Spero Therapeutics, Inc. - SPRO
Detailed investor-level table based on 13F positions.
Early Q1 2026 data: only 2 institutional holders reported so far. The full shareholder list will grow as more funds file with the SEC.
Methodology:
Market value and % of portfolio use SEC reported VALUE ($000).
For PUT/CALL positions this reflects reported underlying exposure, not premium cash paid/received.
Details.
Rows: 0
| Investor | History | Status | Shares held | Market value ($000) | % of portfolio | Previous % | Rank | Change in shares | % change in shares | Source | Date reported |
|---|---|---|---|---|---|---|---|---|---|---|---|
| GSK plc | History | New | 9,190,606 | 21,414 | 2.68% | — | 1 | +9,190,606 | New | Q4 2025 | Feb 12, 2026 |
| PFIZER INC | History | No change | 2,362,348 | 5,504 | 2.33% | 1.02% | 2 | 0 | 0.0% | Q4 2025 | Feb 12, 2026 |
| VANGUARD GROUP INC | History | Added to | 2,083,462 | 4,854 | 0.0% | 0.0% | 3 | +93,607 | 4.7% | Q4 2025 | Jan 29, 2026 |
| RENAISSANCE TECHNOLOGIES LLC | History | Reduced | 1,279,522 | 2,981 | 0.0% | 0.0% | 4 | -173,243 | -11.93% | Q4 2025 | Feb 12, 2026 |
| Alphabet Inc. | History | No change | 889,979 | 2,073 | 0.08% | 0.07% | 5 | 0 | 0.0% | Q4 2025 | Feb 13, 2026 |
| Anson Funds Management LP | History | Reduced | 625,062 | 1,456 | 0.14% | 0.27% | 6 | -978,507 | -61.02% | Q4 2025 | Feb 17, 2026 |
| GEODE CAPITAL MANAGEMENT, LLC | History | Added to | 529,195 | 1,233 | 0.0% | 0.0% | 7 | +1,718 | 0.33% | Q4 2025 | Feb 09, 2026 |
| CITADEL ADVISORS LLC | History | Added to | 470,964 | 1,097 | 0.0% | 0.0% | 8 | +416,164 | 759.42% | Q4 2025 | Feb 17, 2026 |
| BlackRock, Inc. | History | Reduced | 433,616 | 1,010 | 0.0% | 0.0% | 9 | -1,152 | -0.26% | Q4 2025 | Feb 12, 2026 |
| TWO SIGMA INVESTMENTS, LP | History | Added to | 372,570 | 868 | 0.0% | 0.0% | 10 | +323,171 | 654.21% | Q4 2025 | Feb 17, 2026 |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | History | Added to | 293,700 | 684 | 0.0% | 0.0% | 11 | +282,800 | 2594.5% | Q4 2025 | Feb 17, 2026 |
| Informed Momentum Co LLC | History | Reduced | 218,084 | 508 | 0.06% | 0.06% | 12 | -64,361 | -22.79% | Q4 2025 | Feb 12, 2026 |
| TWO SIGMA ADVISERS, LP | History | New | 216,600 | 504 | 0.0% | — | 13 | +216,600 | New | Q4 2025 | Feb 17, 2026 |
| STATE STREET CORP | History | Added to | 210,151 | 489 | 0.0% | 0.0% | 14 | +19,200 | 10.05% | Q4 2025 | Feb 13, 2026 |
| JANE STREET GROUP, LLC | History | Added to | 196,944 | 458 | 0.0% | 0.0% | 15 | +153,956 | 358.14% | Q4 2025 | Feb 12, 2026 |
| Ionic Capital Management LLC | History | Reduced | 195,939 | 456 | 0.06% | 0.04% | 16 | -12,786 | -6.13% | Q4 2025 | Feb 17, 2026 |
| GSA CAPITAL PARTNERS LLP | History | Added to | 178,930 | 417 | 0.04% | 0.02% | 17 | +72,036 | 67.39% | Q4 2025 | Feb 06, 2026 |
| INTREPID FAMILY OFFICE LLC | History | Added to | 165,000 | 384 | 0.33% | 0.17% | 18 | +55,000 | 50.0% | Q4 2025 | Feb 17, 2026 |
| SEI INVESTMENTS CO | History | New | 132,010 | 307 | 0.0% | — | 19 | +132,010 | New | Q4 2025 | Feb 13, 2026 |
| OMERS ADMINISTRATION Corp | History | New | 131,127 | 305 | 0.0% | — | 20 | +131,127 | New | Q4 2025 | Feb 13, 2026 |
| NORTHERN TRUST CORP | History | Reduced | 120,984 | 281 | 0.0% | 0.0% | 21 | -8,659 | -6.68% | Q4 2025 | Feb 17, 2026 |
| Squarepoint Ops LLC | History | New | 119,434 | 278 | 0.0% | — | 22 | +119,434 | New | Q4 2025 | Feb 13, 2026 |
| UBS Group AG | History | Added to | 116,447 | 271 | 0.0% | 0.0% | 23 | +89,346 | 329.68% | Q4 2025 | Jan 29, 2026 |
| BRIDGEWAY CAPITAL MANAGEMENT, LLC | History | No change | 114,800 | 267 | 0.01% | 0.0% | 24 | 0 | 0.0% | Q4 2025 | Feb 17, 2026 |
| ADAR1 Capital Management, LLC | History | Reduced | 113,839 | 265 | 0.02% | 0.02% | 25 | -1,700 | -1.47% | Q4 2025 | Feb 18, 2026 |
| Shay Capital LLC | History | Reduced | 60,289 | 140 | 0.01% | 0.01% | 26 | -3,378 | -5.31% | Q4 2025 | Feb 17, 2026 |
| Point72 Asset Management, L.P. | History | New | 43,579 | 101 | 0.0% | — | 27 | +43,579 | New | Q4 2025 | Feb 17, 2026 |
| Quadrature Capital Ltd | History | New | 37,799 | 88 | 0.0% | — | 28 | +37,799 | New | Q4 2025 | Feb 17, 2026 |
| SIMPLEX TRADING, LLC | History | Added to | 35,686 | 83 | 0.0% | 0.0% | 29 | +28,068 | 368.44% | Q4 2025 | Feb 11, 2026 |
| Capital Asset Advisory Services LLC | History | No change | 32,548 | 81 | 0.0% | 0.0% | 30 | 0 | 0.0% | Q4 2025 | Jan 09, 2026 |
| AXXCESS WEALTH MANAGEMENT, LLC | History | No change | 32,548 | 75 | 0.0% | 0.0% | 31 | 0 | 0.0% | Q4 2025 | Feb 19, 2026 |
| DIMENSIONAL FUND ADVISORS LP | History | Added to | 29,768 | 69 | 0.0% | 0.0% | 32 | +774 | 2.67% | Q4 2025 | Feb 12, 2026 |
| Three Seasons Wealth, LLC | History | No change | 30,000 | 69 | 0.01% | 0.01% | 33 | 0 | 0.0% | Q4 2025 | Jan 15, 2026 |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC | History | No change | 28,565 | 66 | 0.0% | 0.0% | 34 | 0 | 0.0% | Q4 2025 | Feb 13, 2026 |
| Invesco Ltd. | History | Added to | 24,705 | 57 | 0.0% | 0.0% | 35 | +2,605 | 11.79% | Q4 2025 | Feb 19, 2026 |
| MILLENNIUM MANAGEMENT LLC | History | New | 24,107 | 56 | 0.0% | — | 36 | +24,107 | New | Q4 2025 | Feb 17, 2026 |
| Assenagon Asset Management S.A. | History | Reduced | 18,636 | 43 | 0.0% | 0.0% | 37 | -18,357 | -49.62% | Q4 2025 | Jan 09, 2026 |
| Torrey Growth & Income Advisors | History | Added to | 17,025 | 39 | 0.01% | 0.01% | 38 | +1,250 | 7.92% | Q4 2025 | Feb 17, 2026 |
| XTX Topco Ltd | History | Reduced | 15,175 | 35 | 0.0% | 0.0% | 39 | -18,626 | -55.1% | Q4 2025 | Feb 17, 2026 |
| Texas Yale Capital Corp. | History | No change | 10,000 | 23 | 0.0% | 0.0% | 40 | 0 | 0.0% | Q4 2025 | Feb 10, 2026 |
| Tower Research Capital LLC (TRC) | History | New | 7,215 | 16 | 0.0% | — | 41 | +7,215 | New | Q4 2025 | Feb 17, 2026 |
| JONES FINANCIAL COMPANIES LLLP | History | New | 6,477 | 15 | 0.0% | — | 42 | +6,477 | New | Q4 2025 | Feb 17, 2026 |
| JPMORGAN CHASE & CO | History | Added to | 5,373 | 12 | 0.0% | — | 43 | +5,137 | 2176.69% | Q4 2025 | Feb 11, 2026 |
| FNY Investment Advisers, LLC | History | No change | 5,300 | 12 | 0.0% | 0.0% | 44 | 0 | 0.0% | Q4 2025 | Jan 16, 2026 |
| CULLEN/FROST BANKERS, INC. | History | New | 3,000 | 6 | 0.0% | — | 45 | +3,000 | New | Q4 2025 | Feb 06, 2026 |
| BANK OF AMERICA CORP /DE/ | History | Added to | 744 | 1 | 0.0% | 0.0% | 46 | +11 | 1.5% | Q4 2025 | Feb 17, 2026 |
| ARROWSTREET CAPITAL, LIMITED PARTNERSHIP | History | Closed out | 0 | 0 | — | 0.0% | — | -150,516 | -100.0% | Q3 2025 | Nov 13, 2025 |
| MORGAN STANLEY | History | Reduced | 313 | 0 | — | 0.0% | — | -43,065 | -99.28% | Q4 2025 | Feb 13, 2026 |
| AMERICAN CENTURY COMPANIES INC | History | Closed out | 0 | 0 | — | 0.0% | — | -40,219 | -100.0% | Q3 2025 | Nov 12, 2025 |
| Rangeley Capital, LLC | History | Closed out | 0 | 0 | — | 0.05% | — | -30,000 | -100.0% | Q3 2025 | Nov 14, 2025 |
| GROUP ONE TRADING LLC | History | Closed out | 0 | 0 | — | 0.0% | — | -16,879 | -100.0% | Q3 2025 | Nov 12, 2025 |
| FMR LLC | History | Closed out | 0 | 0 | — | 0.0% | — | -550 | -100.0% | Q3 2025 | Nov 13, 2025 |
| NewEdge Advisors, LLC | History | Closed out | 0 | 0 | — | — | — | -100 | -100.0% | Q3 2025 | Nov 17, 2025 |
| CITIGROUP INC | History | New | 17 | 0 | — | — | — | +17 | New | Q4 2025 | Feb 13, 2026 |
| SageView Advisory Group, LLC | History | New | 17 | 0 | — | — | — | +17 | New | Q4 2025 | Feb 17, 2026 |
| Farther Finance Advisors, LLC | History | New | 10 | 0 | — | — | — | +10 | New | Q4 2025 | Jan 23, 2026 |
| SBI Securities Co., Ltd. | History | Reduced | 9 | 0 | — | — | — | -1 | -10.0% | Q4 2025 | Feb 03, 2026 |
| US BANCORP \DE\ | History | No change | 151 | 0 | — | — | — | 0 | 0.0% | Q4 2025 | Jan 30, 2026 |
| WELLS FARGO & COMPANY/MN | History | No change | 200 | 0 | — | — | — | 0 | 0.0% | Q4 2025 | Feb 13, 2026 |
| BNP PARIBAS FINANCIAL MARKETS | History | No change | 40 | 0 | — | — | — | 0 | 0.0% | Q4 2025 | Feb 10, 2026 |
| OSAIC HOLDINGS, INC. | History | No change | 290 | 0 | — | — | — | 0 | 0.0% | Q4 2025 | Feb 17, 2026 |
| Rockefeller Capital Management L.P. | History | No change | 200 | 0 | — | — | — | 0 | 0.0% | Q4 2025 | Mar 16, 2026 |