | 0.01% | $268,632 |
| JANE STREET GROUP, LLC | 0.19% | 106,345 | -33% | 0% | $248,847 |
| Shay Capital LLC | 0.13% | 70,354 | +17% | 0.02% | $164,628 |
| Point72 Asset Management, L.P. | 0.11% | 59,668 | +37% | 0% | $139,623 |
| Invesco Ltd. | 0.08% | 45,374 | +84% | 0% | $106,175 |
| Quadrature Capital Ltd | 0.07% | 40,128 | +6.2% | 0% | $93,900 |
| OMERS ADMINISTRATION Corp | 0.07% | 39,400 | -70% | 0% | $92,196 |
Quarter history
Institutional holders across reporting periods
Holder count, reported shares/value, and median price by quarter.
Periods
34
Latest
Q1 2026
Rows shown
1-25 of 34
| Period | 13F Shares, Excl. Options | Value, Excl. Options | Value Change | Price (Median) | Investors |
|---|---|---|---|---|---|
| 2026 Q1 | 20,643,241 | $48,297,782 | -$1,117,234 | $2.34 | 50 |
| 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 |