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Prothena Corporation plc PRTA

Healthcare — Biotechnology
Insider Buys (last 12m)
Insider Buys alert about insiders buying in the last 12 month

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Insider Decisions

Total buys
4.12
Total sells
0.14
in millions of $
Nov 25 Feb 26 May 26 Aug 26
Buy — — — — — — — 1 4 — 2 1
Sell — — — — — — — — — 2 — —
Insider Ownership
14.28%

Capital & Financial Ratios

Market Cap
434.31
Revenue
54.53
Net Income
(43.99)
Free Cash Flow
(60.80)
Net Debt
(288.19)
Current Ratio
25.05
Debt/Equity
0.00
P/E ratio
0.00
P/S ratio
8.20
P/B ratio
1.56
Past 5Y EPS Growth
(3.15%)
This Y EPS Growth
102.43%
Next Y EPS Growth
(943.94%)
Next 5Y EPS Growth
61.68%
in millions of $

Dividends

Payout Ratio
0.00
Annual Dividend Rate
—
Annual Dividend Yield
—
total individual payouts
2025 ‡‡‡
2024 ‡‡‡
2023 ‡‡‡
2022 ‡‡‡
2021 ‡‡‡
2020 ‡‡‡
2019 ‡‡‡
2017 ‡‡‡
predictions in italic, special payouts not included in total or ratios

Assets vs Liabilities

2023 2024 2025 Q'26
Cash 620.18 471.39 307.53 288.19
Receivables 5.16 — — —
Inventory — — — —
Other — — — —
639.28 485.41 315.19 292.01
2023 2024 2025 Q'26
Payables 25.39 7.77 5.88 1.94
ST’ Debt — — — —
Other 15.66 15.84 25.09 5.59
56.89 48.50 40.84 11.66
in millions of $

Compound Annual Growth

10y 5y 3y
Sales ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡
Cash Flow ‡‡‡ ‡‡‡ ‡‡‡
Earnings ‡‡‡ ‡‡‡ ‡‡‡
Book Value ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡

Revenue

Mar Jun Sep Dec Year
’26 51.08 1.01 — —
—
’25 2.83 4.42 2.42 0.02
9.68
’24 0.05 132.01 0.97 2.12
135.16
’23 2.17 4.02 84.87 0.32
91.37
’22 1.15 1.31 1.52 49.92
53.91
’21 0.16 60.07 139.17 1.17
200.58
’20 0.14 0.20 0.16 0.36
0.85
in millions of $

Operating Cash Flow

Mar Jun Sep Dec Year
’26 28.88 (25.05) — —
—
’25 (53.36) (46.34) (40.56) (23.31)
(163.58)
’24 (73.05) 15.96 (45.19) (47.77)
(150.05)
’23 (47.46) (44.93) 9.52 (51.04)
(133.91)
’22 (37.41) (35.26) (31.17) (4.98)
(108.82)
’21 (33.67) 36.62 112.11 (22.46)
92.61
’20 (23.17) (18.70) (19.40) (19.09)
(80.36)
in millions of $

Free Cash Flow

Mar Jun Sep Dec Year
’26 28.88 (25.70) — —
—
’25 (53.40) (46.43) (40.57) (23.31)
(163.72)
’24 (73.15) 15.82 (45.19) (47.81)
(150.35)
’23 (47.51) (45.70) 9.08 (52.55)
(136.68)
’22 (37.44) (35.42) (31.30) (5.13)
(109.28)
’21 (33.71) 36.62 111.90 (22.78)
92.03
’20 (23.19) (18.74) (19.48) (19.14)
(80.56)
in millions of $

EPS

Mar Jun Sep Dec Year
’26 0.60 (0.36) — —
—
’25 (1.12) (2.34) (0.68) (0.40)
(4.53)
’24 (1.34) 1.22 (1.10) (1.08)
(2.27)
’23 (0.89) (1.03) 0.38 (1.26)
(2.76)
’22 (0.78) (0.88) (0.97) 0.12
(2.47)
’21 (0.91) 0.58 2.13 (0.71)
1.38
’20 (0.59) (0.66) (0.77) (0.77)
(2.78)

Target Price Range

High
‡‡‡‡‡
‡‡‡‡
Average
‡‡‡‡‡
‡‡‡‡
Low
‡‡‡‡‡
‡‡‡

Recommendation Rating

2.2
1
Buy
2
3
Hold
4
5
Sell
2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028
‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡ ‡‡‡‡ ‡‡‡ ‡‡‡‡‡ 21.06 28.51 11.70 4.32 — — —
Low Price
‡‡‡‡‡ ‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ 66.47 79.65 41.55 16.67 — — —
High Price
‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡ ‡‡‡‡ ‡‡‡‡ ‡‡‡‡ 127 173 163 67 — — —
Employees
‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ 0.42 0.53 0.83 0.14 — — —
Revenue/Emp
‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ 53.91 91.37 135.16 9.68 ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡
Revenue
‡‡‡ ‡‡‡ ‡‡‡ ‡‡‡ ‡‡‡ ‡‡‡ 100.00% 100.00% 100.00% 100.00% — — —
Gross Margin
‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ (125.60) (160.48) (128.93) (200.83) — — —
EBT
‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ (233.01%) (175.64%) (95.39%) (2,073.82%) ‡‡‡ ‡‡‡ ‡‡‡
EBT Margin
‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ (116.95) (147.03) (122.31) (244.09) ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡
Net Income
‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ 6.74 8.41 3.59 3.70 — — —
Depreciation
‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ 1.14 1.72 2.51 0.18 ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡
Revenue/Sh
‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡ (2.47) (2.76) (2.27) (4.53) ‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡
Earnings/Sh
‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ (2.30) (2.52) (2.79) (3.04) ‡‡‡‡‡ — —
Cash Flow/Sh
‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ (0.01) (0.05) (0.01) 0.00 ‡‡‡ ‡‡‡ ‡‡‡
Capex/Sh
‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ (2.31) (2.57) (2.80) (3.04) — — —
Free CF/Sh
‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ 13.13 10.55 9.06 5.21 ‡‡‡‡ — —
Book Value/Sh
‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ 47.37 53.22 53.77 53.83 ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡
Shares
‡‡‡ ‡‡‡ ‡‡‡ ‡‡‡ ‡‡‡ ‡‡‡‡‡ 0.00 0.00 0.00 0.00 ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡
PE Ratio
‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ 47.01 22.45 5.51 53.08 ‡‡‡ ‡‡‡ ‡‡‡
PS Ratio
‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ 4.07 3.65 1.53 1.83 ‡‡‡ ‡‡‡ ‡‡‡
PB Ratio
‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ 33.98 15.78 2.10 22.44 ‡‡‡ ‡‡‡‡ ‡‡‡‡
EV/Sales
‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ (16.76) (10.55) (1.89) (1.33) — — —
EV/FCF
‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ (108.82) (133.91) (150.05) (163.58) ‡‡‡ ‡‡‡ ‡‡‡
Op' Cash Flow
‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ (0.46) (2.77) (0.30) (0.14) ‡‡‡‡‡ ‡‡‡‡‡ —
Capex
‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ (109.28) (136.68) (150.35) (163.72) ‡‡‡‡‡ — —
FCF
‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ 668.95 582.39 436.91 274.35 — — —
Working Cap'
— — — ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ 6.47 — — — — — —
Total Debt
‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ (703.93) (620.18) (471.39) (307.53) — — —
Net Debt
‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ 622.04 561.37 486.93 280.47 — — —
Sh' Equity
‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ (17.11%) (20.22%) (19.67%) (55.86%) — — —
ROA
‡‡‡ ‡‡‡ ‡‡‡ ‡‡‡ ‡‡‡ ‡‡‡ 0.00% 0.00% (621.71%) 0.00% — — —
ROIC
‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ ‡‡‡‡‡ (21.50%) (24.85%) (23.34%) (63.62%) — — —
ROE
predictions in italic, sparklines do not include predictions

Analyst Commentary (Summary)

Prothena Corporation (PRTA), a clinical-stage biotech targeting misfolded protein diseases like amyloidosis and Alzheimer’s, trades at depressed levels near $9, far below Wall Street’s mean price target implying 106% upside (highs at 302%). Yet, fundamentals scream caution: revenue swings wildly from milestone payments—peaking at $135M in 2024 before a forecasted 93% plunge to $10M in 2025—masking no sustainable sales, brutal cash burn (-$151M operating cash flow in 2024), and dilution via 56% share increase since 2016. Profitability is illusory, with net losses ballooning to -$122M in 2024 and projected -$251M in 2025, eroding ROE to -23%.

A fortress-like balance sheet offers temporary relief, with $471M net cash funding the burn, but insider actions blare alarms—a 10% owner dumped 6.28M shares for $51M in May 2025 amid silence on buys. Pipeline catalysts like ALZ-801 Phase 2 data and birtamimab trial hopes drive analyst optimism for a 2026 revenue rebound to $118M, but history’s trial flops (e.g., AFFIRM-AL Phase 3 miss) and biotech graveyard risks suggest a high-wire bet.

Valuation looks cheap at 1.5x PB and 5.5x PS, tracing revenue highs/lows faithfully, but EV/Sales spikes to 48x in 2025 price in miracles. Is this a contrarian dip or dilution trap? Dive into the full analysis for the quantitative breakdown and 2026 catalysts that could moon or crater shares.

Read full commentary →

Prothena Corporation plc (PRTA) Latest News

News by impact score

Fine-tune

19 Aug

3 , 12:32 PM
Jupiter Neurosciences advances offer new hope for Parkinson’s Disease treatment, positioning the company as a potential contender in the space where Prothena operates. Competitor progress in Parkinson’s may moderately affect Prothena’s positioning without immediate fundamental shifts.

7 Aug

3 , 1:41 PM
Prothena Corporation plc posted a narrower-than-expected Q2 loss while pipeline progress remains in focus. Narrower Q2 loss combined with pipeline updates signals moderate effects on financial outlook and development trajectory.

6 Aug

3 , 7:10 PM
Prothena reported a Q2 net loss and missed revenue estimates. Q2 loss and revenue miss may pressure near-term stock price and sentiment.

3 , 4:05 PM
Prothena Corporation plc released second quarter 2026 financial results and business highlights. Quarterly results deliver performance updates that can shift near-term investor sentiment without altering long-term company trajectory.

11 May

4 Simply Wall St., 9:17 AM
Prothena Corporation plc beat analyst earnings forecasts, prompting analysts to update their models with more optimistic projections. Beating earnings forecasts and triggering analyst model updates indicates strong financial performance that could significantly enhance investor sentiment and stock trajectory.

8 May

4 Zacks, 10:36 AM
Prothena Corporation plc (PRTA) reported first-quarter earnings with revenues surging due to a milestone payment. Revenue surge from milestone payment highlights pipeline advancement and bolsters financial position for biotech growth.

7 May

3 Business Wire, 4:05 PM
Prothena Corporation plc reported first quarter 2026 financial results and business highlights. Quarterly financial results and business highlights moderately influence financial performance and market sentiment.

27 Apr

4 Business Wire, 4:05 PM
Prothena announces Novo Nordisk obtained U.S. FDA Fast Track Designation for Coramitug (PRX004) in ATTR amyloidosis with cardiomyopathy. FDA Fast Track Designation accelerates clinical development and approval pathway for Prothena's partnered amyloidosis drug candidate.

1 Apr

4 , 11:04 AM
AstraZeneca released data from its Hypophosphatasia program on Efzimfotase Alfa, involving Prothena Corporation plc (PRTA). Partner AstraZeneca posting clinical data on Efzimfotase Alfa marks a major milestone for Prothena's pipeline, likely boosting investor sentiment and stock performance.

4 Zacks, 11:04 AM
AstraZeneca posted data from its Hypophosphatasia program on Efzimfotase Alfa. Clinical data release from a biotech program directly influences PRTA's pipeline prospects and investor sentiment.

26 Mar

4 Zacks, 9:55 AM
Wall Street analysts forecast Prothena Corporation plc (PRTA) stock could surge 120.19%, driven by strong buy ratings and elevated price targets reflecting optimism on pipeline progress and clinical milestones. Analyst consensus targets 120.19% upside for PRTA, signaling major potential boost to investor sentiment and market performance.

21 Mar

4 Business Wire, 4:05 PM
Prothena Corporation plc partners presented data at AD/PD™ 2026 supporting next-generation treatments for Parkinson’s and Alzheimer’s Disease. Presentation of supportive clinical data for next-generation treatments targeting Parkinson’s and Alzheimer’s at a premier conference validates pipeline advancements and likely enhances investor sentiment.

9 Mar

4 Business Wire, 4:05 PM
Prothena Corporation plc achieved a $50 million clinical milestone payment from Novo Nordisk for progress in the ongoing Phase 3 trial of coramitug (formerly PRX004) for ATTR amyloidosis with cardiomyopathy. $50 million milestone payment delivers non-dilutive cash, validates Phase 3 progress in high-value ATTR-CM indication, and strengthens financial runway amid biotech partnership.

3 Mar

4 Zacks, 9:55 AM
Wall Street analysts predict Prothena Corporation plc (PRTA) stock could rally 118.09% based on consensus price targets, with detailed trading strategies including buy recommendations and risk assessments. Analysts' 118.09% upside target for PRTA signals major potential boost to investor sentiment and stock trajectory.

27 Feb

4 Business Wire, 4:15 PM
Prothena Corporation plc (PRTA) announces a share repurchase program authorizing the buyback of up to $100 million in common stock, signaling management's confidence in the company's future prospects. Prothena's $100 million share repurchase plan is a major strategic move that boosts investor confidence, supports stock price, and enhances shareholder value.

20 Feb

4 app.moby.co, 8:30 AM
Prothena Corporation plc released Q4 2025 earnings call summary detailing financial results, pipeline updates, and forward guidance. Q4 earnings call summary reveals financial performance and strategic updates that significantly shape investor sentiment and stock trajectory.

4 GuruFocus.com, 12:02 AM
Prothena Corporation plc (PRTA) highlighted strategic advancements and key financial updates in its Q4 2025 earnings call. Strategic advancements in Q4 2025 earnings call signal major shifts poised to alter PRTA's trajectory and investor sentiment.

3 Zacks, 11:27 AM
Prothena Corporation plc (PRTA) Q4 earnings met analyst estimates, with pipeline progress highlighted as a key focus for investors. Earnings meeting estimates offers short-term stability, while pipeline progress signals moderate advancements in core biotech operations.

19 Feb

4 www.marketbeat.com, 7:08 PM
Prothena Corporation plc (PRTA) released highlights from its Q4 earnings call, detailing financial results, pipeline updates on treatments for ATTR amyloidosis and AL amyloidosis, clinical trial progress, and 2024 guidance. Q4 earnings highlights disclose financial outcomes, clinical advancements, and forward guidance pivotal to stock trajectory and investor confidence.

4 Associated Press Finance, 4:34 PM
Prothena Corporation plc (PRTA) reported Q4 results, including key financial metrics like revenue, EPS, and outlook in its earnings snapshot. Q4 earnings snapshots directly impact stock performance through reported financials, guidance, and market reactions.

4 Business Wire, 4:05 PM
Prothena Corporation plc (PRTA) reported fourth quarter and full year 2025 financial results, provided financial guidance, and highlighted key business developments. Financial results and forward guidance represent major updates that can significantly shift investor sentiment and stock trajectory.

3 Zacks, 5:35 PM
Prothena Corporation plc (PRTA) reported a Q4 net loss and revenue that missed analyst estimates. Q4 loss and revenue shortfall highlight weaker financial results, likely pressuring short-term stock performance and investor sentiment.

16 Feb

4 Zacks, 9:54 AM
Prothena Corporation plc (PRTA) stock plummeted 36.8% year-over-year, sparking uncertainty about the company's future performance and prospects. PRTA's 36.8% year-over-year stock decline represents a major hit to market performance and investor sentiment with potential to alter trajectory.

13 Feb

3 Zacks, 11:40 AM
Prothena Corporation plc (PRTA) is being compared to FTRE in terms of value investment potential. The analysis focuses on financial metrics, growth prospects, and market positioning of both companies. Investors are encouraged to consider various factors such as earnings, revenue growth, and market trends to determine which stock may offer better value. The comparison aims to provide insights for potential investors looking to make informed decisions in the biotech sector. The comparison of PRTA with FTRE highlights relevant financial metrics and market positioning that could moderately influence investor sentiment and decision-making.

21 Jan

4 Zacks, 12:00 PM
Prothena Corporation plc (PRTA) has received a rating upgrade to 'Buy' from analysts, reflecting positive sentiment regarding its future prospects. The upgrade is attributed to recent developments in the company's pipeline and overall market conditions, which are expected to enhance investor confidence. This shift in rating may lead to increased interest from investors and potentially drive stock performance upward. The rating upgrade indicates significant positive sentiment and potential for improved market performance.

20 Jan

4 Simply Wall St., 12:07 AM
Prothena Corporation plc has received a new price target and formed strategic partnerships that are expected to enhance its market position and growth potential. These developments are seen as pivotal in reshaping the company's narrative and could lead to significant advancements in its product pipeline and overall financial performance. New partnerships and a revised price target are likely to significantly impact Prothena's future growth and market performance.

5 Jan

4 Simply Wall St., 4:08 PM
Prothena Corporation plc (PRTA) is experiencing a shift in its narrative and price target outlook due to its partnered pipelines. Collaborations with other companies are enhancing its research and development capabilities, potentially leading to significant advancements in its therapeutic offerings. These partnerships are expected to influence investor sentiment positively and may result in a reevaluation of the company's market position and future growth prospects. Partnerships are likely to lead to significant advancements in product development and market positioning.

2 Jan

4 Simply Wall St., 12:03 PM
Prothena Corporation plc is positioned to drive business growth through its innovative pipeline and strategic initiatives. The company is focusing on advancing its clinical programs and expanding its market presence, which could enhance its competitive edge in the biotechnology sector. With a strong financial foundation, Prothena is well-equipped to invest in research and development, potentially leading to significant advancements in treatment options for neurodegenerative diseases. Prothena's strategic initiatives and focus on innovation are likely to significantly impact its future performance and market positioning.

12 Dec

3 Business Wire, 4:05 PM
Prothena Corporation plc announced updates to its Board of Directors, including the appointment of new members and changes in leadership roles. These updates aim to enhance the company's strategic direction and governance as it continues to advance its pipeline of therapeutic candidates. Board updates can influence governance and strategic direction, impacting overall company performance.

6 Dec

4 Simply Wall St., 11:07 AM
Prothena Corporation plc has updated its pipeline and valuation, leading to a shift in market perception. The company is advancing its clinical programs, particularly in neurodegenerative diseases, which has garnered investor interest. Analysts are reassessing the company's potential based on these developments, suggesting a more favorable outlook for Prothena's future performance. The updates on the pipeline and valuation are likely to significantly influence investor sentiment and the company's strategic direction.
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