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Prothena Corporation plc (PRTA)

Prothena Corporation plc at a glance — key fundamentals, SEC filings, insider buying and selling, and earnings dates.

Prothena Corporation plc (PRTA) is a Biotechnology company based in IE with a market capitalization of $528.8M. Revenue declined 92.8% year-over-year and free cash flow was negative at -$163.7M. This page tracks PRTA's SEC filings, insider buying and selling, earnings dates, and key fundamentals in one place.

IE · 163 employees · IPO Dec 18, 2012

Valuation

Valuation & price

$9.76 · as of May 17, 2026 · -15.2% vs 52w high

—

P/E ratio

Latest-FY diluted EPS

1.89

P/B ratio

Market cap ÷ book equity

—

Dividend yield

Price — last 12 months

$11.51$8.87$6.22Jul 25Dec 25Jul 26Jul 7, 25$6.29Jul 9, 25$6.58Jul 11, 25$6.40Jul 15, 25$6.22Jul 17, 25$6.47Jul 21, 25$6.29Jul 23, 25$6.76Jul 25, 25$6.68Jul 29, 25$6.93Jul 31, 25$6.87Aug 4, 25$6.94Aug 6, 25$7.92Aug 11, 25$7.67Aug 13, 25$8.05Aug 15, 25$8.25Aug 19, 25$8.52Aug 21, 25$8.56Aug 25, 25$8.38Aug 27, 25$8.56Aug 29, 25$8.20Sep 3, 25$8.39Sep 5, 25$8.55Sep 9, 25$8.34Sep 11, 25$8.43Sep 16, 25$8.16Sep 18, 25$8.18Sep 22, 25$8.29Sep 24, 25$9.32Sep 26, 25$9.41Sep 30, 25$9.76Oct 2, 25$9.99Oct 6, 25$9.86Oct 8, 25$10.35Oct 10, 25$10.05Oct 14, 25$10.12Oct 16, 25$10.09Oct 21, 25$10.22Oct 23, 25$9.75Oct 27, 25$10.37Oct 29, 25$10.65Oct 31, 25$10.75Nov 4, 25$10.26Nov 6, 25$10.08Nov 10, 25$10.53Nov 12, 25$10.85Nov 14, 25$9.93Nov 18, 25$10.36Nov 20, 25$10.05Nov 25, 25$10.50Nov 28, 25$10.75Dec 2, 25$10.35Dec 4, 25$11.16Dec 8, 25$10.73Dec 10, 25$9.87Dec 12, 25$10.36Dec 16, 25$9.75Dec 18, 25$9.38Dec 22, 25$9.68Dec 24, 25$9.69Dec 29, 25$9.48Jan 2, 26$9.20Jan 6, 26$8.97Jan 8, 26$9.05Jan 12, 26$8.91Jan 14, 26$9.20Jan 16, 26$9.35Jan 21, 26$9.68Jan 23, 26$10.00Jan 27, 26$9.73Jan 29, 26$9.06Feb 2, 26$8.91Feb 4, 26$8.89Feb 9, 26$8.86Feb 11, 26$8.93Feb 13, 26$8.96Feb 18, 26$9.09Feb 20, 26$9.02Feb 24, 26$8.97Feb 26, 26$8.64Mar 2, 26$9.40Mar 4, 26$9.86Mar 6, 26$9.59Mar 10, 26$9.77Mar 12, 26$9.31Mar 17, 26$9.00Mar 19, 26$8.54Mar 23, 26$8.82Mar 25, 26$9.31Mar 27, 26$9.26Mar 31, 26$9.72Apr 2, 26$9.86Apr 7, 26$10.36Apr 9, 26$10.58Apr 13, 26$10.31Apr 15, 26$10.82Apr 17, 26$10.90Apr 22, 26$10.72Apr 24, 26$10.75Apr 28, 26$11.51Apr 30, 26$11.06May 4, 26$10.79May 6, 26$11.18May 8, 26$10.73May 12, 26$9.43May 14, 26$9.86May 18, 26$9.59May 20, 26$9.35May 22, 26$9.83May 28, 26$9.98Jun 1, 26$9.59Jun 3, 26$8.92Jun 5, 26$8.79Jun 9, 26$8.47Jun 11, 26$8.26Jun 15, 26$8.15Jun 17, 26$8.49Jun 22, 26$9.15Jun 24, 26$9.40Jun 26, 26$10.02Jul 2, 26$9.91
$6.2252-week range$11.51
Loading valuation history…

Fundamentals

Key fundamentals

$528.8M

Market cap

-92.8%

Revenue growth (YoY)

61.8%

Gross margin

-$163.7M

Free cash flow (USD)

-$293.7M

Net debt

Net cash position

0.1%

Share dilution

1/5

Graham criteria passed

Defensive-investor screen

Healthcare

Sector

Trajectory

Long-term trends

Revenue by year

2016 → 2025

FY 2016$1.1MFY 2017$27.5MFY 2018$955.0KFY 2019$814.0KFY 2020$853.0KFY 2021$200.6MFY 2022$53.9MFY 2023$91.4MFY 2024$135.2MFY 2025$9.7M
$1.1M$9.7M

Free cash flow by year

2016 → 2025

FY 2016$-133.9MFY 2017$-134.8MFY 2018$-30.0MFY 2019$-53.5MFY 2020$-80.6MFY 2021$92.0MFY 2022$-109.3MFY 2023$-136.7MFY 2024$-150.3MFY 2025$-163.7M
-$133.9M-$163.7M

Gross margin by year

2021 → 2025

FY 2021100.0%FY 2022100.0%FY 2023100.0%FY 2024100.0%FY 202561.8%
100.0%61.8%

Value screen

Graham defensive-investor tests

Computing the scorecard — refreshing any stale inputs…

5

Insider buys · 90 days

0

Insider sells · 90 days

Earnings

Last report: 10-Q filed May 7, 2026

Next expected: not yet scheduled

On the tape

Recent SEC & insider activity

  • Insider buyInsider Buy $158KSCULLY WILLIAM P · 10% Owner · $158KJun 18, 2026Filing
  • Insider buyInsider Buy $1.0MSCULLY WILLIAM P · 10% Owner · $1MJun 12, 2026Filing
  • Insider buyInsider Buy $465KSCULLY WILLIAM P · 10% Owner · $465.3KJun 5, 2026Filing
  • Insider buyInsider Buy $471KSCULLY WILLIAM P · 10% Owner · $471.3KJun 3, 2026Filing
  • Insider buyInsider Buy $981KSCULLY WILLIAM P · 10% Owner · $981.3KMay 26, 2026Filing
  • 8-K eventAnnual Shareholder MeetingMay 15, 2026Filing
  • 8-K eventEarnings ReleaseMay 7, 2026Filing
  • Quarterly report10-Q FiledMay 7, 2026Filing

Questions

Frequently asked questions

What is Prothena Corporation plc's market cap?

Prothena Corporation plc (PRTA) has a market capitalization of $528.8M.

What is PRTA's P/E ratio?

A meaningful P/E ratio is not available for PRTA — the company's latest fiscal-year earnings per share is zero, negative, or not yet cached.

What is PRTA's price-to-book (P/B) ratio?

PRTA trades at 1.89 times book value per share.

Are insiders buying PRTA stock?

Yes — SEC Form 4 filings show 5 open-market insider buys and 0 sells at Prothena Corporation plc in the last 90 days.

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Timeline

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News

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Data: SEC EDGAR filings and cached fundamental data; prices and ratios use the most recent cached quote and statements (may lag by up to a day). Educational and research purposes only. Not investment advice.