Spero Therapeutics, Inc. (SPRO) shareholders
SPRONasdaqPharmaceutical PreparationsFiscal year ends December 31
$1.00−0.00 (-0.01%)
Close on Nov 13, 2026Market cap $58.23MP/E –Yield –
Ownership
Institutional holdings as of Jun 30, 2026, from 13F filings
Held by institutions
36.9%
21M of 58M shares
Institutional holders
60
22 new, 12 sold out
Net institutional buying
0M
In Q2 2026
Insider trades, 12 months
0 buys · 9 sales
Net sold $499.09K
Shares held by institutions
Holders of more than 5%
Latest Schedule 13D (active) or 13G (passive) filed by each holder
| Holder | Shares | % of class | Filing | As of |
|---|---|---|---|---|
| Gsk PLC | 9,190,606 | 16.40% | 13D (active) amendment | Mar 27, 2025 |
Top institutional holders
13F holdings as of Jun 30, 2026
| Holder | Shares | % of SPRO | Value | Change | % of portfolio |
|---|---|---|---|---|---|
| GSK plc | 9,190,606 | 15.78% | $20.31M | – | 3.37% |
| Pfizer Inc | 2,362,348 | 4.06% | $5.34M | – | 3.13% |
| Vanguard Capital Management LLC | 2,036,226 | 3.50% | $4.50M | +236,346 | 0.00% |
| Renaissance Technologies LLC | 947,904 | 1.63% | $2.09M | −241,331 | 0.00% |
| Alphabet Inc. | 889,979 | 1.53% | $1.97M | – | 0.00% |
| Susquehanna International Group, Llp | 759,290 | 1.30% | $1.68M | +426,175 | 0.00% |
| BlackRock, Inc. | 594,404 | 1.02% | $1.31M | +161,202 | 0.00% |
| Geode Capital Management, LLC | 566,329 | 0.97% | $1.25M | +46,407 | 0.00% |
| Raymond James Financial Inc | 521,705 | 0.90% | $1.15M | New | 0.00% |
| Two Sigma Investments, LP | 382,814 | 0.66% | $846.02K | −502,817 | 0.00% |
| Arrowstreet Capital, Limited Partnership | 332,970 | 0.57% | $735.86K | New | 0.00% |
| Vanguard Fiduciary Trust Co | 287,648 | 0.49% | $635.70K | +23,533 | 0.00% |
| Gsa Capital Partners Llp | 285,906 | 0.49% | $632.00K | +7,602 | 0.04% |
| Dimensional Fund Advisors LP | 274,820 | 0.47% | $607.62K | +245,052 | 0.00% |
| Goldman Sachs Group Inc | 256,985 | 0.44% | $567.94K | New | 0.00% |
| State Street Corp | 214,751 | 0.37% | $474.60K | – | 0.00% |
| Jane Street Group, LLC | 158,097 | 0.27% | $349.39K | +51,752 | 0.00% |
| UBS Group AG | 139,680 | 0.24% | $308.69K | +136,671 | 0.00% |
| Bridgeway Capital Management, LLC | 114,800 | 0.20% | $253.71K | – | 0.00% |
| Northern Trust Corp | 108,274 | 0.19% | $239.29K | −12,710 | 0.00% |
Institutional buying and selling by quarter
Positions opened, added to, reduced and closed by 13F filers
| Quarter | Holders | Shares held | % of shares | New / added | Reduced / closed | Shares bought | Shares sold |
|---|---|---|---|---|---|---|---|
| Q2 2026 | 60 | 21M | 36.9% | 22 / 17 | 6 / 12 | 3M | 3M |
| Q1 2026 | 50 | 21M | 36.2% | 8 / 13 | 10 / 13 | 3M | 1M |
| Q4 2025 | 56 | 21M | 36.3% | 16 / 14 | 12 / 6 | 11M | 2M |
| Q3 2025 | 47 | 11M | 19.4% | 14 / 13 | 6 / 11 | 2M | 1M |
| Q2 2025 | 44 | 11M | 19.0% | 16 / 9 | 9 / 10 | 2M | 6M |
| Q1 2025 | 38 | 15M | 25.9% | 1 / 8 | 11 / 12 | 0M | 1M |
| Q4 2024 | 50 | 16M | 27.6% | 12 / 13 | 9 / 8 | 5M | 1M |
| Q3 2024 | 46 | 12M | 21.2% | 6 / 5 | 12 / 7 | 1M | 2M |
| Q2 2024 | 48 | 14M | 23.8% | 5 / 12 | 8 / 11 | 1M | 1M |
| Q1 2024 | 54 | 14M | 23.7% | 11 / 12 | 12 / 7 | 2M | 2M |
| Q4 2023 | 50 | 14M | 23.8% | 6 / 11 | 10 / 8 | 2M | 0M |
| Q3 2023 | 54 | 14M | 24.4% | 5 / 12 | 14 / 7 | 1M | 1M |
Top mutual fund and ETF holders
Latest monthly portfolio reports (Form N-PORT)
21 funds held SPRO in Q2 2026, 75% of their shares through ETFs. Each fund counts once per quarter, from its quarter-end report.
| Fund | Shares | % of SPRO | Value | % of fund | As of |
|---|---|---|---|---|---|
| Vanguard Total Stock Market Index Fund | 1,395,976 | 2.40% | $3.09M | 0.00% | Jun 30, 2026 |
| Vanguard Extended Market Index Fund | 593,254 | 1.02% | $1.31M | 0.00% | Jun 30, 2026 |
| Fidelity Extended Market Index Fund | 224,070 | 0.38% | $634.12K | 0.00% | May 31, 2026 |
| iShares Micro-Cap ETF | 151,203 | 0.26% | $334.16K | 0.02% | Jun 30, 2026 |
| Fidelity Total Market Index Fund | 107,797 | 0.19% | $305.07K | 0.00% | May 31, 2026 |
| Fidelity Series Total Market Index Fund | 67,356 | 0.12% | $190.62K | 0.00% | May 31, 2026 |
| Dimensional U.S. Small Cap ETF | 65,997 | 0.11% | $77.22K | 0.00% | Jul 31, 2026 |
| Ultra-Small Company Market Fund | 64,800 | 0.11% | $143.21K | 0.10% | Jun 30, 2026 |
| Acuitas US Microcap Fund | 56,457 | 0.10% | $124.77K | 0.11% | Jun 30, 2026 |
| Omni Small-Cap Value Fund | 50,000 | 0.09% | $110.50K | 0.01% | Jun 30, 2026 |
| U.S. Micro Cap Portfolio | 46,660 | 0.08% | $54.59K | 0.00% | Jul 31, 2026 |
| Fidelity Nasdaq Composite Index Fund | 36,745 | 0.06% | $103.99K | 0.00% | May 31, 2026 |
| Invesco NASDAQ Future Gen 200 ETF | 35,591 | 0.06% | $100.72K | 0.53% | May 31, 2026 |
| Schwab Total Stock Market Index Fund | 28,565 | 0.05% | $33.42K | 0.00% | Jul 31, 2026 |
| Invesco RAFI US 1500 Small-Mid ETF | 26,957 | 0.05% | $31.54K | 0.00% | Jul 31, 2026 |
Officers, directors and major owners
People who filed Forms 3, 4 or 5 in the last two years
| Name | Role | Shares owned | % of shares | Latest filing |
|---|---|---|---|---|
| Esther Rajavelu | See Remarks, Director | 946,000 | 1.62% | Nov 10, 2026 |
| Debra Zack | Chief Medical Officer | 162,311 | 0.28% | Aug 6, 2026 |
| Timothy Keutzer | Chief Operating Officer | 742,506 | 1.28% | Feb 9, 2026 |
| Sath Shukla | CEO & President | 1,886,077 | 3.24% | Feb 5, 2025 |
| William Ho | Director | – | – | Nov 10, 2026 |
| Cynthia Smith | Director | 85,000 | 0.15% | Jun 25, 2026 |
| John C. Pottage Jr | Director | 85,000 | 0.15% | Jun 25, 2026 |
| Milind Deshpande | Director | 101,454 | 0.17% | Jun 25, 2026 |
| Frank E. Thomas | Director | 85,000 | 0.15% | Jun 25, 2026 |
| Scott Thomas Jackson | Director | 85,000 | 0.15% | Jun 25, 2026 |
| Patrick V.J.J. Vink | Director | 85,000 | 0.15% | Jun 25, 2026 |
| Kathleen Tregoning | Director | 85,000 | 0.15% | Jun 25, 2026 |
| Ankit Mahadevia | Director | 769,111 | 1.32% | Sep 3, 2025 |
Insider trades
Common stock transactions reported on Form 4, newest first
| Insider | Date | Transaction | Shares | Price | Value | Shares after |
|---|---|---|---|---|---|---|
| Esther Rajavelu See Remarks, Director | Nov 9, 2026 | Sale | −40,851 | $1.04 | $42.49K | 946,000 |
| Debra Zack Chief Medical Officer | Aug 3, 2026 | Award | +162,311 | – | – | 162,311 |
| Frank E. Thomas Director | Jun 23, 2026 | Award | +10,000 | – | – | 85,000 |
| Patrick V.J.J. Vink Director | Jun 23, 2026 | Award | +10,000 | – | – | 85,000 |
| Milind Deshpande Director | Jun 23, 2026 | Award | +10,000 | – | – | 101,454 |
| Kathleen Tregoning Director | Jun 23, 2026 | Award | +10,000 | – | – | 85,000 |
| Cynthia Smith Director | Jun 23, 2026 | Award | +10,000 | – | – | 85,000 |
| Scott Thomas Jackson Director | Jun 23, 2026 | Award | +10,000 | – | – | 85,000 |
| John C. Pottage Jr Director | Jun 23, 2026 | Award | +10,000 | – | – | 85,000 |
| Esther Rajavelu See Remarks | May 4, 2026 | Sale | −25,240 | $2.51 | $63.35K | 986,851 |
| Timothy Keutzer Chief Operating Officer | Feb 6, 2026 | Sale | −18,652 | $2.36 | $44.02K | 742,506 |
| Esther Rajavelu See Remarks | Feb 6, 2026 | Sale | −50,816 | $2.36 | $119.93K | 1,012,091 |
| Esther Rajavelu See Remarks | Feb 6, 2026 | Sale | −37,101 | $2.36 | $87.56K | 1,062,907 |
| Timothy Keutzer Chief Operating Officer | Feb 4, 2026 | Sale | −3,471 | $2.24 | $7.78K | 761,158 |
| Timothy Keutzer Chief Operating Officer | Feb 3, 2026 | Sale | −24,224 | $2.14 | $51.84K | 764,629 |
| Timothy Keutzer Chief Operating Officer | Feb 2, 2026 | Award | +68,000 | – | – | 807,744 |
| Timothy Keutzer Chief Operating Officer | Feb 2, 2026 | Sale | −18,891 | $2.20 | $41.56K | 788,853 |
| Esther Rajavelu See Remarks | Feb 2, 2026 | Award | +249,000 | – | – | 1,118,450 |
| Esther Rajavelu See Remarks | Feb 2, 2026 | Sale | −18,442 | $2.20 | $40.57K | 1,100,008 |
| Esther Rajavelu See Remarks | Nov 7, 2025 | Sale | −40,270 | $2.37 | $95.44K | 869,450 |
| Timothy Keutzer Chief Operating Officer | Aug 28, 2025 | Sale | −1,695 | $1.97 | $3.34K | 739,744 |
| Ankit Mahadevia Director | Aug 28, 2025 | Sale | −6,572 | $1.97 | $12.95K | 703,294 |
| John C. Pottage Jr Director | Jun 12, 2025 | Award | +20,000 | – | – | 75,000 |
| Kathleen Tregoning Director | Jun 12, 2025 | Award | +20,000 | – | – | 75,000 |
| Cynthia Smith Director | Jun 12, 2025 | Award | +20,000 | – | – | 75,000 |
| Scott Thomas Jackson Director | Jun 12, 2025 | Award | +20,000 | – | – | 75,000 |
| Ankit Mahadevia Director | Jun 12, 2025 | Award | +20,000 | – | – | 709,866 |
| Frank E. Thomas Director | Jun 12, 2025 | Award | +20,000 | – | – | 75,000 |
| Milind Deshpande Director | Jun 12, 2025 | Award | +20,000 | – | – | 91,454 |
| Patrick V.J.J. Vink Director | Jun 12, 2025 | Award | +20,000 | – | – | 75,000 |
| Esther Rajavelu See Remarks | May 2, 2025 | Award | +185,000 | – | – | 909,720 |
| Sath Shukla CEO & President | Feb 5, 2025 | Sale | −6,139 | $0.78 | $4.79K | 1,886,077 |
| Sath Shukla CEO & President | Feb 5, 2025 | Sale | −42,786 | $0.78 | $33.37K | 1,843,291 |
| Sath Shukla CEO & President | Feb 5, 2025 | Sale | −106,408 | $0.78 | $83.00K | 1,736,883 |
| Esther Rajavelu CFO & CBO | Feb 5, 2025 | Sale | −20,689 | $0.78 | $16.14K | 724,720 |
| Ankit Mahadevia Director | Feb 5, 2025 | Sale | −55,260 | $0.78 | $43.10K | 689,866 |
| Ankit Mahadevia Director | Feb 5, 2025 | Sale | −13,959 | $0.78 | $10.89K | 745,126 |
| Timothy Keutzer Chief Operating Officer | Feb 5, 2025 | Sale | −3,974 | $0.78 | $3.10K | 794,002 |
| Timothy Keutzer Chief Operating Officer | Feb 5, 2025 | Sale | −27,643 | $0.78 | $21.56K | 766,359 |
| Timothy Keutzer Chief Operating Officer | Feb 5, 2025 | Sale | −24,920 | $0.78 | $19.44K | 741,439 |
| Sath Shukla CEO & President | Feb 3, 2025 | Award | +751,407 | – | – | 1,892,216 |
| Esther Rajavelu CFO & CBO | Feb 3, 2025 | Award | +266,139 | – | – | 645,409 |
| Esther Rajavelu CFO & CBO | Feb 3, 2025 | Award | +100,000 | – | – | 745,409 |
| Timothy Keutzer Chief Operating Officer | Feb 3, 2025 | Award | +266,139 | – | – | 797,976 |
| Esther Rajavelu CFO & CBO | Nov 8, 2024 | Sale | −17,245 | $1.30 | $22.42K | 379,270 |
| Esther Rajavelu CFO & CBO | Nov 7, 2024 | Sale | −23,351 | $1.31 | $30.59K | 396,515 |
| Ankit Mahadevia Director | Aug 27, 2024 | Sale | −5,912 | $1.35 | $7.98K | 759,085 |
| Timothy Keutzer Chief Operating Officer | Aug 27, 2024 | Sale | −2,213 | $1.35 | $2.99K | 531,837 |
| Sath Shukla CEO & President | Aug 27, 2024 | Sale | −2,757 | $1.35 | $3.72K | 1,140,809 |
| Sath Shukla CEO and President | Aug 5, 2024 | Sale | −17,641 | $1.31 | $23.11K | 1,143,566 |
| Sath Shukla CEO and President | Aug 2, 2024 | Sale | −14,800 | $1.32 | $19.54K | 1,161,207 |
| Kathleen Tregoning Director | May 29, 2024 | Award | +20,000 | – | – | 55,000 |
| Cynthia Smith Director | May 29, 2024 | Award | +20,000 | – | – | 55,000 |
| Scott Thomas Jackson Director | May 29, 2024 | Award | +20,000 | – | – | 55,000 |
| John C. Pottage Jr Director | May 29, 2024 | Award | +20,000 | – | – | 55,000 |
| Frank E. Thomas Director | May 29, 2024 | Award | +20,000 | – | – | 55,000 |
| Ankit Mahadevia Director | May 29, 2024 | Award | +20,000 | – | – | 764,997 |
| Milind Deshpande Director | May 29, 2024 | Award | +20,000 | – | – | 71,454 |
| Patrick V.J.J. Vink Director | May 29, 2024 | Award | +20,000 | – | – | 55,000 |
| Sath Shukla CEO and President, Director | Feb 5, 2024 | Sale(10b5-1 plan) | −45,093 | $1.45 | $65.38K | 1,176,007 |
Awards, option exercises, tax withholding and gifts are shown alongside open-market buys and sales. Each name links to the filing on SEC EDGAR.
Short interest
Shares sold short and not yet bought back, as of Oct 30, 2026 (FINRA, reported twice a month)
Short % of float
1.79%
1M shares short
Days to cover
2.2
At 0M shares a day
Change since last report
-6.4%
From 1M shares
Short volume, 20 days
40.7%
Of volume reported to FINRA
Shares sold short, last 12 months
Short sale volume counts trades marked short on any given day, including market-maker hedging, so it runs far higher than the share of Spero Therapeutics's stock actually held short. Settlement fails (shares not delivered on time) peaked at 50,000 shares on Oct 2, 2026 over the last 90 days.
Planned insider sales
Notices of proposed sale filed on Form 144 before shares are sold
| Seller | Filed | Shares | Market value | Planned sale | Acquired through |
|---|---|---|---|---|---|
| Satyavrat Shukla Officer, Director | Feb 5, 2024 | 45,093 | $65.47K | Feb 5, 2024 | Restricted Stock |
| Satyavrat Shukla Officer | Aug 29, 2023 | 4,163 | $5.41K | Aug 29, 2023 | Restricted Stock |
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