Prothena Corporation plc (PRTA) Stock

Prothena Corporation plc (PRTA) is a Healthcare stock trading at $8.95 (as of 2026-06-18), with a market capitalization of $532.96M and a trailing P/E of -3.6. Figures are sourced from first-party U.S. SEC EDGAR filings and market data.

Prothena Corporation plc is a clinical-stage biopharmaceutical company developing antibody-based therapies for diseases including AL amyloidosis, Parkinson’s disease, and Alzheimer’s disease, as well as transthyretin and related amyloidosis indications. Its pipeline includes Birtamimab and Prasinezumab in later-stage trials and other investigational programs, with collaboration and licensing arrangements supporting development and commercialization.

Valuation — source: SEC EDGAR (first-party)
Price	$8.95
Market Cap	$532.96M
P/E Ratio	-3.6
EV / EBITDA	-1.7
Price / Book	1.70
Price / Sales	9.20
DCF Value (model)	$-46.00
DCF Upside vs Price	-614.3%

Profitability & Growth — source: SEC EDGAR
Revenue (TTM)	$9.68M
Net Margin	-2520.6%
Return on Equity	-48.4%
Current Ratio	10.43
Revenue Growth (YoY)	-92.8%
EPS Growth (YoY)	99.6%

Financial Health — source: SEC EDGAR
Altman Z-Score	-0.66 (distress)

Valuation vs Sector & Industry
Stock P/E	-3.6
Sector P/E (Healthcare)	20.9
Industry P/E (Pharmaceutical Products)	17.0
vs Sector	-117.3%
vs Industry	-121.3%

Smart-Money Activity — SEC Form 4 / 13F / Congressional disclosures
Top Institutional Holder	BlackRock Fund Advisors ($74.53M)
Institutional Holders Tracked	10

Company
Sector	Healthcare
Industry	Pharmaceutical Products
CEO	Gene G. Kinney
Employees	163
Country	IE
IPO Date	2012-12-18

Related Companies (Business model: Biotech (Clinical / Commercial-Stage); 8 closest by market cap; US-domiciled)

Data as of 2026-06-18.

Figures sourced from U.S. Securities and Exchange Commission (SEC EDGAR) filings and market data. Not personalized investment advice.