Prothena Corporation plc
- Open
- 9.74
- Day high
- 10.00
- Day low
- 9.55
- Prev close
- 9.79
- Volume
- 194K
- Mkt cap
- $504M
- P/E (TTM)
- —
- EPS (TTM)
- —
- P/B
- 1.6
- P/S
- 8.7
- Yield
- —
- Per share
- —
- ▲Insiders net buying $3.1M over the last 3 months (5 open-market buys, 0 sales)
- 🏛Institutions mixed (13F)
Prothena Corporation plc (PRTA) is a Healthcare company listed on NASDAQ. The stock is up 56% over the past year. Over the trailing 3 months, insiders filed 5 open-market buys and 0 sales (SEC Form 4).
Prothena Corporation plc (PRTA) financials & analyst ratings
Fundamentals (TTM)
Analyst consensus · 2 analysts
Source: exchange market data + company filings. Figures are trailing-twelve-month or as most recently reported. For informational purposes only — not investment advice.
PRTA earnings date, history & EPS estimates
| Report date | EPS est | EPS actual | Surprise | Revenue | Rev. surprise |
|---|---|---|---|---|---|
| May 7, 2026 | $-0.31 | $0.52 | +267.7% | $51M | +6215.2% |
| Feb 19, 2026 | $-0.45 | $-0.44 | +2.2% | $21000 | -98.4% |
| Nov 6, 2025 | $-0.60 | $-0.67 | -11.7% | $2M | +262.2% |
| May 8, 2025 | $-0.92 | $-1.12 | -21.7% | $3M | -81.6% |
| Feb 20, 2025 | $-1.02 | $-1.08 | -5.9% | $2M | -71.8% |
| Aug 8, 2024 | $-1.05 | $1.22 | +216.2% | $132M | +1130.3% |
| Feb 15, 2024 | $-1.23 | $-1.26 | -2.4% | $316000 | -85.3% |
| Nov 2, 2023 | $-0.32 | $0.38 | +218.8% | $85M | +103.6% |
| Aug 3, 2023 | $-0.92 | $-1.03 | -12.0% | $4M | -11.1% |
| May 4, 2023 | $-0.83 | $-0.89 | -7.2% | $2M | -52.0% |
| Feb 23, 2023 | $-0.47 | $0.12 | +125.5% | $50M | +577.4% |
| Nov 3, 2022 | $-0.31 | $-0.97 | -212.9% | $2M | -94.0% |
PRTA insider trading activity (SEC Form 4)
| Date | Insider | Type | Shares | Price |
|---|---|---|---|---|
| Jun 18, 2026 | SCULLY WILLIAM P10 percent owner | Buy | 20,000 | $7.90 |
| Jun 12, 2026 | SCULLY WILLIAM P10 percent owner | Buy | 125,000 | $8.17 |
| Jun 5, 2026 | SCULLY WILLIAM P10 percent owner | Buy | 50,000 | $9.31 |
| Jun 3, 2026 | SCULLY WILLIAM P10 percent owner | Buy | 50,000 | $9.43 |
| May 26, 2026 | SCULLY WILLIAM P10 percent owner | Buy | 100,000 | $9.81 |
| May 15, 2026 | Dunn William H. Jr.director | Grant | 27,000 | $9.76 |
| May 15, 2026 | Ekman Larsdirector | Grant | 27,000 | $9.76 |
| May 15, 2026 | COLLIER RICHARD Tdirector | Grant | 27,000 | $9.76 |
| May 15, 2026 | Selkoe Dennis J.director | Grant | 27,000 | $9.76 |
| May 15, 2026 | WELCH DANIEL Gdirector | Grant | 27,000 | $9.76 |
| May 15, 2026 | Cooke Shanedirector | Grant | 27,000 | $9.76 |
| Apr 10, 2026 | Kingston Anne Evansofficer: Chief Strategy Officer | Grant | 100,000 | $10.50 |
| Mar 5, 2026 | Smith Brandon S.officer: Chief Operating Officer | Grant | 190,000 | $9.36 |
| Mar 5, 2026 | Nguyen Tranofficer: Chief Strategy Officer and CFO | Grant | 230,000 | $9.36 |
| Mar 5, 2026 | Walker Karin Lofficer: Chief Accounting Officer | Grant | 150,000 | $9.36 |
Source: PRTA SEC Form 4 filings, latest Jun 18, 2026. For informational purposes only — not investment advice.
See the full PRTA insider & 13F page →Prothena Corporation plc company profile
Overview
Prothena Corporation plc (NASDAQ:PRTA) is a late-stage clinical biotechnology company founded in 2012 and headquartered in Dublin, Ireland. The company emerged as a spinoff focused on developing novel protein-based therapies for life-threatening neurodegenerative and rare diseases. Since its founding, Prothena has built a robust pipeline of investigational treatments targeting protein misfolding disorders, including Alzheimer's disease, Parkinson's disease, and various forms of amyloidosis. The company operates through strategic partnerships with major pharmaceutical companies including Roche, Bristol-Myers Squibb, and Novo Nordisk, while maintaining wholly-owned programs that could position it for independent commercialization.
Business
Prothena operates in the biotechnology sector, specifically focusing on protein dysregulation diseases - conditions where proteins misfold and accumulate in tissues, causing cellular damage and organ dysfunction. These diseases include neurodegenerative disorders like Alzheimer's and Parkinson's disease, as well as rare conditions called amyloidoses where abnormal protein deposits damage organs. The company's approach centers on developing monoclonal antibodies - laboratory-engineered proteins that can precisely target and neutralize disease-causing proteins in the body. Think of these as highly specific molecular guided missiles that seek out and bind to harmful protein aggregates, potentially clearing them from tissues or preventing their formation. Prothena's portfolio consists of multiple business segments: 1. Wholly-owned programs (approximately 50% of pipeline focus): These include Birtamimab for AL amyloidosis, PRX012 for Alzheimer's disease, PRX005 for Alzheimer's disease, and PRX123 (a dual vaccine approach for Alzheimer's). The company retains full commercial rights and potential profits from these programs. 2. Partnered programs (approximately 50% of pipeline focus): These involve collaborations where Prothena provides the initial research and development while partners like Roche (Prasinezumab for Parkinson's), Novo Nordisk (Coramitug for heart-related amyloidosis), and Bristol-Myers Squibb (BMS-986446 for Alzheimer's) handle later-stage development and commercialization in exchange for milestone payments and royalties. The company's lead program, Birtamimab, targets AL amyloidosis, a rare blood cancer where abnormal antibody proteins accumulate in organs, often proving fatal within months. This represents Prothena's nearest-term commercial opportunity, with Phase 3 trial results expected in 2025.
Revenue model
Prothena operates a dual revenue model typical of clinical-stage biotechnology companies. The company currently generates minimal product revenue, instead relying on partnership agreements and milestone payments from pharmaceutical collaborators. The primary revenue streams include: 1) Upfront licensing fees when signing partnership deals, 2) Development milestone payments as programs advance through clinical trials (ranging from $10-80 million per milestone), 3) Regulatory milestone payments upon drug approvals, and 4) Future royalties on commercial sales of partnered products. For example, the company received $80 million from Bristol-Myers Squibb in 2024 for licensing PRX019. For wholly-owned programs like Birtamimab, Prothena plans to commercialize independently, generating revenue through direct product sales to hospitals and specialty clinics. The target market for AL amyloidosis treatment involves approximately 5,000 Mayo Stage IV patients in the U.S., treated by a concentrated network of hematologists and amyloidosis specialists. Several factors could significantly impact margins: Clinical trial success rates directly affect partnership value and milestone payments. Regulatory approval timelines influence when revenue generation begins. Manufacturing costs for complex biologics can be substantial, though Prothena's subcutaneous delivery approach may offer cost advantages over intravenous competitors. Competition from other amyloid-targeting therapies could pressure pricing, while reimbursement policies from Medicare and private insurers will largely determine commercial viability. The company's cash burn rate of approximately $150-175 million annually creates pressure to achieve clinical milestones and secure additional partnerships or financing.
Competitive moat
Prothena's competitive moat appears moderate but narrowing in most therapeutic areas. In Alzheimer's disease, the company faces intense competition from approved treatments like Aduhelm and Leqembi, as well as numerous pipeline candidates from major pharmaceutical companies. Prothena's potential advantages include its subcutaneous delivery method (monthly injections versus bi-weekly infusions) and targeting of multiple toxic amyloid forms, but these represent incremental rather than revolutionary improvements. The company's strongest moat exists in AL amyloidosis, where Birtamimab could become the first anti-amyloid therapy demonstrating early survival benefit in Mayo Stage IV patients. This rare disease indication has limited competition and high unmet medical need, potentially providing several years of market exclusivity even beyond patent protection. The concentrated prescriber base and specialized treatment centers create natural barriers to entry. However, this moat faces several vulnerabilities: Large pharmaceutical companies with superior resources could develop competing therapies more rapidly. Patent expirations will eventually eliminate exclusivity periods. Most critically, clinical trial failures could eliminate competitive advantages entirely - a single failed Phase 3 trial could destroy years of development work and partnerships. The partnership strategy provides some protection by diversifying risk across multiple programs and leveraging partners' commercial capabilities, but also means Prothena captures only a fraction of successful programs' value. Overall, the company operates in a high-risk, high-reward environment where scientific execution and regulatory success determine competitive positioning more than sustainable business model advantages.
Risks & safety
Prothena presents a moderate margin of safety for a clinical-stage biotechnology company, though significant risks remain inherent to the business model. • Strong liquidity position: $472 million cash as of December 2024, providing approximately 2.5-3 years of runway at current burn rates of $168-175 million annually • Minimal debt burden: Debt-to-equity ratio of only 2.2%, indicating very low financial leverage and solvency risk • Excellent current ratio: 10.0x current ratio demonstrates strong short-term liquidity to meet obligations • Valuation metrics mixed: Trading at 1.5x book value appears reasonable for a company with substantial cash holdings, though negative earnings make traditional P/E ratios meaningless • Graham net-net value: Stock trades below net current asset value, suggesting potential downside protection from liquidation value • Binary clinical risks: Primary safety concern involves upcoming Phase 3 Birtamimab results in Q2 2025 - failure could eliminate the company's lead commercial opportunity and trigger significant stock decline • Partnership dependency: Revenue concentration in milestone payments creates lumpy, unpredictable cash flows • Regulatory uncertainty: FDA approval processes for novel biologics carry inherent execution risks beyond management control
Recent development
Over the past few years, Prothena has executed a strategic transformation from a research-focused company to a late-stage clinical organization preparing for potential commercialization. The company significantly expanded its Alzheimer's disease portfolio, advancing three distinct approaches: PRX012 (anti-amyloid antibody), PRX005 (anti-tau antibody), and PRX123 (dual vaccine targeting both amyloid and tau proteins). This diversified approach hedges against the possibility that single-target therapies may prove insufficient for Alzheimer's treatment. The company has also strengthened its partnership strategy, securing major collaborations that provide both financial resources and validation. The $80 million Bristol-Myers Squibb deal for PRX019 in 2024 exemplifies this approach, while ongoing partnerships with Roche and Novo Nordisk advance additional programs through Phase 2 trials. These partnerships allow Prothena to maintain a broader pipeline than its resources would otherwise permit. Perhaps most significantly, Prothena is preparing for independent commercialization of Birtamimab, its lead AL amyloidosis treatment. The company has begun building commercial infrastructure and market access capabilities, targeting the concentrated network of approximately 200 treatment centers in the U.S. This represents a major strategic shift from purely partnered development to potential direct market participation. Recent clinical advances include Fast Track designation for PRX123 from the FDA, indicating regulatory recognition of the program's potential importance. The company has also optimized its development approach, designing PRX012 for once-monthly subcutaneous administration to improve patient convenience compared to existing bi-weekly intravenous Alzheimer's treatments.
PRTA company profile · for informational purposes only — not investment advice.
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