Spero Therapeutics, Inc.
SPRO · Pharmaceutical Preparations · 57.9M shares · +20%/yr ↑ dilution · EDGAR filings ↗
Reference price $2.51 · est. market cap ~$145M — last insider sale, 2026-05-04 (estimated from the dated SEC Form 4 price × shares outstanding — not a live quote)
Grade
B78Clinical-stage biotech materially de-risked by a positive, statistically significant Phase 3 readout and partnered NDA now under FDA review.
Strengths
- PIVOT-PO Phase 3 met primary endpoint and stopped early for efficacy; NDA accepted with PDUFA set 6/18/2026 — major de-risking event
- GSK partnership with milestone/royalty stream ($25M received Feb 2026); cash funds operations into 2028 (current ratio 7.6)
Risks
- Single-asset dependency on tebipenem HBr and FDA approval outcome
- No product revenue base; lumpy milestone-driven economics (revenue -99% YoY)
Notable findings
- Exec changeRecent 8-K item 5.02 8-K ↗
- Fund exitedNotable fund(s) exited this quarter: VANGUARD GROUP INC
- Chronic dilutionShare count +20%/yr over 3y (dilution, book value/share -56%)
- Revenue declineRevenue -99.4% YoY
- Notable holderHeld by 3 notable fund(s): RENAISSANCE TECHNOLOGIES LLC, CITADEL ADVISORS LLC, STATE STREET CORP (as of 2026-03-31)
- Insider sellingInsider selling — 8 open-market sale(s) by 2 insider(s) (cluster of 2 insiders, ~$456,602, last 6mo) Form 4 ↗
Quarterly revenue
Last 4 quarters · from SEC filings.
Key metrics
Operating margin
9.5%
Net margin
12.8%
Return on equity
14.5%
Return on assets
12.4%
Revenue growth (QoQ)
-99.4%
Current ratio
7.6×
EBITDA
$6M
Tangible book value
$59M
Cash & investments
$40M
Stock comp / revenue
6.5%
Insider transactions · last 18 months
| Date | Insider | Type | Shares | Price |
|---|---|---|---|---|
| 2026-06-23 | Smith Cynthia | Grant | 10K | — |
| 2026-06-23 | VINK PATRICK V.J.J. | Grant | 10K | — |
| 2026-06-23 | Tregoning Kathleen | Grant | 10K | — |
| 2026-06-23 | THOMAS FRANK E | Grant | 10K | — |
| 2026-06-23 | Jackson Scott Thomas | Grant | 10K | — |
| 2026-06-23 | Pottage John C Jr | Grant | 10K | — |
| 2026-06-23 | Deshpande Milind | Grant | 10K | — |
| 2026-05-04 | Rajavelu Esther | Sell | 25K | $2.51 |
| 2026-02-06 | Keutzer Timothy | Sell | 19K | $2.36 |
| 2026-02-06 | Rajavelu Esther | Sell | 37K | $2.36 |
| 2026-02-06 | Rajavelu Esther | Sell | 51K | $2.36 |
| 2026-02-04 | Keutzer Timothy | Sell | 3.5K | $2.24 |
| 2026-02-03 | Keutzer Timothy | Sell | 24K | $2.14 |
| 2026-02-02 | Rajavelu Esther | Grant | 249K | — |
| 2026-02-02 | Rajavelu Esther | Sell | 18K | $2.20 |
| 2026-02-02 | Keutzer Timothy | Grant | 68K | — |
| 2026-02-02 | Keutzer Timothy | Sell | 19K | $2.20 |
| 2025-11-07 | Rajavelu Esther | Sell | 40K | $2.37 |
| 2025-08-28 | Mahadevia Ankit | Sell | 6.6K | $1.97 |
| 2025-08-28 | Keutzer Timothy | Sell | 1.7K | $1.97 |
| 2025-06-12 | THOMAS FRANK E | Grant | 20K | — |
| 2025-06-12 | Mahadevia Ankit | Grant | 20K | — |
| 2025-06-12 | Deshpande Milind | Grant | 20K | — |
| 2025-06-12 | Jackson Scott Thomas | Grant | 20K | — |
| 2025-06-12 | VINK PATRICK V.J.J. | Grant | 20K | — |
| 2025-06-12 | Pottage John C Jr | Grant | 20K | — |
| 2025-06-12 | Smith Cynthia | Grant | 20K | — |
| 2025-06-12 | Tregoning Kathleen | Grant | 20K | — |
| 2025-05-02 | Rajavelu Esther | Grant | 185K | — |
| 2025-02-05 | Keutzer Timothy | Sell | 4.0K | $0.78 |
| 2025-02-05 | Keutzer Timothy | Sell | 28K | $0.78 |
| 2025-02-05 | Keutzer Timothy | Sell | 25K | $0.78 |
| 2025-02-05 | Mahadevia Ankit | Sell | 55K | $0.78 |
| 2025-02-05 | Shukla Sath | Sell | 6.1K | $0.78 |
| 2025-02-05 | Shukla Sath | Sell | 43K | $0.78 |
| 2025-02-05 | Shukla Sath | Sell | 106K | $0.78 |
| 2025-02-05 | Mahadevia Ankit | Sell | 14K | $0.78 |
| 2025-02-05 | Rajavelu Esther | Sell | 21K | $0.78 |
| 2025-02-03 | Rajavelu Esther | Grant | 266K | — |
| 2025-02-03 | Rajavelu Esther | Grant | 100K | — |
| 2025-02-03 | Keutzer Timothy | Grant | 266K | — |
| 2025-02-03 | Shukla Sath | Grant | 751K | — |
All non-derivative Form 4 activity (SEC), newest first.
Notable events (8-K)
| Date | Items | |
|---|---|---|
| 2026-06-25 | Exec/director change5.03Shareholder voteExhibits | filing ↗ |
| 2026-06-22 | Reg FDOtherExhibits | filing ↗ |
| 2026-05-13 | ResultsExhibits | filing ↗ |
| 2026-03-26 | ResultsExhibits | filing ↗ |
| 2026-01-30 | Exec/director changeOther | filing ↗ |
| 2025-12-19 | OtherExhibits | filing ↗ |
| 2025-11-13 | ResultsReg FDExhibits | filing ↗ |
| 2025-08-12 | ResultsReg FDExhibits | filing ↗ |
Recent filings
| Form | Filed | Period | Accession |
|---|---|---|---|
| 8-K | 2026-06-25 | 2026-06-23 | 0001193125-26-283033 ↗ |
| 8-K | 2026-06-22 | 2026-06-17 | 0001193125-26-277506 ↗ |
| 10-Q | 2026-05-13 | 2026-03-31 | 0001193125-26-221591 ↗ |
| 8-K | 2026-05-13 | 2026-05-13 | 0001193125-26-221567 ↗ |
| 8-K | 2026-03-26 | 2026-03-26 | 0001193125-26-126244 ↗ |
| 10-K | 2026-03-26 | 2025-12-31 | 0001193125-26-126192 ↗ |
| 8-K | 2026-01-30 | 2026-01-30 | 0001193125-26-032004 ↗ |
| 8-K | 2025-12-19 | 2025-12-19 | 0001193125-25-325821 ↗ |
| 10-Q | 2025-11-13 | 2025-09-30 | 0001193125-25-280174 ↗ |
| 8-K | 2025-11-13 | 2025-11-13 | 0001193125-25-280518 ↗ |
| 8-K | 2025-08-12 | 2025-08-12 | 0001193125-25-178970 ↗ |
| 10-Q | 2025-08-12 | 2025-06-30 | 0000950170-25-107388 ↗ |