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Spero Therapeutics, Inc. (SPRO) institutional ownership

Latest close $1.17 Jul 31, 2026
Market cap$169M 52-week range SectorHealthcare
Funds holding · Q1 2026
39
reported SPRO position changes
Top owners · Q2 2026
No disclosed owners are available.
Institutional activity · Q1 2026
Activity unavailable N/A
18 buyers · 21 sellers

Spero Therapeutics, Inc. (SPRO) price and institutional activity

Dates

Q1 2026

$0 bought by 18 investors
Two Sigma Investments, LPMarshall Wace, LLP +16 more
$0 sold by 21 investors
Informed Momentum Co LLCTwo Sigma Advisers, LP +19 more
Bought Sold Totals per quarter; hover a bar for the names.

Spero Therapeutics, Inc. (SPRO) institutional activity · 39

Investor Type Est. change Change Δ Own Date
Two Sigma Investments, LP · Added
Change +513K Δ Own +137.7% Date Q1 2026
Two Sigma Investments, LP Added· Q1 2026 +513K +137.7% Q1 2026
Informed Momentum Co LLC · Exited
Change −218K Δ Own −100.0% Date Q1 2026
Informed Momentum Co LLC Exited· Q1 2026 −218K −100.0% Q1 2026
Two Sigma Advisers, LP · Exited
Change −217K Δ Own −100.0% Date Q1 2026
Two Sigma Advisers, LP Exited· Q1 2026 −217K −100.0% Q1 2026
Anson Funds Management LP · Reduced
Change −203K Date Q1 2026
Anson Funds Management LP Reduced· Q1 2026 −203K Q1 2026
Marshall Wace, LLP · New
Change +157K Date Q1 2026
Marshall Wace, LLP New· Q1 2026 +157K Q1 2026
Intrepid Family Office LLC · Reduced
Change −149K Date Q1 2026
Intrepid Family Office LLC Reduced· Q1 2026 −149K Q1 2026
Adar1 Capital Management, LLC · Exited
Change −114K Δ Own −100.0% Date Q1 2026
Adar1 Capital Management, LLC Exited· Q1 2026 −114K −100.0% Q1 2026
UBS Group AG · Reduced
Change −113K Date Q1 2026
UBS Group AG Reduced· Q1 2026 −113K Q1 2026
Gsa Capital Partners LLP · Added
Change +99K Date Q1 2026
Gsa Capital Partners LLP Added· Q1 2026 +99K Q1 2026
Omers Administration Corp · Reduced
Change −92K Date Q1 2026
Omers Administration Corp Reduced· Q1 2026 −92K Q1 2026
Renaissance Technologies LLC Reduced· Q1 2026 −90K −7.1% Q1 2026
Squarepoint Ops LLC · Added
Change +75K Date Q1 2026
Squarepoint Ops LLC Added· Q1 2026 +75K Q1 2026
Jane Street Group, LLC · Reduced
Change −52K Date Q1 2026
Jane Street Group, LLC Reduced· Q1 2026 −52K Q1 2026
Susquehanna International Group, LLP · Added
Change +39K Date Q1 2026
Susquehanna International Group, LLP Added· Q1 2026 +39K Q1 2026
Verdad Advisers, LP · New
Change +33K Date Q1 2026
Verdad Advisers, LP New· Q1 2026 +33K Q1 2026
Data through Q1 2026 · filed May 19, 2026
15 of 39

Famous investor activity in Spero Therapeutics, Inc. (SPRO)

Spero Therapeutics, Inc. (SPRO) insider trading

Company insiders, action and economics first; trade and filed dates last.
Dates
Insider Title Type Price Qty Value Owned ΔOwn Trade date Filed date
Deshpande Milind · Director 2 operations 30K
Owned 20K Trade date Jun 23, 2026 Filed date Jun 25, 2026
Deshpande Milind Director 2 operations 30K 20K Jun 23, 2026 Jun 25, 2026
Tregoning Kathleen · Director 2 operations 30K
Owned 20K Trade date Jun 23, 2026 Filed date Jun 25, 2026
Tregoning Kathleen Director 2 operations 30K 20K Jun 23, 2026 Jun 25, 2026
Smith Cynthia · Director 2 operations 30K
Owned 20K Trade date Jun 23, 2026 Filed date Jun 25, 2026
Smith Cynthia Director 2 operations 30K 20K Jun 23, 2026 Jun 25, 2026
Vink Patrick V.j.j. · Director 2 operations 30K
Owned 20K Trade date Jun 23, 2026 Filed date Jun 25, 2026
Vink Patrick V.j.j. Director 2 operations 30K 20K Jun 23, 2026 Jun 25, 2026
Thomas Frank E. · Director 2 operations 30K
Owned 20K Trade date Jun 23, 2026 Filed date Jun 25, 2026
Thomas Frank E. Director 2 operations 30K 20K Jun 23, 2026 Jun 25, 2026
Jackson Scott Thomas · Director 2 operations 30K
Owned 20K Trade date Jun 23, 2026 Filed date Jun 25, 2026
Jackson Scott Thomas Director 2 operations 30K 20K Jun 23, 2026 Jun 25, 2026
Pottage John C. Jr · Director 2 operations 30K
Owned 20K Trade date Jun 23, 2026 Filed date Jun 25, 2026
Pottage John C. Jr Director 2 operations 30K 20K Jun 23, 2026 Jun 25, 2026
Rajavelu Esther · Officer Sell −$63K
Price $2.51 Qty −25K Owned 987K Trade date May 4, 2026 Filed date May 6, 2026
Rajavelu Esther Officer Sell $2.51 −25K −$63K 987K May 4, 2026 May 6, 2026
Rajavelu Esther · Officer 2 operations −$207K
Price $2.36 Qty −88K Owned 1.0M Trade date Feb 6, 2026 Filed date Feb 9, 2026
Rajavelu Esther Officer 2 operations $2.36 −88K −$207K 1.0M Feb 6, 2026 Feb 9, 2026
Keutzer Timothy · Officer Sell −$44K
Price $2.36 Qty −19K Owned 743K Trade date Feb 6, 2026 Filed date Feb 9, 2026
Keutzer Timothy Officer Sell $2.36 −19K −$44K 743K Feb 6, 2026 Feb 9, 2026
Keutzer Timothy · Officer Sell −$8K
Price $2.24 Qty −3K Owned 761K Trade date Feb 4, 2026 Filed date Feb 5, 2026
Keutzer Timothy Officer Sell $2.24 −3K −$8K 761K Feb 4, 2026 Feb 5, 2026
Keutzer Timothy · Officer Sell −$52K
Price $2.14 Qty −24K Owned 765K Trade date Feb 3, 2026 Filed date Feb 5, 2026
Keutzer Timothy Officer Sell $2.14 −24K −$52K 765K Feb 3, 2026 Feb 5, 2026
Keutzer Timothy · Officer Sell −$42K
Price $2.20 Qty −19K Owned 789K Trade date Feb 2, 2026 Filed date Feb 5, 2026
Keutzer Timothy Officer Sell $2.20 −19K −$42K 789K Feb 2, 2026 Feb 5, 2026
Keutzer Timothy · Officer 2 operations 205K
Owned 137K Trade date Feb 2, 2026 Filed date Feb 5, 2026
Keutzer Timothy Officer 2 operations 205K 137K Feb 2, 2026 Feb 5, 2026
Rajavelu Esther · Officer Sell −$41K
Price $2.20 Qty −18K Owned 1.1M Trade date Feb 2, 2026 Filed date Feb 4, 2026
Rajavelu Esther Officer Sell $2.20 −18K −$41K 1.1M Feb 2, 2026 Feb 4, 2026
15 of 19
15 of 19 Sign in to continue to older insider transactions.

Spero Therapeutics, Inc. (SPRO) activist and large shareholders

Dates
Owner/Filer identity Shares reported % of shares outstanding Filing date
Gsk PLC 9.2M
% of shares outstanding 17.8% Filing date Jan 20, 2023
Gsk PLC 9.2M 17.8% Jan 20, 2023
Pfizer Inc 2.4M
% of shares outstanding 7.4% Filing date Jul 9, 2021
Pfizer Inc 2.4M 7.4% Jul 9, 2021
Aquilo Capital Management, LLC 1.6M
% of shares outstanding 5.1% Filing date Mar 9, 2022
Aquilo Capital Management, LLC 1.6M 5.1% Mar 9, 2022
Atlas Venture Fund Ix, L.P. 1.4M
% of shares outstanding 4.3% Filing date Jan 25, 2022
Atlas Venture Fund Ix, L.P. 1.4M 4.3% Jan 25, 2022
Anson Funds Management LP 1.6M
% of shares outstanding 2.9% Filing date Aug 14, 2025
Anson Funds Management LP 1.6M 2.9% Aug 14, 2025
BlackRock Inc. 691K
% of shares outstanding 2.1% Filing date Jul 8, 2022
BlackRock Inc. 691K 2.1% Jul 8, 2022
6 of 6

Spero Therapeutics, Inc. (SPRO) ownership FAQ

Who owns SPRO?

39 reporting institutions disclosed SPRO position changes in the Q1 2026 snapshot.

How is institutional activity calculated?

For each manager, WhoBought compares accepted consecutive 13F share counts. Share change is current shares minus prior shares. Estimated dollar change is that signed share change multiplied by the split-adjusted quarter-mean close. The activity table on this page uses Q1 2026.

What are activist and large shareholder filings?

An investor crossing 5% of a share class generally files Schedule 13D for activist intent or Schedule 13G for a passive position. The technical form names appear here rather than in the activity rows.

Where does this data come from?

Ownership and institutional activity come from SEC Form 13F filings. Insider activity comes from SEC Form 4, and large-shareholder activity from SEC Schedules 13D and 13G. FMP supplies price data only. Company logos use the local verified Parqet cache with one shared fallback.

Why are ownership reports delayed?

Form 13F is a quarterly disclosure and is normally filed after the quarter ends. Every ownership and activity value therefore names its represented period; it is not presented as a live position.

How are missing table values shown?

A muted dash marks a missing table value. It means the filing omitted the value, comparable data is unavailable, or no prior position exists for comparison.