---
schema_version: "secwatch.filing_event.v1"
accession: "0001559053-26-000021"
form_type: "8-K"
ticker: "PRTA"
cik: "0001559053"
company_name: "PROTHENA CORP PUBLIC LTD CO"
filed_at: "2026-08-06T20:16:21+00:00"
generated_at: "2026-08-06T20:20:05.507804+00:00"
event_type: "earnings"
sentiment: "neutral"
materiality_score: 0.65
calibrated_materiality_score: 0.65
confidence: "high"
source: SEC EDGAR
---

# Prothena reports Q2 net loss of $18.6M, revenue $1.0M; updates cash guidance to ~$259M

## Summary
- Net loss of $18.6M in Q2 2026 vs $125.8M loss in Q2 2025; basic EPS loss $0.36 vs $2.34.
- Total revenue $1.0M in Q2, $52.1M in H1 2026 (includes $50M Novo Nordisk milestone).
- Cash and restricted cash $289.1M at June 30, 2026; no debt.
- Updated FY 2026 year-end cash guidance to ~$259M (midpoint), down $14M from prior due to share repurchases.
- Repurchased 2,243,888 shares in H1 2026 for $22.3M under $100M program; $55M milestone from BMS possible by YE.

## SEC filing metadata
- accession: 0001559053-26-000021
- form_type: 8-K
- ticker: PRTA
- cik: 0001559053
- company_name: PROTHENA CORP PUBLIC LTD CO
- filed_at: 2026-08-06T20:16:21+00:00
- event_type: earnings
- sentiment: neutral
- materiality_score: 0.65
- calibrated_materiality_score: 0.65
- confidence: high
- sec_items: 2.02, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1559053/000155905326000021/0001559053-26-000021-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1559053/000155905326000021/prta-20260806.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001559053-26-000021
- JSON: https://secwatch.observer/filing/0001559053-26-000021.json
- Plain text: https://secwatch.observer/filing/0001559053-26-000021.txt

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