Prothena (PRTA)
Develops investigational protein-dysregulation therapies with a partner-heavy clinical pipeline.
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Develops investigational therapies for diseases caused by protein dysregulation, with clinical programs spanning Parkinson's disease, ATTR amyloidosis, Alzheimer's disease, and broader neurodegeneration. Revenue and late-stage progress depend heavily on collaboration partners after birtamimab was discontinued and the workforce was reduced.
Develops investigational therapies for diseases caused by protein dysregulation, using an Elan/Athena antibody-discovery lineage. Current named programs include prasinezumab for Parkinson's disease, coramitug for ATTR amyloidosis, BMS-986446 for Alzheimer's disease, PRX019 for neurodegeneration, TDP-43 CYTOPE for ALS, and PRX012-TfR for Alzheimer's disease.
Operates from an Irish public-company base with Nasdaq-listed ordinary shares and one research-and-development segment rather than commercial product lines. Revenue is collaboration-driven, with Roche, Novo Nordisk, and Bristol Myers Squibb controlling or co-developing the most advanced clinical assets.
Execution now centers on supporting partnered trials, rebuilding wholly owned preclinical programs, and managing a smaller organization after birtamimab was discontinued. The business depends on trial outcomes, partner advancement decisions, milestone receipts, and regulatory approvals for investigational drugs.
Company facts
Target rangeAs of Sep 21, 2026
Latest analyst notes
| Date | Firm | Action | Prior | Current |
|---|---|---|---|---|
| Jul 24, 2026 | H.C. Wainwright | Reiterate | Rating: —Target: $20 | Target: $30 |
| Mar 13, 2026 | Stifel Nicolaus | Target | Target: — | Target: $19 |
| Dec 1, 2025 | JMP Securities | Target | Target: $11 | Target: $19 |
| Dec 1, 2025 | Deutsche Bank | Target | Target: — | Target: $19 |
| Oct 28, 2025 | Piper Sandler | Reiterate | Rating: —Target: — | Target: $36 |
EPSReportedEstimate
RevenueReportedEstimate
Balance sheet, Jun 30, 2026Cash & short-term investments $288.2M · Total debt $7.0M · Total assets $302.6M · Shareholders' equity $286.9M
- Revenue
- $1.0M
- Operating income
- −$21.1M
- Net income
- −$18.6M
No dividends on record.
| Institutions | 92.75% | 47.62M shares | |
|---|---|---|---|
| 197 holders · as of Jun 30, 2026 | |||
| Insiders | 20.43% | 10.49M shares | |
| 11 holders · as of Sep 21, 2026 | |||
| Strategic holders | 10.33% | 5.30M shares | |
| 1 holder · as of May 6, 2025 | |||
| Adds to | 123.51% | ||
51.34M company shares as of Sep 22, 2026 · institutions as of Jun 30, 2026 · holders as of their latest filing
These groups come from separate filings that can overlap, so they add to 123.51%; nothing is left for Other.
Top shareholders13F · 13D/G · Form 4
| Holder | Stake | Shares | Date |
|---|---|---|---|
FMR LLCInstitution | 14.02% | 7.20M | as of Jun 30, 2026 |
William P. Scully1Insider10 percent owner | 10.86% | 5.38M | filed Sep 21, 2026 |
EcoR1 Capital, LLCStrategic10 percent owner | 10.33% | 5.30M | filed May 6, 2025 |
Rubric Capital Management LPInstitution | 9.74% | 5.00M | as of Jun 30, 2026 |
BlackRock, Inc.Institution | 9.48% | 4.87M | as of Jun 30, 2026 |
- William P. Scully's transaction reports restate only vehicles that traded; the 2026 ownership statement (5.38M) plus the 194.5K net shares acquired since is used instead.
Insider tradesForm 4
| Date | Insider | Role | Shares | Avg price |
|---|---|---|---|---|
| Sep 18, 2026 | William P. Scully | 10 percent owner | +100,000 | $8.43 |
| Sep 2, 2026 | William P. Scully | 10 percent owner | +27,000 | $9.47 |
| Aug 20, 2026 | William P. Scully | 10 percent owner | +50,000 | $8.79 |
| Aug 7, 2026 | William P. Scully | 10 percent owner | +37,500 | $8.62 |
| Jul 29, 2026 | Michael John Isaacs | officer: General Counsel & Company Sec. | −8,386 | $8.47 |
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Compare
| Company | Price | Change | |||||
|---|---|---|---|---|---|---|---|
| Prothena | $8.93 | +4.94% | $445.5M | — | — | 8.2 | −77.2% |
| Pfizer | $27.82 | +0.29% | $158.10B | 36.7 | 9.9 | 2.5 | +2.6% |
| Alnylam Pharmaceuticals | $253.72 | +3.85% | $32.69B | 41.3 | 30.1 | 6.8 | +66.9% |
| BridgeBio Pharma | $69.28 | +4.06% | $13.04B | — | — | 18.8 | +120.4% |
| Eli Lilly | $1,169.03 | +0.36% | $1.10T | 39.1 | 28.6 | 13.8 | +47.7% |
| Biogen | $224.42 | +2.44% | $32.37B | 38.8 | 16.9 | 3.3 | +3.4% |
| AC Immune | $2.72 | +2.26% | $270.2M | — | — | 12.6 | +823.6% |
| Ionis Pharmaceuticals | $45.50 | +1.33% | $7.46B | — | — | 8.5 | −40.7% |
| Denali Therapeutics | $21.44 | +4.74% | $3.25B | — | — | 901.4 | — |
| Median | 38.9 | 22.8 | 10.6 | +47.7% |