Prothena (PRTA) AI Stock Analysis

• Market Cap: $495.80M
• Dividend Yield: N/A
• Average Volume (3M): 732.47K
• Price to Earnings (P/E): ―
• Beta (1Y): 0.96
• Revenue Growth: -91.16%
• EPS Growth: -112.24%
• Country: US
• Employees: 163
• Sector: Healthcare
• Sector Strength: 45
• Industry: Biotechnology
• EPS (TTM): -0.40
• Shares Outstanding: 53,832,980
• 10 Day Avg. Volume: 686,318
• 30 Day Avg. Volume: 732,465
• PEG Ratio: -0.02
• Price to Book (P/B): 1.83
• Price to Sales (P/S): 53.08
• P/FCF Ratio: -3.14
• Enterprise Value/Market Cap: 0.41
• Enterprise Value/Revenue: 20.87
• Enterprise Value/Gross Profit: -10.01
• Enterprise Value/Ebitda: -1.16
• 1Y Price Target: $20.80
• Price Target Upside: 125.84% Upside
• Rating Consensus: Moderate Buy
• Number of Analyst Covering: 5
• EPS Forecast (FY): 0.96
• Revenue Forecast (FY): $111.78M

• Rating: 51 Neutral
• Price Target: $9.50 ▲(3.15% Upside)
• Action: Reiterated Date: 02/28/26
• Date: Action: Reiterated 02/28/26

The score is held back primarily by weak financial performance (inconsistent revenue, heavy recent losses, and persistent cash burn) and bearish-to-soft technicals. This is partly offset by a relatively strong earnings-call backdrop (partner programs moving into Phase III and a solid cash position) and a modestly supportive buyback authorization, while valuation remains difficult to anchor due to negative earnings and no dividend yield.

Positive Factors

Partner validation and late‑stage advancement

Advancement of partner programs into Phase III materially de‑risks Prothena’s ability to realize milestone and royalty value over time. Partner execution provides development funding, regulatory expertise and large trial capacity, increasing the probability of downstream commercial milestones and durable cash inflows.

Strong cash position and low leverage

A cash balance north of $300M and minimal leverage give Prothena runway to fund multiple programs and optionality on milestones without immediate financing. This preserves strategic flexibility for trials, BD or selective buybacks and reduces near‑term liquidity risk versus highly leveraged peers.

CYTOPE platform and intracellular targeting progress

CYTOPE’s demonstrated preclinical CNS activity on TDP‑43 expands Prothena’s modality reach into intracellular targets, creating a durable R&D asset. Platform-level capabilities can generate multiple programs, attract collaborations, and diversify long‑term pipeline risk beyond extracellular antibodies.

Negative Factors

Persistent cash burn and negative operating cash flow

Sustained negative operating and free cash flow drives ongoing funding needs even with a sizable cash stockpile. Continued burn increases the probability of future equity financing or milestone‑linked dilution, constrains discretionary spending, and elevates execution risk for multi‑year programs.

Dependence on partners for key programs and data control

Material programs under partner control limit Prothena’s ability to drive timing, disclosure and commercialization decisions. This dependence reduces visible catalysts, links revenue recognition to third‑party choices, and creates strategic execution risk that can delay or mute long‑term value realization.

Safety and competitive technical risk for brain delivery

Safety issues (ARIA‑E) forcing re‑engineering increase development time, costs and technical risk for CNS programs. Combined with multiple competing TfR platforms and unproven mechanism transferability, this undermines differentiation and raises the chance of delayed or diminished commercial outcomes.

Prothena Business Overview & Revenue Model

Company Description

Prothena Corporation plc, a late-stage clinical company, focuses on discovery and development of novel therapies for life-threatening diseases in the United States. The company is involved in developing Birtamimab, an investigational humanized antibody that is in Phase III clinical trial for the treatment of AL amyloidosis; Prasinezumab, a humanized monoclonal antibody, which is in Phase IIb clinical trial for the treatment of Parkinson's disease; PRX004 that completed Phase I clinical trial for the treatment of Transthyretin amyloidosis; and PRX005, which is in Phase I clinical trial for the treatment of Alzheimer's disease. Its discovery and preclinical programs include PRX012 for the treatment of Alzheimer's disease; and dual Aß-Tau vaccine for the treatment and prevention of Alzheimer's disease. Prothena Corporation plc has a license, development, and commercialization agreement with F. Hoffmann-La Roche Ltd. and Hoffmann-La Roche Inc. to develop and commercialize antibodies that target alpha-synuclein; and a collaboration agreement with Bristol-Myers Squibb to develop antibodies. The company was founded in 2012 and is based in Dublin, Ireland.

How the Company Makes Money

Prothena primarily generates revenue through collaboration and license arrangements rather than product sales (it is a clinical-stage company and, to the extent it has no commercialized products, product revenue is null). Under these partnerships, Prothena can earn (1) upfront payments for granting rights to develop and/or commercialize specific programs, (2) research and development reimbursement and/or cost-sharing payments tied to collaborative activities, (3) milestone payments triggered by development, regulatory, or commercial events (e.g., dosing first patient in a trial, successful trial outcomes, regulatory approvals, sales thresholds), and (4) royalties on net sales if a partnered product is commercialized. The company’s reported revenue in periods is therefore typically driven by the timing of recognized collaboration revenue (including amortization/recognition of upfront consideration) and the achievement of contractual milestones, which can make revenue uneven from quarter to quarter. Prothena also funds operations through financing (e.g., issuing equity), but financing proceeds are not revenue under accounting standards.

Prothena Financial Statement Overview

Summary

Financials are pressured by inconsistent, milestone-driven revenue and a return to deep losses in 2022–2025 after profitability in 2021. Cash flow remains meaningfully negative with sustained free cash flow burn, raising future funding risk despite a conservatively financed balance sheet with low leverage.

Income Statement

Revenue has been volatile and recently contracted (2025 revenue down ~18% vs. 2024 after strong growth in 2023–2024). Profitability is the core issue: the company swung from meaningful profitability in 2021 (positive operating profit and net income) to deep losses in 2022–2025, with 2025 showing extremely weak margins driven by very low revenue relative to the cost base. A key positive is the historical ability to generate high revenue in some years (e.g., 2021 and 2024), but the earnings profile lacks consistency and remains heavily loss-making in the most recent period.

Balance Sheet

Leverage is low across the period, with debt modest relative to equity (debt-to-equity roughly ~1%–5% in 2021–2025), which provides financial flexibility for a biotech business. However, equity has declined materially from 2022 to 2025, consistent with sustained losses, and returns on equity are strongly negative in recent years (especially 2025), signaling ongoing value erosion. Overall, the balance sheet looks conservatively financed, but the trajectory of shrinking equity is a meaningful risk if losses persist.

Cash Flow

Cash generation has deteriorated sharply from 2021 (positive operating cash flow and free cash flow) to persistent, sizable cash burn in 2022–2025 (each year negative operating cash flow and negative free cash flow). While cash burn improved slightly in 2024 vs. 2023, it worsened again in 2025, and free cash flow growth is negative in the latest year. A relative positive is that cash flow and net income generally move in the same direction (losses paired with cash outflows), but the current run-rate suggests continued funding needs unless revenues rebound or costs come down.

Breakdown	Dec 2025	Dec 2024	Dec 2023	Dec 2022	Dec 2021
Income Statement
Total Revenue	9.68M	135.16M	91.37M	53.91M	200.58M
Gross Profit	5.98M	135.16M	91.37M	53.91M	200.58M
EBITDA	-197.13M	-153.67M	-190.11M	-130.81M	73.09M
Net Income	-244.09M	-122.31M	-147.03M	-116.95M	66.97M
Balance Sheet
Total Assets	326.80M	547.11M	696.38M	758.03M	609.37M
Cash, Cash Equivalents and Short-Term Investments	307.53M	471.39M	618.83M	710.41M	579.09M
Total Debt	13.86M	10.84M	11.84M	6.47M	12.33M
Total Liabilities	46.33M	60.18M	135.02M	135.99M	143.32M
Stockholders Equity	280.47M	486.93M	561.37M	622.04M	466.04M
Cash Flow
Free Cash Flow	-163.72M	-150.35M	-136.72M	-109.28M	92.03M
Operating Cash Flow	-163.58M	-150.05M	-133.91M	-108.82M	92.61M
Investing Cash Flow	-138.00K	-298.00K	-2.77M	-464.00K	-575.00K
Financing Cash Flow	-139.00K	1.55M	45.10M	241.46M	190.33M

Prothena Technical Analysis

• Technical Analysis Sentiment: Negative
• Last Price: 9.21
• 50DMA: Positive
• 100DMA: Negative
• 200DMA: Positive
• MACD: Negative
• RSI: Neutral
• STOCH: Neutral

Evaluating momentum and price trends is crucial in stock analysis to make informed investment decisions. For PRTA, the sentiment is Negative. The current price of 9.21 is below the 20-day moving average (MA) of 9.21, above the 50-day MA of 9.20, and above the 200-day MA of 8.56, indicating a bullish trend. The MACD of 0.12 indicates Negative momentum. The RSI at 50.31 is Neutral, neither overbought nor oversold. The STOCH value of 53.60 is Neutral, not indicating any strong overbought or oversold conditions. Overall, these indicators collectively point to a Negative sentiment for PRTA.

Prothena Peers Comparison

Name	Overall Rating	Market Cap	P/E Ratio	ROE	Dividend Yield	Revenue Growth	EPS Growth
ZVRA	62 Neutral	$585.94M	10.18	42.68%	―	240.47%	―
LXRX	60 Neutral	$716.02M	-8.29	-41.94%	―	1255.21%	74.58%
XOMA	55 Neutral	$326.67M	8.32	16.22%	―	118.02%	―
CRVS	55 Neutral	$1.28B	-39.78	-23.29%	―	―	79.27%
Sector *	51 Neutral	$7.86B	-0.30	-43.30%	2.27%	22.53%	-2.21%
PRTA	51 Neutral	$495.80M	-2.11	-67.63%	―	-91.16%	-112.24%
ALMS	50 Neutral	$3.09B	―	-75.52%	―	―	13.80%

Prothena Corporate Events

Prothena Announces $100 Million Share Repurchase Program

On February 27, 2026, Prothena announced that its board had authorized a share repurchase plan allowing the company to buy back up to $100 million of its ordinary shares, with the program running through December 31, 2026 and able to be suspended or discontinued at any time. The company, which reported $308.4 million in cash, cash equivalents and restricted cash and no debt as of December 31, 2025, said repurchases will depend on market and business conditions and noted it expects to end 2026 with about $255 million in cash excluding any buybacks, while also highlighting potential milestone payments from partners Novo Nordisk and Bristol Myers Squibb that could further bolster its financial position and capital allocation flexibility.

The repurchase authorization underscores Prothena’s confidence in its balance sheet and late-stage pipeline, signaling to investors that it sees value in its equity while retaining discretion over if and when to execute buybacks. For stakeholders, the plan introduces the possibility of enhanced shareholder returns and reduced share count over time, without constraining the company’s ability to fund ongoing clinical development in neurodegenerative and amyloid diseases or respond to changing market dynamics.

The most recent analyst rating on (PRTA) stock is a Buy with a $30.00 price target. To see the full list of analyst forecasts on Prothena stock, see the PRTA Stock Forecast page.