ValueScreener

ValueScreener company report

Prothena Corporation plc (PRTA)

NASDAQ / Healthcare / Biotechnology

Share price

8.50 USD Market dataClose of Oct 15, 2026

Market capitalisation

436.4M USD Market dataClose of Oct 15, 2026
Market data
Oct 15, 2026
Filed accounts
FY2025, filed Feb 27, 2026
Ratios computed
Oct 15, 2026
Filed years
14, FY2011 to FY2025
Four kinds of sourceSEC filingCompany statementMarket dataComputedWhat each means
SEC filingFiled with the SEC
Read from a statement the company filed with the SEC, with the form, fiscal year, filing date and accession beside it.
Company statementCompany statement
What the company says about itself in a filing: an 8-K item, the auditor, its own segment names.
Market dataMarket data
Prices, market value and what analysts publish, with the date they are as of.
ComputedComputed by ValueScreener
Worked out by us from the other three, with the inputs and the formula one press away. A score is a research output, not a rating or a recommendation.
Reading

1 of 10

Overview

What the business is, what it costs, and how it reads on four questions.

Market dataSEC filingComputed

Four questions, at a glance

Quality

Return on equity

-87.0% Computed

From the FY2025 filing

Read quality

Valuation

Price to book

1.63x Computed

FY2025 accounts, priced at the latest close

Read valuation

Cash generation

Free cash flow yield

-35.8% Computed

FY2025 accounts, priced at the latest close

Read cash generation

Revenue and net income, as filed

FY2016 Revenue: 1.1M USDFY2016 Net income: -160.1M USDFY2017 Revenue: 27.5M USDFY2017 Net income: -153.2M USDFY2018 Revenue: 955.0K USDFY2018 Net income: -155.6M USDFY2019 Revenue: 814.0K USDFY2019 Net income: -77.7M USDFY2020 Revenue: 853.0K USDFY2020 Net income: -111.1M USDFY2021 Revenue: 200.6M USDFY2021 Net income: 67.0M USDFY2022 Revenue: 53.9M USDFY2022 Net income: -116.9M USDFY2023 Revenue: 91.4M USDFY2023 Net income: -147.0M USDFY2024 Revenue: 135.2M USDFY2024 Net income: -122.3M USDFY2025 Revenue: 9.7M USDFY2025 Net income: -244.1M USD
Revenue Net income10 filed fiscal years, from the annual reports; the table in Filings names each document.
Named tests met
0 of 30 Which tests
The business, and the score behind its five axes

The reading, in brief

Is it good

Return on equity was -87.0% in FY2025, in the band labelled "Likely below the cost of equity" (below 8.0%), on lines anchored on Damodaran's cost-of-capital data, suggesting returns on shareholders' money below the usual cost of equity.

Today, against the Biotechnology industry (494 companies), -87.0% sits at the 39th percentile; the middle half of that group runs from -146.9% to -28.9%.

Is it safe

Current ratio was 7.72 in FY2025, in the band labelled "At or above Graham's requirement" (2.00 and above), on lines anchored on Graham's defensive-investor criteria, suggesting short-term assets well above short-term obligations.

Today, against the Biotechnology industry (556 companies), 7.72 sits at the 68th percentile; the middle half of that group runs from 2.39 to 9.18.

Year by year against peers
Whether Prothena Corporation plc's return on equity stayed above the median of the Biotechnology industry, year by year. (FY2021 to FY2025, 5 fiscal years of Prothena Corporation plc with a comparable figure)
The direction
Which way Prothena Corporation plc's return on equity has moved, and how steadily. (FY2016 to FY2025, 10 filed years of Prothena Corporation plc)
What could explain it
What in Prothena Corporation plc's filed statements could explain the movements. (3 readings drawn from the statement lines Prothena Corporation plc filed)
What to check next
What to check next on Prothena Corporation plc, and where in its filings. (3 questions for Prothena Corporation plc)
In one paragraph
One paragraph on Prothena Corporation plc's returns, cash, balance sheet and price. (7 of sixteen figures read for Prothena Corporation plc)

These are PRTA’s filed figures. The research desk says what they mean, against peers and its own years, with what to check next.

Research PRTAPart of Serious. New accounts start with 30 days of Professional, free, no card.

2 of 10

What changed

The newest filing, what it moved, and when the next one is due.

SEC filingCompany statement

The newest accounts on file are the FY2025 annual report: 10-K, filed Feb 27, 2026, accession 0001559053-26-000008.

3 of 10

Quality

The returns the business earns on its capital, and the margins behind them.

SEC filingComputed

Prothena Corporation plc: returns on capital and margins, each with its source
FigureValue, source and document
Return on invested capital, after tax
Why n/a

The filed borrowings do not add up to a total we can stand behind: the filer's own liability subtotals leave room for debt we did not read.

n/a ComputedFY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008
Return on equity-87.0% ComputedFY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008
Return on capital employed, pre-tax-75.1% ComputedFY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008
Return on assets-74.7% ComputedFY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008
Gross margin
Why n/a

Our archived statements for this filer carry no gross profit line, so there is nothing to compute a gross margin from and trace back to source. That may be because the filer presents no cost of revenue, or because we have not captured the concept. We do not guess which.

n/a ComputedFY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008
Operating margin-2216.4% ComputedFY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008
Net margin-2520.6% ComputedFY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008
PRTA -2520.6%
SLN -15851.9%CBIO -1419.6%ENTX -27235.7%PROK -7725.2%STTK -4880.9%
-27235.7%-1419.6%
Net margin: PRTA against the 5 companies named under Valuation context, each as filed for its own latest year. Placement only: no average is drawn.

4 of 10

Financial strength

What it owes against what it owns, and whether it can meet what falls due.

SEC filingComputedCompany statement

Prothena Corporation plc: leverage, liquidity and distress, each with its source
FigureValue, source and document
Debt to equity
Why n/a

The filed borrowings do not add up to a total we can stand behind: the filer's own liability subtotals leave room for debt we did not read.

n/a ComputedFY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008
Current ratio7.72 ComputedFY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008
Quick ratio7.72 ComputedFY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008
Interest coverage
Why n/a

No interest expense is filed for this year, so coverage is not computed.

n/a ComputedFY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008
Altman Z-score-0.97 ComputedClose of Oct 15, 2026 · FY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008
Net debt
Why n/a

The FY2025 balance sheet carries no net debt we could read.

n/a ComputedFY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008
Total assets 326.8MTotal liabilities 46.3MShareholders' equity 280.5MOwnsOwes, and equity
Total assets Total liabilities Shareholders’ equity
The balance sheet, line by line

Financial health

What Prothena Corporation plc owned and owed at the end of fiscal 2025, from the balance sheet it filed (10-K, filed Feb 27, 2026, 0001559053-26-000008).

Prothena Corporation plc: balance sheet position
Total assets326.8M FiledFY2025 10-K, filed Feb 27, 2026
Total liabilities46.3M FiledFY2025 10-K, filed Feb 27, 2026
Shareholders' equity280.5M FiledFY2025 10-K, filed Feb 27, 2026
Cash307.5M FiledFY2025 10-K, filed Feb 27, 2026
Total debtn/a FiledFY2025 10-K, filed Feb 27, 2026
Net debtn/a
Current ratio7.72
Debt to equityn/a
  • Debt to equity: FY2025: The filed borrowings do not add up to a total we can stand behind: the filer's own liability subtotals leave room for debt we did not read.
  • Interest cover: FY2025: No interest expense is filed for this year, so coverage is not computed.

Read from the filed balance sheet for each year, with the income statement of the same year supplying operating profit where a ratio needs it. Nothing here is a view on whether this company is sound.

5 of 10

Valuation context

What the market charges for it, against its own record and companies like it.

Market dataSEC filingComputed

Prothena Corporation plc: what the market charges, each with its source
FigureValue, source and document
Price to earnings
Why n/m

Earnings are zero or negative, so a price to earnings multiple is not meaningful. A negative P/E is not a cheap company and a large positive one from a near-zero denominator is not an expensive one.

n/m ComputedClose of Oct 15, 2026 · FY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008
P/E on trailing twelve months1196.80x ComputedClose of Oct 15, 2026 · Trailing four quarters, each as known on the day; the quarterly filings are listed under Filings
Price to book1.63x ComputedClose of Oct 15, 2026 · FY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008
Price to sales47.25x ComputedClose of Oct 15, 2026 · FY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008
Enterprise value to EBIT
Why n/a

We do not hold this figure for this company, so there is nothing to show.

n/a ComputedClose of Oct 15, 2026 · FY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008
Enterprise value to EBITDA
Why n/m

EBITDA is zero or negative, so a multiple of it is not meaningful.

n/m ComputedClose of Oct 15, 2026 · FY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008
Price to earnings over growth
Why n/m

Earnings are zero or negative, so a price to earnings multiple is not meaningful. A negative P/E is not a cheap company and a large positive one from a near-zero denominator is not an expensive one.

n/m ComputedClose of Oct 15, 2026 · FY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008
Diluted earnings per share-4.53 USD FiledFY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008
Graham number
Why n/m

Earnings are zero or negative, so a price to earnings multiple is not meaningful. A negative P/E is not a cheap company and a large positive one from a near-zero denominator is not an expensive one.

n/m ComputedFY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008

We publish no fair value or price target of our own. Value PRTA on your own assumptions in the DCF workbench, starting from the filed figures.

Its own record, and companies like it

Valuation

What the market charges for Prothena Corporation plc today, and the multiples it has carried. No value of ours: the figures are the filings’ and the market’s.

Prothena Corporation plc: valuation
Share price8.50 USD
Market capitalisation436.4M USD
Enterprise value to EBITDAn/m
Graham numbern/m
Diluted earnings per share, FY2025-4.53 USD

Price to earnings on trailing twelve months, a different basis from the fiscal-year P/E above, since Oct 3, 2016: low 15.05x, median 33.38x, high 1269.00x, latest 1196.80x. 251 trading days with a meaningful ratio, 2,272 more on a loss and left out. Each close over the trailing twelve months of earnings as known that day: a quarter counts from the day it was filed.

Companies like Prothena Corporation plc

  1. Silence Therapeutics plc (SLN)Market cap 441.6M USD
  2. Crescent Biopharma, Inc. (CBIO)Market cap 463.6M USD
  3. Entera Bio Ltd. (ENTX)Market cap 481.5M USD
  4. ProKidney Corp. (PROK)Market cap 489.2M USD
  5. Shattuck Labs, Inc. (STTK)Market cap 555.0M USD

Same industry (Biotechnology) and size band (Small, 300M to 2B), nearest in market value, net margin and current ratio. Each of those counts equally, by how many of the companies considered sit between the two on it. Closest first: the order is likeness and nothing else.

6 of 10

Cash generation

Whether profit arrives as cash, and what is paid back to shareholders.

SEC filingComputed

Prothena Corporation plc: cash generation and what is paid out, each with its source
FigureValue, source and document
Free cash flow yield-35.8% ComputedClose of Oct 15, 2026 · FY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008
Free cash flow-163.7M USD ComputedFY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008
Free cash flow margin-1690.6% ComputedFY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008
Dividend yield
Why n/a

We do not hold this figure for this company, so there is nothing to show.

n/a ComputedClose of Oct 15, 2026 · FY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008
Payout ratio
Why n/a

We do not hold this figure for this company, so there is nothing to show.

n/a ComputedFY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008
FY2016 Free cash flow: -132.9M USDFY2016 Net income: -160.1M USDFY2017 Free cash flow: -134.8M USDFY2017 Net income: -153.2M USDFY2018 Free cash flow: -30.0M USDFY2018 Net income: -155.6M USDFY2019 Free cash flow: -53.5M USDFY2019 Net income: -77.7M USDFY2020 Free cash flow: -80.6M USDFY2020 Net income: -111.1M USDFY2021 Free cash flow: 92.0M USDFY2021 Net income: 67.0M USDFY2022 Free cash flow: -109.3M USDFY2022 Net income: -116.9M USDFY2023 Free cash flow: -136.7M USDFY2023 Net income: -147.0M USDFY2024 Free cash flow: -150.3M USDFY2024 Net income: -122.3M USDFY2025 Free cash flow: -163.7M USDFY2025 Net income: -244.1M USD
Free cash flow Net incomeProfit that arrives as cash stands level with net income; a gap year after year is worth reading about.

7 of 10

Filings

Every figure, the year it is for and the document it was read from.

SEC filingMarket data

The filed figures

Computed from the accounts this company filed with the SEC and, in a ratio with a price in it, the last close, dated on this page. Every filed figure below carries the fiscal year and the filing date its accounts were read from, and every blank carries the reason it is blank. Nothing here is a view on this company.

Prothena Corporation plc: the eight ratios, with the fiscal year and filing date behind each.
FigureValueYearAs of
n/mFY2025Oct 15, 2026
n/m Not meaningful for this company, such as a P/E on negative earnings or a bank's EV/EBIT.
1.63xFY2025Oct 15, 2026
n/aFY2025Oct 15, 2026
n/a Operating profit is zero or negative, so there is no profit for a buyer's price to be a multiple of.
-35.8%FY2025Oct 15, 2026
n/aFY2025Feb 27, 2026
n/a The filed borrowings do not add up to a total we can stand behind: the filer's own liability subtotals leave room for debt we did not read.
n/aFY2025Oct 15, 2026
n/a The filed cash flow statement reports no dividend paid at all. That is not the same as a filed zero, and we will not read it as one.
n/aFY2025Feb 27, 2026
n/a The filed borrowings do not add up to a total we can stand behind: the filer's own liability subtotals leave room for debt we did not read.
7.72FY2025Feb 27, 2026
47.25xFY2025Oct 15, 2026
n/mFY2025Oct 15, 2026
n/m Not meaningful for this company, such as a P/E on negative earnings or a bank's EV/EBIT.
-0.97FY2025Oct 15, 2026
-5.71FY2025Feb 27, 2026
1/9FY2025Feb 27, 2026

The figures are computed from the accounts for fiscal 2025, the newest full year on file. 14 filed fiscal years on record, FY2011 to FY2025, from SEC EDGAR. Prices as of Oct 15, 2026. Ratios recomputed Oct 15, 2026. Two facts, because a recompute is not a fresh quote.

The year and the filing date name the statement each figure’s accounts are read from, and they stand even where the figure itself could not be computed: the line beneath a blank says what that statement did not carry. A figure’s name opens its formula and the filings behind it; a statement that names no SEC filing has no filing date, and reads n/a.

Ten years of filed figures, year by year

Ten years of filed figures

10 filed fiscal years, FY2016 to FY2025, read from the annual reports Prothena Corporation plc filed with the SEC. Each year names its filing. Amounts in USD, as filed.

Prothena Corporation plc: revenue, earnings, free cash flow and returns, by fiscal year, with the filing each year was read from
YearRevenueOperating incomeNet incomeEPS, dilutedFree cash flowOperating marginReturn on equityFiling
FY20259.7M-214.6M-244.1M-4.53-163.7M-2216.4%-87.0%10-K, Feb 27, 20260001559053-26-000008
FY2024135.2M-154.6M-122.3M-2.27-150.3M-114.4%-25.1%10-K, Feb 27, 20250001559053-25-000009
FY202391.4M-191.0M-147.0M-2.76-136.7M-209.1%-26.2%10-K, Feb 22, 20240001559053-24-000008
FY202253.9M-131.6M-116.9M-2.47-109.3M-244.1%-18.8%10-K, Feb 28, 20230001559053-23-000005
FY2021200.6M72.0M67.0M1.3892.0M35.9%14.4%10-K, Feb 25, 20220001559053-22-000008
FY2020853.0K-112.7M-111.1M-2.78-80.6M-13216.2%-60.4%10-K, Feb 26, 20210001559053-21-000008
FY2019814.0K-85.7M-77.7M-1.95-53.5M-10527.9%-28.5%10-K, Mar 3, 20200001559053-20-000005
FY2018955.0K-158.9M-155.6M-3.93-30.0M-16634.0%-48.2%10-K, Mar 15, 20190001559053-19-000007
FY201727.5M-155.3M-153.2M-4.07-134.8M-564.2%-37.6%10-K, Feb 26, 20180001559053-18-000008
FY20161.1M-159.5M-160.1M-4.66-132.9M-15121.8%-43.8%10-K, Feb 27, 20170001559053-17-000005
  • Revenue, compound annual growth FY2016 to FY2025: 27.9%
  • Earnings: Earnings was not positive in both 2016 and 2025, so a compound rate across the window is not defined. Both figures are in the table.
  • Earnings per share: Earnings per share was not positive in both 2016 and 2025, so a compound rate across the window is not defined. Both figures are in the table.
  • Free cash flow: Free cash flow was not positive in both 2016 and 2025, so a compound rate across the window is not defined. Both figures are in the table.

Every figure in this section is a line of a filed annual statement or a ratio of two of them. Nothing here is estimated or smoothed. Earnings per share filed before a share split are put on today's share count, and say so. Nothing here is a verdict on the company.

8 of 10

Risks and guardrails

The accounting screens, the published tests, and the lines you can set to be told.

ComputedCompany statement

Prothena Corporation plc: accounting screens and published tests, each with its source
FigureValue, source and document
Beneish M-score-5.71 ComputedFY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008
Piotroski F-score1/9 ComputedFY2025 10-K, filed Feb 27, 2026, 0001559053-26-000008
Named tests met0 of 30 Computed
Beta0.89 ComputedClose of Oct 15, 2026

The named tests

Of 30 tests value investors published: 0 met, 23 not met, 7 we could not complete. Counts, never a score: a single figure would have to decide that meeting one investor’s criteria and meeting another’s are worth the same.

Which tests, by name(all 30)
Meets
None of the named tests.
Does not
Defensive investor (Benjamin Graham); Deep value; Large cap, low P/E; High F-score, low P/B (Joseph Piotroski); Three forensic scores; High returns and growth; Gross margin, turnover (Robert Novy-Marx); EV/EBITDA and coverage; High yield, low payout; Dividends and buybacks; Low beta, profitable; Near the 52-week low; Z-score and coverage (Edward Altman); Two thirds of NCAV (Benjamin Graham); High returns, low debt; Owner earnings yield; High return on tangibles; Low P/S, rising earnings (James O'Shaughnessy); Book or below, low debt (Walter Schloss); Tangible book or below; Cash-flow yield and ROIC; Clean books, high ROIC; Cheapest quarter on P/B (David Dreman)
Not measured
Earnings yield and ROIC (Joel Greenblatt); Low PEG, low debt (Peter Lynch); ROIC at or above WACC; P/E times P/B (Benjamin Graham); Cash-covered dividend; Cheapest quarter on P/E (David Dreman); Low P/E, growth, yield (John Neff). A test with a figure we could not read is incomplete, never met and never failed.
Figures we could not read(15)
  • Debt to Equity: The filed borrowings do not add up to a total we can stand behind: the filer's own liability subtotals leave room for debt we did not read.
  • P/E Ratio: Earnings are zero or negative, so a price to earnings multiple is not meaningful. A negative P/E is not a cheap company and a large positive one from a near-zero denominator is not an expensive one.
  • EV/EBIT: We do not hold this figure for this company, so there is nothing to show.
  • Return on Invested Capital: The filed borrowings do not add up to a total we can stand behind: the filer's own liability subtotals leave room for debt we did not read.
  • PEG Ratio: Earnings are zero or negative, so a price to earnings multiple is not meaningful. A negative P/E is not a cheap company and a large positive one from a near-zero denominator is not an expensive one.
  • Eps Growth 5Y: We do not hold this figure for this company, so there is nothing to show.
  • Gross Margin: Our archived statements for this filer carry no gross profit line, so there is nothing to compute a gross margin from and trace back to source. That may be because the filer presents no cost of revenue, or because we have not captured the concept. We do not guess which.
  • EV/EBITDA: EBITDA is zero or negative, so a multiple of it is not meaningful.
  • Interest Coverage: No interest expense is filed for this year, so coverage is not computed.
  • Dividend Yield: We do not hold this figure for this company, so there is nothing to show.
  • Payout Ratio: We do not hold this figure for this company, so there is nothing to show.
  • ROIC-WACC Spread: We do not hold this figure for this company, so there is nothing to show.
  • Price To Graham: Earnings are zero or negative, so a price to earnings multiple is not meaningful. A negative P/E is not a cheap company and a large positive one from a near-zero denominator is not an expensive one.
  • Dividend Coverage Ratio: We do not hold this figure for this company, so there is nothing to show.
  • Dividend Streak: We do not hold this figure for this company, so there is nothing to show.

9 of 10

Declared positions

Whether anybody here owns this company.

Positions declared by the founder: no holding in any company shown here, as of October 3, 2026.

10 of 10

Next step

What to do with what you have read.

A thesis is your reason for owning it, in your words, with the figures that must stay true. Checking those figures every night against the newest filed accounts, and telling you once when one breaks, is what the subscription adds.

More on this company

What this cannot tell you

  • 15 figures could not be read on this company, among them Debt to Equity, P/E Ratio, EV/EBIT. Each blank in the table above names the rest, with its reason. 7 named tests come back incomplete because of them, which is neither met nor missed.

And the one that is true of all of it: This is what the numbers say today. It cannot tell you the day one of them stops being true. Nothing here can, because the reasons are not written down.

Running this once is arithmetic on public documents and you are welcome to it. Writing down why you own each company, in your own words and with the numbers that have to stay true for it to hold, and then having those numbers re-checked every night against the newest filed accounts, and against the latest close where a rule watches a price, is Professional, the plan a new account starts on for 30 days, one trial per person. It writes to you the day one breaks, and stays quiet when nothing does. The check runs every night at 23:30 UTC. A filing is picked up the night after it is published.

No card. 30 free days, and nothing is charged unless you choose a plan.

Analyze your own portfolio

ValueScreener · valuescreener.ai · Computed from accounts filed with the SEC by this company, read from EDGAR, and from dated closing prices. On this page a filed figure opens into its formula, its inputs and the statement, fiscal year and filing date it was read from, and a price into the day of its close. A figure that cannot show that trail says so.

A computation on accounts filed with the SEC, not a recommendation and not advice. Past filings do not indicate future results. Risk disclaimer.

Once a week, what changed in the filings of US-listed companies, why it can matter to a thesis, and what deserves a closer review. Grounded in filings, not market noise.

Site map
  • Android app coming soon
  • iPhone app coming soon
ValueScreener

Discover companies, research each one to its filings, track what matters, and take your work into your own spreadsheet.

ValueScreener is a trading name of Oliva Real Estate Technologies LLC, a Delaware limited liability company. Legal notices: legal@valuescreener.ai. © 2026 Oliva Real Estate Technologies LLC. All rights reserved.

Risk disclaimer. This service is provided for research and education only. Nothing on it is investment advice, a recommendation, or an offer to buy or sell any security. Capital is at risk, and past performance does not indicate future results. Figures come from filed accounts and may be incomplete, delayed or later restated, so verify a number against the filing before you act on it.