Prothena Corp Public Ltd Co (PRTA) · Nov 5, 2026 · Earnings

Prothena earnings miss as milestone revenue vanishes; cash guidance holds

Miss — EPS $(0.32) vs ~$(0.23) consensus; revenue $0.62M vs ~$9.58M

Prothena’s Q3 earnings missed published expectations on sharply lower revenue, while cash-burn guidance held and partnered pipeline milestones remained intact.

Prothena is a late-stage biotech whose value rests mainly on partnered Phase 3 assets—prasinezumab with Roche and coramitug with Novo—while it funds a smaller wholly owned preclinical pipeline. The quarter shows the financial profile of that model: little recurring revenue, heavy dependence on partner milestones, and a long wait for clinical readouts. Published estimates for Q3 were roughly a $0.23 per-share loss and $9.58 million of revenue.

The quarter missed the available benchmark by a wide margin. Revenue was just $0.6 million versus $2.4 million a year earlier and approximately $9.6 million of published consensus, while the $0.32 per-share loss was worse than the roughly $0.23 consensus loss. The revenue shortfall is especially important because the prior nine-month figure was inflated by a $50.0 million Novo milestone, not by a recurring commercial stream. (Financial Highlights)

Q3 2026Q3 2025Consensus
Total revenue (Financial Highlights)$0.6M (-74.3%)$2.4M~$9.58M
Net loss per share (Financial Highlights)$(0.32)$(0.68)~$(0.23)
R&D expense (Financial Highlights)$8.4M (-70.9%)$28.9M
Cash and restricted cash (Financial Highlights)$272.2M

Lower spending cushions the miss but does not replace the missing milestone revenue. R&D fell to $8.4 million from $28.9 million, and total operating expenses dropped to $19.4 million from $42.7 million, reflecting lower trial, personnel, and consulting costs. That improved the loss versus last year, but it also reflects a company operating with less internally funded clinical activity; the partnered Phase 3 programs remain the core source of future value. (Research and development expenses; Financial Highlights)

The balance-sheet message is steadier than the income statement. Prothena reaffirmed full-year 2026 net cash used in operating and investing activities of $18 million to $23 million and an approximately $259 million year-end cash, cash-equivalents, and restricted-cash balance. It ended the quarter with $272.2 million, while repurchasing $26.6 million of shares through nine months. (Financial Guidance; Share Repurchase Program)

The pipeline itself is advancing, but the next meaningful proof points remain distant. Roche and Novo are running Phase 3 trials of prasinezumab and coramitug with primary completion expected in 2029, while BMS’s moponetug program has a data readout expected in the first half of 2027. The new coramitug biomarker analysis is supportive, but it is post hoc Phase 2 evidence rather than a clinical outcome that changes the development bar. (Business Highlights)

Bottom line: This was a clear earnings miss driven by the absence of milestone revenue, not a deterioration in the stated cash plan. The pipeline story is still intact, but the quarter adds little near-term financial support and reinforces how dependent Prothena remains on partner-driven milestones and distant clinical catalysts.

What to watch next

Moponetug Phase 2 data readout expected in first half 2027

Original filing on SEC EDGAR

More Prothena Corp Public Ltd Co news

Prothena earnings miss as milestone revenue vanishes; cash guidance holds | PRTA Stock News
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