Spero Therapeutics
SPRO · NASDAQ
$1.22+$0.10 (+8.93%)TodayMarket closed ·
Prev close $1.12
Who owns SPRO
Largest institutional holders, from their latest 13F filings
The 10 largest institutions hold 31.6% of SPRO’s shares.
- GSK plc15.9%
- Pfizer Inc.4.1%
- Vanguard Capital Management, LLC3.5%
- Renaissance Technologies LLC1.6%
- Next 6 largest institutions6.5%
- All other shareholders68.4%
| Holder | Shares | % of shares |
|---|---|---|
| GSK plc | 9.19M | 15.87% |
| Pfizer Inc. | 2.36M | 4.08% |
| Vanguard Capital Management, LLC | 2.04M | 3.52% |
| Renaissance Technologies LLC | 947.90K | 1.64% |
| Alphabet, Inc. | 889.98K | 1.54% |
| Susquehanna International Group, LLP | 759.29K | 1.31% |
| BlackRock Institutional Trust Company, N.A. | 583.21K | 1.01% |
| Geode Capital Management, L.L.C. | 566.33K | 0.98% |
| ClariVest Asset Management LLC | 518.64K | 0.90% |
| Florida State Board of Administration | 462.19K | 0.80% |
Largest mutual fund holders
| Holder | Shares | % of shares |
|---|---|---|
| Vanguard Total Stock Market Index Fund | 1.40M | 2.41% |
| Vanguard Extended Market Index Fund | 593.25K | 1.02% |
| Florida State Board Administration Fund | 462.19K | 0.80% |
| Fidelity Extended Market Index Fund | 248.94K | 0.43% |
| iShares Micro-Cap ETF | 153.19K | 0.26% |
Insider trades
Form 4 filings by officers, directors and large holders
Over the last 6 months, insiders sold $63.35K (1 trade) of SPRO on the open market, with no buys.
| Insider | Type | Shares | Value |
|---|---|---|---|
| Zack Debra | Award | 324.68K | — |
| Zack Debra | Award | 162.31K | — |
| Tregoning Kathleen | Award | 20.00K | — |
| Tregoning Kathleen | Award | 10.00K | — |
| Smith Cynthia | Award | 20.00K | — |
| Smith Cynthia | Award | 10.00K | — |
| Jackson Scott Thomas | Award | 20.00K | — |
| Jackson Scott Thomas | Award | 10.00K | — |
| VINK PATRICK V.J.J. | Award | 20.00K | — |
| VINK PATRICK V.J.J. | Award | 10.00K | — |
Short interest
Settled Sep 30, 2026
- Shares short
- 794.51K
- Days to cover
- 1.00
- % of shares outstanding
- 1.37%
- Average daily volume
- 1.14M
- Change since last report
- −18.6%
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