Prothena Corporation plc Ordinary Shares (PRTA)

FairStock Score: 46/100 — MIXED

Key Financials

AI Analysis

AI-generated, general educational analysis — not personal investment advice.

I approach Prothena as a clinical-stage speculation, not a Buffett-style compounder. The company has 67 employees and investigational antibodies, including Prasinezumab and Coramitug in Phase 3, but no marketed product is mentioned. Filed results are extremely uneven. In fiscal Q2 2026, the quarter ended 2026-06-30, revenue was $1.0 million and net loss was $18.6 million, or -$0.36 per diluted share. In fiscal Q1 2026, the quarter ended 2026-03-31, revenue was $51.1 million and net income was $32.7 million. For fiscal year 2025, ended 2025-12-31, revenue was $9.7 million and net loss was $244.1 million, or -$4.53 per share, compared with fiscal year 2024, ended 2024-12-31, revenue of $135.2 million and net loss of $122.3 million. Graham would see no stable earning power. At the close on 2026-10-13, price was $8.36, market cap $429.2 million; FairStock calculates P/B 1.51, P/E -10.20, FCF yield -14.1%, Piotroski 2/9, Altman Z-Score 11.16, and FairStock Score 46/100. Low D/E of 0.02 is a positive, but trailing free cash flow is -$60.7 million. I cannot identify a durable moat from these figures; value depends on binary clinical readouts. Without earnings, the price is not cheap on current numbers—it is an option on pipeline success.

In plain English: Prothena is a small drug research company with about 67 employees. It is testing experimental antibody medicines for Parkinson's disease and other illnesses, but it has no approved product mentioned and is losing money. Revenue has been very uneven and recent losses are large. At $8.36 a share, the price is not obviously cheap compared with current sales and profits; much depends on whether its trials succeed.

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Data as of 2026-10-13 close · note generated 2026-10-15 · model deepseek-flash

Sources (SEC EDGAR): fiscal Q2 2026 10-Q (period ended 2026-06-30) · fiscal Q1 2026 10-Q (period ended 2026-03-31) · fiscal Q3 2025 10-Q (period ended 2025-09-30) · fiscal Q2 2025 10-Q (period ended 2025-06-30) · FY2025 10-K (period ended 2025-12-31) · FY2024 10-K (period ended 2024-12-31) · FY2023 10-K (period ended 2023-12-31)

Fundamentals from company filings and market-data providers; prices are end-of-day, not real-time. AI-generated analysis is general and educational — not personal investment advice. Scoring methodology · Score test · Disclaimer