Prothena (PRTA)
Market Price (8/13/2026): $9.255 | Market Cap: $482.6 MilSector: Health Care | Industry: Biotechnology
Prothena (PRTA)
Market Price (8/13/2026): $9.255Market Cap: $482.6 MilSector: Health CareIndustry: Biotechnology
Investment Highlights Why It Matters Detailed financial logic regarding cash flow yields vs trend-riding momentum.
Cash is significant % of market capNet D/ENet Debt/Equity. Debt net of cash. Negative indicates net cash. Equity is taken as the Market Capitalization is -58% Strong revenue growthRev Chg LTMRevenue Change % Last Twelve Months (LTM) is 427% Low stock price volatilityVol 12M is 48% Megatrend and thematic driversMegatrends include Precision Medicine, and Aging Population & Chronic Disease. Themes include Targeted Therapies, Biopharmaceutical R&D, Show more. | Weak multi-year price returns2Y Excs Rtn is -101%, 3Y Excs Rtn is -157% Meaningful short interestShort Interest Days-to-CoverDTC = (Short Interest Share Quantity) / (Average Daily Trading Volume). Reflects how many days it would take to cover (close out) the short interest based on average volumes. High DTC can signify an increased risk of a short squeeze. is 13.96, Short Interest % of Basic SharesShort Interest % of Basic Shares = (Short Interest Quantity) / (Basic Shares Outstanding). A high fraction of short interest can indicate potential risk of a short squeeze. is 16% | Not profitable at operating income levelOp Inc LTMOperating Income, Last Twelve Months is -60 Mil, Op Mgn LTMOperating Margin = Operating Income / Revenue Reflects profitability before taxes and before impact of capital structure (interest payments). is -110% Weak revenue growthRev Chg QQuarterly Revenue Change % is -77% Significant share based compensationSBC/Rev LTMShare Based Compensation / Revenue (Sales), Last Twelve Months (LTM) is 53% Not cash flow generativeCFO/Rev LTMCash Flow from Operations / Revenue (Sales), Last Twelve Months (LTM) is -110%, FCF/Rev LTMFree Cash Flow / Revenue (Sales), Last Twelve Months (LTM) is -110% Yield minus risk free rate is negativeERPEquity Risk Premium (ERP) = Total Yield - Risk Free Rate, Reflects the premium above risk free assets offered by the investment. is -13% Key risksPRTA key risks include [1] a heavy dependence on its narrowed pipeline of high-risk neurodegenerative candidates following the Phase 3 failure of its former lead candidate, Show more. |
| Cash is significant % of market capNet D/ENet Debt/Equity. Debt net of cash. Negative indicates net cash. Equity is taken as the Market Capitalization is -58% |
| Strong revenue growthRev Chg LTMRevenue Change % Last Twelve Months (LTM) is 427% |
| Low stock price volatilityVol 12M is 48% |
| Megatrend and thematic driversMegatrends include Precision Medicine, and Aging Population & Chronic Disease. Themes include Targeted Therapies, Biopharmaceutical R&D, Show more. |
| Weak multi-year price returns2Y Excs Rtn is -101%, 3Y Excs Rtn is -157% |
| Meaningful short interestShort Interest Days-to-CoverDTC = (Short Interest Share Quantity) / (Average Daily Trading Volume). Reflects how many days it would take to cover (close out) the short interest based on average volumes. High DTC can signify an increased risk of a short squeeze. is 13.96, Short Interest % of Basic SharesShort Interest % of Basic Shares = (Short Interest Quantity) / (Basic Shares Outstanding). A high fraction of short interest can indicate potential risk of a short squeeze. is 16% |
| Not profitable at operating income levelOp Inc LTMOperating Income, Last Twelve Months is -60 Mil, Op Mgn LTMOperating Margin = Operating Income / Revenue Reflects profitability before taxes and before impact of capital structure (interest payments). is -110% |
| Weak revenue growthRev Chg QQuarterly Revenue Change % is -77% |
| Significant share based compensationSBC/Rev LTMShare Based Compensation / Revenue (Sales), Last Twelve Months (LTM) is 53% |
| Not cash flow generativeCFO/Rev LTMCash Flow from Operations / Revenue (Sales), Last Twelve Months (LTM) is -110%, FCF/Rev LTMFree Cash Flow / Revenue (Sales), Last Twelve Months (LTM) is -110% |
| Yield minus risk free rate is negativeERPEquity Risk Premium (ERP) = Total Yield - Risk Free Rate, Reflects the premium above risk free assets offered by the investment. is -13% |
| Key risksPRTA key risks include [1] a heavy dependence on its narrowed pipeline of high-risk neurodegenerative candidates following the Phase 3 failure of its former lead candidate, Show more. |
Qualitative Assessment
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Prothena (PRTA) stock has lost about 15% since 4/30/2026 because of the following key factors:
1. Sharp Decline in Collaboration Revenue in Fiscal Q2 2026.
Prothena reported a substantial decrease in total revenue for fiscal Q2 2026 (ended June 30, 2026) to $1.0 million, compared to $52.1 million in the prior fiscal quarter and $4.4 million in fiscal Q2 2025. This significant quarter-over-quarter drop, following a large $50.0 million milestone payment from Novo Nordisk in fiscal Q1 2026 (ended March 31, 2026), highlighted a reduction in near-term collaboration inflows and contributed to investor uncertainty regarding sustainable revenue generation.
2. Return to Net Loss and Lowered Cash Guidance in Fiscal Q2 2026.
After reporting a net income of $14.1 million for the first six months of 2026, primarily due to the fiscal Q1 milestone payment, Prothena returned to a net loss of $18.6 million in fiscal Q2 2026, despite a significant improvement from the $125.8 million net loss in fiscal Q2 2025. Additionally, the company updated its full-year 2026 projected cash balance, lowering it by $14 million from prior guidance to approximately $259 million (midpoint), partly attributable to cash deployed for share repurchases. These financial results and revised guidance likely fostered a more cautious investor sentiment.
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Prothena (PRTA) stock has lost about 15% since 4/30/2026 because of the following key factors:
1. Sharp Decline in Collaboration Revenue in Fiscal Q2 2026.
Prothena reported a substantial decrease in total revenue for fiscal Q2 2026 (ended June 30, 2026) to $1.0 million, compared to $52.1 million in the prior fiscal quarter and $4.4 million in fiscal Q2 2025. This significant quarter-over-quarter drop, following a large $50.0 million milestone payment from Novo Nordisk in fiscal Q1 2026 (ended March 31, 2026), highlighted a reduction in near-term collaboration inflows and contributed to investor uncertainty regarding sustainable revenue generation.
2. Return to Net Loss and Lowered Cash Guidance in Fiscal Q2 2026.
After reporting a net income of $14.1 million for the first six months of 2026, primarily due to the fiscal Q1 milestone payment, Prothena returned to a net loss of $18.6 million in fiscal Q2 2026, despite a significant improvement from the $125.8 million net loss in fiscal Q2 2025. Additionally, the company updated its full-year 2026 projected cash balance, lowering it by $14 million from prior guidance to approximately $259 million (midpoint), partly attributable to cash deployed for share repurchases. These financial results and revised guidance likely fostered a more cautious investor sentiment.
3. Extended Timelines for Key Clinical Trial Readouts.
Major partnered programs, including prasinezumab in Phase 3 trials with Roche for Parkinson's disease and coramitug in Phase 3 trials with Novo Nordisk for ATTR amyloidosis, have primary completion expected in 2029. This extended timeline for significant clinical catalysts places the company in a "disciplined holding pattern" with limited near-term data readouts that could significantly drive stock performance, leading to investor impatience and a focus on quarterly financial volatility.
4. Mixed Analyst Sentiment and Price Target Adjustments.
While Prothena holds a consensus "Moderate Buy" rating with an average price target around $21.40 to $23.75, implying significant upside, there were notable shifts in analyst sentiment within the period. For instance, Bank of America Securities reiterated a "Sell" rating with an $8.00 price target on May 8, 2026, and Wall Street Zen downgraded the stock from "Buy" to "Hold" on July 25, 2026. Such varied or tempered analyst views can contribute to downward pressure and cautious investor positioning.
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Stock Movement Drivers
Fundamental Drivers
The -16.3% change in PRTA stock from 4/30/2026 to 8/12/2026 was primarily driven by a -85.6% change in the company's P/S Multiple.| (LTM values as of) | 4302026 | 8122026 | Change |
|---|---|---|---|
| Stock Price ($) | 11.06 | 9.26 | -16.3% |
| Change Contribution By: | |||
| Total Revenues ($ Mil) | 10 | 55 | 463.1% |
| P/S Multiple | 61.5 | 8.9 | -85.6% |
| Shares Outstanding (Mil) | 54 | 52 | 3.2% |
| Cumulative Contribution | -16.3% |
Market Drivers
4/30/2026 to 8/12/2026| Return | Correlation | |
|---|---|---|
| PRTA | -16.3% | |
| Market (SPY) | 7.5% | 15.0% |
| Sector (XLV) | 15.4% | 30.8% |
Fundamental Drivers
The 5.1% change in PRTA stock from 1/31/2026 to 8/12/2026 was primarily driven by a 362.7% change in the company's Total Revenues ($ Mil).| (LTM values as of) | 1312026 | 8122026 | Change |
|---|---|---|---|
| Stock Price ($) | 8.81 | 9.26 | 5.1% |
| Change Contribution By: | |||
| Total Revenues ($ Mil) | 12 | 55 | 362.7% |
| P/S Multiple | 40.2 | 8.9 | -78.0% |
| Shares Outstanding (Mil) | 54 | 52 | 3.2% |
| Cumulative Contribution | 5.1% |
Market Drivers
1/31/2026 to 8/12/2026| Return | Correlation | |
|---|---|---|
| PRTA | 5.1% | |
| Market (SPY) | 11.9% | 27.7% |
| Sector (XLV) | 9.3% | 37.8% |
Fundamental Drivers
The 34.8% change in PRTA stock from 7/31/2025 to 8/12/2026 was primarily driven by a 230.3% change in the company's P/S Multiple.| (LTM values as of) | 7312025 | 8122026 | Change |
|---|---|---|---|
| Stock Price ($) | 6.87 | 9.26 | 34.8% |
| Change Contribution By: | |||
| Total Revenues ($ Mil) | 138 | 55 | -60.5% |
| P/S Multiple | 2.7 | 8.9 | 230.3% |
| Shares Outstanding (Mil) | 54 | 52 | 3.2% |
| Cumulative Contribution | 34.8% |
Market Drivers
7/31/2025 to 8/12/2026| Return | Correlation | |
|---|---|---|
| PRTA | 34.8% | |
| Market (SPY) | 23.3% | 27.1% |
| Sector (XLV) | 30.8% | 28.6% |
Fundamental Drivers
The -86.6% change in PRTA stock from 7/31/2023 to 8/12/2026 was primarily driven by a -86.5% change in the company's P/S Multiple.| (LTM values as of) | 7312023 | 8122026 | Change |
|---|---|---|---|
| Stock Price ($) | 68.87 | 9.26 | -86.6% |
| Change Contribution By: | |||
| Total Revenues ($ Mil) | 55 | 55 | -0.7% |
| P/S Multiple | 65.8 | 8.9 | -86.5% |
| Shares Outstanding (Mil) | 53 | 52 | 0.7% |
| Cumulative Contribution | -86.6% |
Market Drivers
7/31/2023 to 8/12/2026| Return | Correlation | |
|---|---|---|
| PRTA | -86.6% | |
| Market (SPY) | 74.7% | 23.3% |
| Sector (XLV) | 31.5% | 25.2% |
Price Returns Compared
| 2021 | 2022 | 2023 | 2024 | 2025 | 2026 | Total [1] | |
|---|---|---|---|---|---|---|---|
| Returns | |||||||
| PRTA Return | 311% | 22% | -40% | -62% | -31% | -3% | -23% |
| Peers Return | 0% | 15% | 9% | -4% | 46% | 1% | 79% |
| S&P 500 Return | 27% | -19% | 24% | 23% | 16% | 13% | 106% |
Monthly Win Rates [3] | |||||||
| PRTA Win Rate | 58% | 50% | 42% | 25% | 58% | 38% | |
| Peers Win Rate | 47% | 55% | 47% | 38% | 58% | 50% | |
| S&P 500 Win Rate | 75% | 42% | 67% | 75% | 67% | 50% | |
Max Drawdowns [4] | |||||||
| PRTA Max Drawdown | -47% | -54% | -59% | -71% | -71% | -31% | |
| Peers Max Drawdown | -40% | -30% | -30% | -34% | -32% | -30% | |
| S&P 500 Max Drawdown | -5% | -25% | -10% | -8% | -19% | -9% | |
[1] Cumulative total returns since the beginning of 2021
[2] Peers: BIIB, LLY, ALNY, IONS, DNLI. See PRTA Returns vs. Peers.
[3] Win Rate = % of calendar months in which monthly returns were positive
[4] Max drawdown represents maximum peak-to-trough decline within a year
[5] 2026 data is for the year up to 8/12/2026 (YTD)
How Low Can It Go
| Event | PRTA | S&P 500 |
|---|---|---|
| 2023 SVB Regional Banking Crisis | ||
| % Loss | -13.0% | -6.7% |
| % Gain to Breakeven | 14.9% | 7.1% |
| Time to Breakeven | 30 days | 31 days |
| 2022 Inflation Shock & Fed Tightening | ||
| % Loss | -53.8% | -24.5% |
| % Gain to Breakeven | 116.5% | 32.4% |
| Time to Breakeven | 107 days | 427 days |
| 2020 COVID-19 Crash | ||
| % Loss | -37.1% | -33.7% |
| % Gain to Breakeven | 58.9% | 50.9% |
| Time to Breakeven | 33 days | 140 days |
| Q4 2018 Fed Policy Error / Growth Scare | ||
| % Loss | -36.5% | -19.2% |
| % Gain to Breakeven | 57.4% | 23.8% |
| Time to Breakeven | 67 days | 105 days |
| 2016-2017 Trump Reflation Bond Selloff | ||
| % Loss | -33.6% | -3.7% |
| % Gain to Breakeven | 50.7% | 3.9% |
| Time to Breakeven | 8 days | 6 days |
| 2015-2016 China Devaluation / Global Growth Scare | ||
| % Loss | -51.5% | -12.2% |
| % Gain to Breakeven | 106.0% | 13.9% |
| Time to Breakeven | 223 days | 62 days |
In The Past
Prothena's stock fell -8.3% during the 2024 Yen Carry Trade Unwind. Such a loss loss requires a 9.1% gain to breakeven.
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Asset Allocation
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| Event | PRTA | S&P 500 |
|---|---|---|
| 2022 Inflation Shock & Fed Tightening | ||
| % Loss | -53.8% | -24.5% |
| % Gain to Breakeven | 116.5% | 32.4% |
| Time to Breakeven | 107 days | 427 days |
| 2020 COVID-19 Crash | ||
| % Loss | -37.1% | -33.7% |
| % Gain to Breakeven | 58.9% | 50.9% |
| Time to Breakeven | 33 days | 140 days |
| Q4 2018 Fed Policy Error / Growth Scare | ||
| % Loss | -36.5% | -19.2% |
| % Gain to Breakeven | 57.4% | 23.8% |
| Time to Breakeven | 67 days | 105 days |
| 2016-2017 Trump Reflation Bond Selloff | ||
| % Loss | -33.6% | -3.7% |
| % Gain to Breakeven | 50.7% | 3.9% |
| Time to Breakeven | 8 days | 6 days |
| 2015-2016 China Devaluation / Global Growth Scare | ||
| % Loss | -51.5% | -12.2% |
| % Gain to Breakeven | 106.0% | 13.9% |
| Time to Breakeven | 223 days | 62 days |
| 2014-2016 Oil Price Collapse | ||
| % Loss | -23.7% | -6.8% |
| % Gain to Breakeven | 31.0% | 7.3% |
| Time to Breakeven | 28 days | 15 days |
In The Past
Prothena's stock fell -8.3% during the 2024 Yen Carry Trade Unwind. Such a loss loss requires a 9.1% gain to breakeven.
Preserve Wealth
Limiting losses and compounding gains is essential to preserving wealth.
Asset Allocation
Actively managed asset allocation strategies protect wealth. Learn more.
About Prothena (PRTA)
Prothena Corporation plc (PRTA) is a late-stage clinical biopharmaceutical company dedicated to the discovery and development of novel therapeutic candidates for serious, life-threatening diseases. Operating primarily in the United States, Prothena's core focus is on addressing conditions related to protein misfolding, particularly neurodegenerative diseases and systemic amyloidosis. As a clinical company, its primary activity involves advancing drug candidates through various phases of clinical trials, rather than selling commercially approved products.
The company's pipeline includes several investigational therapies targeting significant unmet medical needs. Its most advanced candidate is Birtamimab, an antibody currently in Phase III clinical trials for the treatment of AL amyloidosis. Another key program, Prasinezumab, a humanized monoclonal antibody for Parkinson's disease, is in Phase IIb clinical trials. Prothena also has multiple programs in earlier stages for Alzheimer's disease, including PRX005 in Phase I and PRX012 in preclinical development, alongside PRX004 which completed Phase I for Transthyretin amyloidosis.
Prothena's business model involves developing these potential therapies, often in collaboration with larger pharmaceutical partners such as F. Hoffmann-La Roche Ltd. and Bristol-Myers Squibb. The primary market Prothena aims to serve comprises patients suffering from debilitating and life-threatening conditions like AL amyloidosis, Parkinson's disease, and Alzheimer's disease. By developing innovative antibodies and vaccines, the company seeks to provide new treatment and prevention options for these severe diseases globally.
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Here are 1-3 brief analogies to describe Prothena:
- Like a clinical-stage Biogen or Eli Lilly, focused on breakthrough treatments for Alzheimer's, Parkinson's, and rare protein diseases.
- An early-stage Genentech or Amgen, concentrated purely on developing novel therapies for challenging neurological and rare diseases.
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- Birtamimab: An investigational humanized antibody in Phase III clinical trial for the treatment of AL amyloidosis.
- Prasinezumab: A humanized monoclonal antibody in Phase IIb clinical trial for the treatment of Parkinson's disease.
- PRX004: An investigational therapy that completed Phase I clinical trial for the treatment of Transthyretin amyloidosis.
- PRX005: An investigational therapy in Phase I clinical trial for the treatment of Alzheimer's disease.
- PRX012: A discovery and preclinical program targeting Alzheimer's disease.
- Dual Aß-Tau vaccine: A discovery and preclinical program for the treatment and prevention of Alzheimer's disease.
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Prothena (PRTA) primarily operates by discovering and developing novel therapies and then entering into licensing, development, and commercialization agreements with larger pharmaceutical companies. Therefore, its major customers are other companies, not individuals.
Based on the provided information, Prothena's major customer companies are:
- F. Hoffmann-La Roche Ltd. (and Hoffmann-La Roche Inc.)
- Bristol-Myers Squibb (NYSE: BMY)
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Dr. Kinney has served as Prothena's President and Chief Executive Officer since September 2016, and as a Director since the same month. Prior to his appointment as CEO, he was the company's Chief Operating Officer for part of 2016, and before that, he held the roles of Chief Scientific Officer and Head of Research and Development from 2012 to 2016. Dr. Kinney was a founding member of Prothena's leadership team when the company spun out of Elan in 2012. His earlier career includes various leadership positions at Elan Pharmaceuticals Inc., where he served as Vice President, Pharmacology, and Senior Vice President of Pharmacological Sciences. He also held responsibility for overseeing nonclinical research at Janssen Alzheimer Immunotherapy R&D, and worked at Merck Research Laboratories as Senior Director, Head of Central Pharmacology, contributing to drug discovery and leading programs for neurodegenerative and psychiatric conditions. Additionally, Dr. Kinney held positions at Bristol Myers Squibb and was an Assistant Professor at the Emory University School of Medicine.
Tran B. Nguyen, Chief Strategy Officer and Chief Financial Officer
Mr. Nguyen has been Prothena's Chief Financial Officer since 2013 and took on the role of Chief Strategy Officer in September 2021. He also served as the Chief Operating Officer from June 2018 to September 2021. With over 25 years of experience in biotech finance, banking, and private equity industries, Mr. Nguyen has a strong background in financial leadership. Before joining Prothena, he held Chief Financial Officer positions at Somaxon Pharmaceuticals, Inc. from 2010 until its acquisition in 2013, and at Metabasis Therapeutics, Inc. from 2009 until its sale in 2010. His experience also includes healthcare investment banking roles at Citi and Lehman Brothers. Mr. Nguyen's background reflects a pattern of managing companies involved in acquisitions, having been CFO at two biotechs through sale transactions. He currently serves on the board of directors of Rain Oncology Inc. and previously served on the board of Sierra Oncology, Inc.
Chad J. Swanson, Ph.D., Chief Development Officer
Dr. Swanson was appointed Chief Development Officer of Prothena in September 2024, joining the executive leadership team. He first came to Prothena in January 2023 as Senior Vice President and Head of Clinical Development. Dr. Swanson is a neuropharmacologist with over 20 years of industry experience. Before his tenure at Prothena, he was the Executive Director of Clinical Research in the Alzheimer's Disease Brain Health group at Eisai, Inc., where he led the lecanemab program as the International Project Team Leader.
Michael J. Malecek, Chief Legal Officer and Company Secretary
Mr. Malecek serves as Prothena's Chief Legal Officer and Company Secretary.
Wagner M. Zago, Chief Scientific Officer
Mr. Zago holds the position of Chief Scientific Officer at Prothena.
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The key risks to Prothena's business are primarily centered around the challenging and high-stakes nature of biopharmaceutical development, particularly in neurodegenerative and rare diseases.
- Clinical Trial Failure and Regulatory Approval Risk: Prothena, as a late-stage clinical company, faces significant inherent risks associated with its investigational therapies failing to meet primary or secondary endpoints in clinical trials or subsequently failing to obtain regulatory approval. This risk was recently demonstrated by the discontinuation of its wholly-owned birtamimab program in May 2025, following its failure to meet endpoints in the Phase 3 AFFIRM-AL clinical trial for AL amyloidosis. This setback resulted in a strategic pivot for the company, including a substantial workforce reduction, and heightened reliance on the success of its remaining pipeline, particularly PRX012 for Alzheimer's disease, an area known for high clinical trial failure rates.
- Reliance on a Limited and Concentrated Pipeline: Following the discontinuation of its birtamimab program, Prothena's pipeline has become more concentrated. This increases the company's dependence on the successful development and eventual commercialization of a smaller number of key assets, such as PRX012. Any significant setback or delay in these remaining programs would have a disproportionately large impact on Prothena's valuation, financial performance, and future prospects.
- Dependence on Strategic Collaborations: Prothena relies significantly on its license, development, and commercialization agreements with major pharmaceutical partners, including F. Hoffmann-La Roche Ltd. and Bristol-Myers Squibb, for the advancement of several pipeline candidates like prasinezumab and PRX019. These collaborations are crucial for funding, development, and potential commercialization. Any changes in these strategic relationships, such as shifts in partner priorities, funding commitments, or adverse outcomes in partnered clinical trials (like the missed primary endpoint for prasinezumab in the PADOVA study), could negatively affect Prothena's business and financial standing.
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Prothena Corporation plc (PRTA) focuses on developing therapies for several life-threatening diseases, each representing a significant addressable market.
Addressable Markets for Prothena's Main Products:
- Birtamimab (AL amyloidosis): The global AL amyloidosis therapeutics market was valued at approximately $3.81 billion in 2024 across the top 7 major markets (US, EU4, UK, and Japan), and is projected to reach about $15.00 billion by 2035. The U.S. market alone for AL amyloidosis therapeutics is estimated at $0.86 billion in 2024, with a projection to reach approximately $1.22 billion by 2030.
- Prasinezumab (Parkinson's disease): The global Parkinson's disease therapeutics market was valued at $6.2 billion in 2024 and is projected to reach $13.3 billion by 2034. The Parkinson's disease treatment market in the United States is expected to reach a projected revenue of $2.60 billion by 2030. Another estimate places the US Parkinson's Disease Therapeutics Market Size at $1.45 billion in 2024, projected to grow to $3.50 billion by 2035.
- PRX004 (Transthyretin amyloidosis - ATTR amyloidosis): The global transthyretin amyloidosis treatment market was valued at $7.81 billion in 2024 and is expected to reach $17.80 billion by 2032. In the U.S., the transthyretin amyloidosis treatment market size was valued at $3.11 billion in 2024 and is expected to reach $6.92 billion by 2032.
- PRX005, PRX012, and dual Aß-Tau vaccine (Alzheimer's disease): The global Alzheimer's disease market in the 7MM (US, EU4, UK, and Japan) was valued at approximately $3.61 billion in 2023 and is projected to reach $34.33 billion by 2034. The Alzheimer's disease market is estimated to grow from $11.3 billion in 2024 to $12.4 billion in 2025 and $29.4 billion by 2035 globally. In the United States, the Alzheimer's drugs market size was worth $1.62 billion in 2022.
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- Milestone Payments from Roche Collaboration for Prasinezumab: Prothena is eligible for significant milestone payments as its partner, Roche, advances prasinezumab into Phase III development for early-stage Parkinson's disease, a stage initiated in the fourth quarter of 2025. Prothena could receive up to $620 million in additional milestone payments from this collaboration.
- Milestone Payments from Novo Nordisk Collaboration for Coramitug: Prothena anticipates further milestone payments from its collaboration with Novo Nordisk for coramitug, an amyloid depleter antibody in Phase III development for ATTR cardiomyopathy. A clinical milestone payment is specifically expected in the first half of 2026 upon meeting prespecified enrollment targets in the ongoing Phase III CLEOPATTRA study. Prothena is eligible for up to $1.13 billion in total development and sales milestones from this partnership.
- Milestone Payments from Bristol-Myers Squibb (BMS) Collaborations for PRX019 and BMS-986446: The advancement of programs partnered with BMS is a key revenue driver. Prothena expects to complete the Phase I trial for PRX019 in 2026, which could trigger a milestone payment if BMS decides to pursue further development. Additionally, the Phase II TargetTau-1 clinical trial for BMS-986446 in early Alzheimer's disease, which was fully enrolled in 2025, is expected to complete in the first half of 2027, potentially leading to further development milestones. Prothena is eligible for up to an additional $1.7 billion for regulatory and commercial milestone payments across multiple programs in this collaboration.
- Upfront and Milestone Payments from Potential New Collaboration and Licensing Deals: Prothena continues to engage in business development activities, including exploring partnership opportunities for its wholly-owned assets such as PRX012-TfR and its novel preclinical platforms like TDP-43 CYTOPE. Any new collaboration or licensing agreements for these programs could result in upfront payments and future development milestones, contributing to revenue growth within the forecast period.
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Share Repurchases
- Prothena's board authorized a share repurchase program of up to $100.0 million, announced on February 27, 2026.
- This program is set to expire on December 31, 2026.
- As of December 31, 2025, prior to any repurchases under this plan, Prothena held $308.4 million in cash, cash equivalents, and restricted cash with no debt.
Share Issuance
- The number of ordinary shares outstanding was approximately 53.7 million as of February 9, 2024.
- The number of ordinary shares outstanding was approximately 53.8 million as of February 20, 2025, and February 12, 2026.
- Prothena filed a registration statement (S-8) to enable equity awards under its amended 2018 Long Term Incentive Plan.
Inbound Investments
- In 2024, Prothena received an $80 million payment from Bristol Myers Squibb (BMS) for the exclusive global license for PRX019.
- In 2023, Bristol Myers Squibb opted into global rights for BMS-986446 (formerly PRX005), triggering a $55 million milestone payment.
- Prothena anticipates up to $105 million in aggregate clinical milestone payments from strategic partners (Novo Nordisk and Bristol Myers Squibb) in 2026.
Capital Expenditures
- Capital expenditures were reported as $0.30 million in 2024.
- Capital expenditures were reported as $2.77 million in 2023.
- Capital expenditures were reported as $0.46 million in 2022.
Peer Outperformance in Biotechnology
| Industry | Names | 1Y med | 3Y med | 5Y med | Top 3 by 5Y |
|---|---|---|---|---|---|
| Health Care Distributors | 7 | 9.5% | 71.6% | 176.5% | CAH 405% · MCK 354% · SNYR 198% |
| Health Care Services | 20 | 24.8% | 33.4% | 10.1% | HIMS 258% · RDNT 152% · DGX 77% |
| Managed Health Care | 8 | 51.3% | -4.8% | 7.2% | OSCR 101% · HQY 54% · ELV 17% |
| Health Care Equipment | 51 | -2.7% | -10.6% | -17.3% | POCI 10275% · UFPT 417% · GKOS 281% |
| Health Care Facilities | 24 | 12.4% | -11.0% | -18.8% | THC 281% · NHC 239% · ENSG 120% |
| Health Care Supplies | 12 | 41.4% | -12.0% | -25.5% | LNTH 295% · HAE 49% · MMSI 38% |
| Pharmaceuticals | 64 | 4.2% | -3.0% | -40.0% | LQDA 2862% · INDV 1521% · ETON 841% |
| Health Care Technology | 21 | -15.2% | -55.4% | -72.3% | SPOK 135% · TALK 0% · HSTM -6% |
| Life Sciences Tools & Services | 111 | -4.3% | -34.4% | -72.6% | SNWV 2092% · ELMD 263% · MEDP 236% |
| Biotechnology ← | 372 | 12.1% | -29.2% | -77.3% | BRTX 106050% · DNTH 1643% · CELZ 1614% |
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Wealth Management
Peer Comparisons
| Peers to compare with: |
Financials
| Median | |
|---|---|
| Name | |
| Mkt Price | 132.70 |
| Mkt Cap | 19.6 |
| Rev LTM | 2,839 |
| Op Inc LTM | 470 |
| FCF LTM | 380 |
| FCF 3Y Avg | 118 |
| CFO LTM | 426 |
| CFO 3Y Avg | 149 |
Growth & Margins
| Median | |
|---|---|
| Name | |
| Rev Chg LTM | 49.6% |
| Rev Chg 3Y Avg | 39.4% |
| Rev Chg Q | 3.4% |
| QoQ Delta Rev Chg LTM | 0.9% |
| Op Inc Chg LTM | 37.1% |
| Op Inc Chg 3Y Avg | -11.2% |
| Op Mgn LTM | -24.4% |
| Op Mgn 3Y Avg | 6.0% |
| QoQ Delta Op Mgn LTM | 2.4% |
| CFO/Rev LTM | -18.9% |
| CFO/Rev 3Y Avg | 11.1% |
| FCF/Rev LTM | -24.0% |
| FCF/Rev 3Y Avg | 2.5% |
Price Behavior
| Market Price | $9.26 | |
| Market Cap ($ Bil) | 0.5 | |
| First Trading Date | 12/21/2012 | |
| Distance from 52W High | -19.5% | |
| 50 Days | 200 Days | |
| DMA Price | $8.83 | $9.59 |
| DMA Trend | down | down |
| Distance from DMA | 4.9% | -3.5% |
| 3M | 1YR | |
| Volatility | 46.9% | 47.7% |
| Downside Capture | 16.87 | 108.30 |
| Upside Capture | -2.01 | 108.01 |
| Correlation (SPY) | 14.9% | 26.7% |
| 1M | 2M | 3M | 6M | 1Y | 3Y | |
|---|---|---|---|---|---|---|
| Beta | -1.07 | 0.02 | 0.46 | 0.93 | 1.02 | 0.98 |
| Up Beta | -0.89 | 1.22 | 1.62 | 1.60 | 1.33 | 0.46 |
| Down Beta | -0.88 | 0.92 | 0.39 | 0.24 | 0.37 | 1.31 |
| Up Capture | -234% | -124% | -53% | 65% | 121% | 27% |
| Bmk +ve Days | 11 | 22 | 35 | 67 | 138 | 427 |
| Stock +ve Days | 9 | 17 | 27 | 57 | 114 | 346 |
| Down Capture | 27% | 5% | 89% | 109% | 111% | 110% |
| Bmk -ve Days | 11 | 21 | 28 | 59 | 114 | 326 |
| Stock -ve Days | 12 | 25 | 35 | 67 | 133 | 397 |
[1] Upside and downside betas calculated using positive and negative benchmark daily returns respectively
Based On 1-Year Data
| Annualized Return | Annualized Volatility | Sharpe Ratio | Correlation with PRTA | |
|---|---|---|---|---|
| PRTA | 20.8% | 47.7% | 0.54 | - |
| Sector ETF (XLV) | 31.1% | 15.5% | 1.54 | 32.2% |
| Equity (SPY) | 22.6% | 12.8% | 1.32 | 26.7% |
| Gold (GLD) | 31.4% | 28.4% | 0.95 | 18.0% |
| Commodities (DBC) | 37.9% | 20.1% | 1.48 | -14.7% |
| Real Estate (VNQ) | 14.3% | 13.8% | 0.73 | 22.0% |
| Bitcoin (BTCUSD) | -46.5% | 42.9% | -1.33 | 29.1% |
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Based On 5-Year Data
| Annualized Return | Annualized Volatility | Sharpe Ratio | Correlation with PRTA | |
|---|---|---|---|---|
| PRTA | -29.9% | 75.2% | -0.18 | - |
| Sector ETF (XLV) | 6.4% | 15.0% | 0.24 | 30.0% |
| Equity (SPY) | 13.4% | 17.2% | 0.60 | 31.6% |
| Gold (GLD) | 19.0% | 18.6% | 0.83 | 7.8% |
| Commodities (DBC) | 9.8% | 19.6% | 0.39 | 3.9% |
| Real Estate (VNQ) | 2.2% | 18.9% | 0.01 | 27.5% |
| Bitcoin (BTCUSD) | 9.9% | 52.8% | 0.37 | 19.3% |
Smart multi-asset allocation framework can stack odds in your favor. Learn How
Based On 10-Year Data
| Annualized Return | Annualized Volatility | Sharpe Ratio | Correlation with PRTA | |
|---|---|---|---|---|
| PRTA | -16.4% | 75.4% | 0.11 | - |
| Sector ETF (XLV) | 10.2% | 16.6% | 0.50 | 30.9% |
| Equity (SPY) | 15.4% | 17.9% | 0.73 | 30.8% |
| Gold (GLD) | 12.0% | 16.2% | 0.61 | 6.4% |
| Commodities (DBC) | 8.0% | 18.0% | 0.36 | 11.0% |
| Real Estate (VNQ) | 4.7% | 20.7% | 0.19 | 22.4% |
| Bitcoin (BTCUSD) | 60.9% | 66.1% | 1.01 | 9.7% |
Smart multi-asset allocation framework can stack odds in your favor. Learn How
Earnings Returns History
Updated 8/11/2026| Forward Returns | |||
|---|---|---|---|
| Earnings Date | 1D Returns | 5D Returns | 21D Returns |
| 8/6/2026 | 2.1% | ||
| 5/7/2026 | 2.0% | -6.3% | -18.6% |
| 2/19/2026 | -0.1% | -4.3% | -3.1% |
| 11/6/2025 | 4.8% | 1.0% | 2.4% |
| 8/4/2025 | 1.3% | 10.5% | 20.9% |
| 5/8/2025 | 4.6% | -5.4% | -26.1% |
| 2/20/2025 | 2.0% | -0.8% | -15.0% |
| 11/12/2024 | -0.7% | -19.1% | -20.4% |
| ... | |||
| SUMMARY STATS | |||
| # Positive | 13 | 10 | 10 |
| # Negative | 12 | 14 | 14 |
| Median Positive | 4.4% | 4.4% | 6.0% |
| Median Negative | -2.9% | -5.0% | -16.0% |
| Max Positive | 12.0% | 51.0% | 93.8% |
| Max Negative | -8.3% | -19.1% | -26.1% |
| Forward Returns | |||
|---|---|---|---|
| Earnings Date | 1D Returns | 5D Returns | 21D Returns |
| 8/6/2026 | 2.1% | ||
| 5/7/2026 | 2.0% | -6.3% | -18.6% |
| 2/19/2026 | -0.1% | -4.3% | -3.1% |
| 11/6/2025 | 4.8% | 1.0% | 2.4% |
| 8/4/2025 | 1.3% | 10.5% | 20.9% |
| 5/8/2025 | 4.6% | -5.4% | -26.1% |
| 2/20/2025 | 2.0% | -0.8% | -15.0% |
| 11/12/2024 | -0.7% | -19.1% | -20.4% |
| 8/8/2024 | 4.4% | 6.0% | 3.7% |
| 5/8/2024 | -4.5% | -2.8% | -8.3% |
| 2/15/2024 | -1.8% | -4.6% | -12.0% |
| 11/2/2023 | 7.4% | -6.3% | 0.9% |
| 8/3/2023 | -7.3% | -6.2% | -17.1% |
| 5/4/2023 | 12.0% | 4.7% | -1.3% |
| 2/23/2023 | 7.1% | 4.1% | -7.5% |
| 11/3/2022 | -5.4% | -1.0% | 4.7% |
| 8/8/2022 | -8.3% | -1.1% | -18.9% |
| 5/5/2022 | 2.7% | -15.2% | -9.7% |
| 2/17/2022 | -4.0% | 0.7% | 7.4% |
| 11/4/2021 | 4.4% | 0.1% | -21.9% |
| 8/5/2021 | 2.6% | 5.1% | 27.6% |
| 5/11/2021 | -4.9% | 3.7% | 93.8% |
| 2/11/2021 | -0.2% | 51.0% | 46.5% |
| 11/4/2020 | -1.5% | -11.1% | -17.3% |
| 8/6/2020 | -1.5% | -1.3% | 2.9% |
| SUMMARY STATS | |||
| # Positive | 13 | 10 | 10 |
| # Negative | 12 | 14 | 14 |
| Median Positive | 4.4% | 4.4% | 6.0% |
| Median Negative | -2.9% | -5.0% | -16.0% |
| Max Positive | 12.0% | 51.0% | 93.8% |
| Max Negative | -8.3% | -19.1% | -26.1% |
SEC Filings
Expand for More| Report Date | Filing Date | Filing |
|---|---|---|
| 06/30/2026 | 08/06/2026 | 10-Q |
| 03/31/2026 | 05/07/2026 | 10-Q |
| 12/31/2025 | 02/27/2026 | 10-K |
| 09/30/2025 | 11/06/2025 | 10-Q |
| 06/30/2025 | 08/04/2025 | 10-Q |
| 03/31/2025 | 05/08/2025 | 10-Q |
| 12/31/2024 | 02/27/2025 | 10-K |
| 09/30/2024 | 11/12/2024 | 10-Q |
| 06/30/2024 | 08/08/2024 | 10-Q |
| 03/31/2024 | 05/08/2024 | 10-Q |
| 12/31/2023 | 02/22/2024 | 10-K |
| 09/30/2023 | 11/02/2023 | 10-Q |
| 06/30/2023 | 08/03/2023 | 10-Q |
| 03/31/2023 | 05/04/2023 | 10-Q |
| 12/31/2022 | 02/28/2023 | 10-K |
| 09/30/2022 | 11/03/2022 | 10-Q |
| Report Date | Filing Date | Filing |
|---|---|---|
| 06/30/2026 | 08/06/2026 | 10-Q |
| 03/31/2026 | 05/07/2026 | 10-Q |
| 12/31/2025 | 02/27/2026 | 10-K |
| 09/30/2025 | 11/06/2025 | 10-Q |
| 06/30/2025 | 08/04/2025 | 10-Q |
| 03/31/2025 | 05/08/2025 | 10-Q |
| 12/31/2024 | 02/27/2025 | 10-K |
| 09/30/2024 | 11/12/2024 | 10-Q |
| 06/30/2024 | 08/08/2024 | 10-Q |
| 03/31/2024 | 05/08/2024 | 10-Q |
| 12/31/2023 | 02/22/2024 | 10-K |
| 09/30/2023 | 11/02/2023 | 10-Q |
| 06/30/2023 | 08/03/2023 | 10-Q |
| 03/31/2023 | 05/04/2023 | 10-Q |
| 12/31/2022 | 02/28/2023 | 10-K |
| 09/30/2022 | 11/03/2022 | 10-Q |
| 06/30/2022 | 08/08/2022 | 10-Q |
| 03/31/2022 | 05/05/2022 | 10-Q |
| 12/31/2021 | 02/25/2022 | 10-K |
| 09/30/2021 | 11/04/2021 | 10-Q |
| 06/30/2021 | 08/05/2021 | 10-Q |
| 03/31/2021 | 05/11/2021 | 10-Q |
| 12/31/2020 | 02/26/2021 | 10-K |
| 09/30/2020 | 11/04/2020 | 10-Q |
| 06/30/2020 | 08/06/2020 | 10-Q |
| 03/31/2020 | 05/06/2020 | 10-Q |
| 12/31/2019 | 03/03/2020 | 10-K |
| 09/30/2019 | 11/05/2019 | 10-Q |
Recent Forward Guidance
Updated 8/7/2026Latest: Q2 2026 Earnings Reported 8/6/2026
| Forward Guidance | Guidance Change | ||||||
|---|---|---|---|---|---|---|---|
| Metric | Low | Mid | High | % Chg | % Delta | Change | Prior |
| 2026 Net Cash Used in Operating and Investing Activities | 18.00 Mil | 20.50 Mil | 23.00 Mil | 0 | Affirmed | Guidance: 20.50 Mil for 2026 | |
| 2026 Year End Cash Balance | 259.00 Mil | -5.1% | Lowered | Guidance: 273.00 Mil for 2026 | |||
| 2026 Net Loss | -30.00 Mil | -27.50 Mil | -25.00 Mil | 0 | Affirmed | Guidance: -27.50 Mil for 2026 | |
| 2026 Non-cash Share-based Compensation Expense | 26.00 Mil | ||||||
Insider Activity
Updated 8/10/2026| # | Owner | Title | Holding | Action | Filing Date | Price | Shares | Transacted Value | Value of Held Shares | Form |
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | Scully, William P | Direct | Buy | 8102026 | 8.62 | 34,000 | 293,053 | 6,809,168 | Form | |
| 2 | Scully, William P | Manatee Equity Fund LLC | Buy | 8102026 | 8.62 | 3,500 | 30,167 | 719,703 | Form | |
| 3 | Kingston, Anne Evans | Chief Strategy Officer | Direct | Sell | 7302026 | 8.47 | 7,662 | 64,919 | 472,635 | Form |
| 4 | Isaacs, Michael John | General Counsel & Company Sec. | Direct | Sell | 7302026 | 8.47 | 8,386 | 71,055 | 302,871 | Form |
| 5 | Scully, William P | Direct | Buy | 6182026 | 7.90 | 20,000 | 157,990 | 5,972,022 | Form |
| # | Owner | Title | Holding | Action | Filing Date | Price | Shares | Transacted Value | Value of Held Shares | Form |
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | Scully, William P | Direct | Buy | 8102026 | 8.62 | 34,000 | 293,053 | 6,809,168 | Form | |
| 2 | Scully, William P | Manatee Equity Fund LLC | Buy | 8102026 | 8.62 | 3,500 | 30,167 | 719,703 | Form | |
| 3 | Kingston, Anne Evans | Chief Strategy Officer | Direct | Sell | 7302026 | 8.47 | 7,662 | 64,919 | 472,635 | Form |
| 4 | Isaacs, Michael John | General Counsel & Company Sec. | Direct | Sell | 7302026 | 8.47 | 8,386 | 71,055 | 302,871 | Form |
| 5 | Scully, William P | Direct | Buy | 6182026 | 7.90 | 20,000 | 157,990 | 5,972,022 | Form | |
| 6 | Scully, William P | Direct | Buy | 6122026 | 8.17 | 125,000 | 1,021,225 | 8,668,158 | Form | |
| 7 | Scully, William P | Direct | Buy | 6052026 | 9.31 | 50,000 | 465,295 | 8,710,322 | Form | |
| 8 | Scully, William P | Direct | Buy | 6032026 | 9.43 | 50,000 | 471,300 | 8,351,436 | Form | |
| 9 | Scully, William P | Direct | Buy | 5262026 | 9.81 | 100,000 | 981,300 | 8,203,668 | Form |
Industry Resources
External Quote Links
| Y Finance | Barrons |
| TradingView | Morningstar |
| SeekingAlpha | ValueLine |
| Motley Fool | Robinhood |
| CNBC | Etrade |
| MarketWatch | Unusual Whales |
| YCharts | Perplexity Finance |
| FinViz |
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