---
schema_version: "secwatch.filing_event.v1"
accession: "0001559053-26-000003"
form_type: "8-K"
ticker: "PRTA"
cik: "0001559053"
company_name: "PROTHENA CORP PUBLIC LTD CO"
filed_at: "2026-02-19T23:59:59+00:00"
generated_at: "2026-05-16T01:43:56.556942+00:00"
event_type: "earnings"
sentiment: "negative"
materiality_score: 0.75
calibrated_materiality_score: 0.75
confidence: "high"
source: SEC EDGAR
---

# Prothena posts Q4 2025 net loss $21.6M; full-year loss $244.1M; 2026 cash burn guide $50-55M

## Summary
- Net loss $21.6M ($0.40 EPS) in Q4 vs $58.0M loss ($1.08 EPS) in Q4 2024; full-year loss $244.1M ($4.53 EPS).
- Total revenue $21K in Q4 vs $2.1M a year ago; full-year revenue $9.7M vs $135.2M in 2024.
- Cash & restricted cash $308.4M at Dec 31, 2025; no debt; shares outstanding ~53.8M.
- 2026 guidance: net cash used in ops $50-55M; year-end cash ~$255M; excludes up to $105M milestones.
- Partners Roche, Novo Nordisk, BMS initiated Phase 3 trials for prasinezumab, coramitug, and BMS-986446.

## SEC filing metadata
- accession: 0001559053-26-000003
- form_type: 8-K
- ticker: PRTA
- cik: 0001559053
- company_name: PROTHENA CORP PUBLIC LTD CO
- filed_at: 2026-02-19T23:59:59+00:00
- event_type: earnings
- sentiment: negative
- materiality_score: 0.75
- calibrated_materiality_score: 0.75
- confidence: high
- sec_items: 2.02, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1559053/000155905326000003/0001559053-26-000003-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1559053/000155905326000003/prta-20260219.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001559053-26-000003
- JSON: https://secwatch.observer/filing/0001559053-26-000003.json
- Plain text: https://secwatch.observer/filing/0001559053-26-000003.txt

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.