Prothena Corporation (PRTA) Stock Fundamentals, Analysis & Risk Signals

Health score, price, valuation, risk signals, and key metrics at a glance.

Prothena Corporation

NasdaqGS•Healthcare•Biotechnology

$9.54-0.28(-0.03%)Pre-market

Market Cap

$465.65M

P/S

8.5x

P/B

1.6x

Prothena Corporation plc, a late-stage clinical biotechnology company, focuses on discovery and development of novel therapies to treat diseases caused by protein dysregulation. Its product pipeline includes Prasinezumab, an investigational humanized monoclonal antibody which is in Phase 3 clinical trial for the treatment of parkinson's disease and other synucleinopathies. The company also develops Coramitug, an investigational antibody, which is in Phase 3 clinical trial for the treatment of transthyretin amyloidosis; BMS-986446, an anti-tau antibody which is in Phase 2 clinical trial to treat Alzheimer's disease; PRX019, an investigational antibody which is in Phase 1 clinical trial for the treatment of neurodegenerative diseases; and PRX123, a Dual Aß-Tau Vaccine, which is in preclinical trial for treating Alzheimer's disease. In addition, it develops discovery- and late-preclinical-stage programs include TDP-43 CYTOPE for the treatment of amyotrophic lateral sclerosis; PRX012, a next-generation anti-Aß antibody which is in phase 1 clinical trial to treat Alzheimer's disease; and PRX012-TfR, a preclinical program for the treatment of Alzheimer's disease. It has a license, development, and commercialization agreement with F. Hoffmann-La Roche Ltd. and Hoffmann-La Roche Inc. to develop and commercialize antibodies that target a-synuclein, including prasinezumab; and master collaboration agreement with Bristol Myers Squibb to develop and commercialize antibodies targeting tau, TDP-43. Prothena Corporation plc was incorporated in 2012 and is based in Dublin, Ireland.

How this company scores

AverageMetricSide Score: 58/100

Strongest: Growth (20/25); weakest: Cash & Earnings Quality (9/25).

Profitability14/25

Growth20/25

Balance Sheet & Red Flags15/25

Cash & Earnings Quality9/25

Strengths

Growing revenueLong cash runwayInterest easily coveredProfit converts from growth

Valuation vs. 5-year range

Today's multiple positioned against its own trailing range — a visual premium/discount check.

P/E · 14.4x5y range 13.6x – 14.4x

P/S · 8.5x5y range 4.7x – 188.9x

Currently near its 20-quarter median.

P/B · 1.6x5y range 1.0x – 2.4x

Watch items

Data-driven signals worth keeping an eye on across the last 8 quarters

High Risk

Margin Pressure

Red Flag

The company posted negative operating margins in recent quarters — core operations are unprofitable.

Earnings Quality

Red Flag

Free cash flow has been negative in 7 of the last 8 quarters — earnings are not translating to cash.

Price & Volume

Market Cap $465.65M

Metrics at a Glance

as of June 2026

Revenue & Profit

Revenue, EBITDA, operating income, net income, EPS, and shares

TTM Revenue: $54.53M
Q. Revenue: $1.01M
TTM EBITDA: $-54.68M
TTM Op. Income: $-55.51M
Q. Op. Income: $-21.10M
TTM Net Income: $-43.99M
Q. Net Income: $-18.58M
EPS: $-0.36
Shares Out.: $52.15M

$54.53M in TTM revenue grew 427.3% YoY, reaching $1.01M last quarter. TTM EBITDA of $-54.68M and TTM operating income of $-55.51M show growth is flowing through to the bottom line. However, net income is negative at $43.99M — growth is not yet reaching the bottom line. Over the past year, TTM revenue is up 427% — a weakening trend.

Margins

Gross, EBITDA, operating, and net margin trends

EBITDA Margin: -2069.7%
Op. Margin: -2089.2%
Net Margin: -1839.9%

Op. margin of -2089.2% is down 174.8% YoY — costs are rising relative to revenue. Net margin at -1839.9% Over the past year, operating margin is down 9% — a weakening trend.

Price Ratios

P/E, P/S, P/B, EV/EBITDA, FCF yield, and earnings yield

P/E Ratio: N/A
P/S Ratio: 8.5x
P/B Ratio: 1.6x

P/S of 8.5x and P/B of 1.6x.

Assets & Liabilities

Total assets, cash, debt, book value, and leverage

Total Assets: $302.58M
Cash: $288.19M
Long-Term Debt: N/A
Book Value: $286.89M
D/E Ratio: N/A
Debt/EBITDA: N/A

Cash Flow

Operating cash flow, free cash flow, FCF margin, and earnings quality

Op. Cash Flow: $-25.05M
TTM Free Cash Flow: $-60.71M
FCF Margin: -111.3%
FCF / Net Income: 1.4

TTM FCF of $-60.71M on $-25.05M in operating cash flow. The FCF / Net Income ratio of 1.4x means free cash flow covers net income — earnings are backed by cash. Across the last 8 quarters, free cash flow has risen for 4 consecutive quarters — an improving trend.