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Prothena Corporation plc, a late-stage biotech focused on protein dysregulation, reported mixed results for the three and six months ended June 30, 2026. For the quarter, total revenue was $1,010 thousand and the company recorded a net loss of $18,583 thousand, or $0.36 per share, narrower than a year earlier. For the first half, total revenue rose to $52,094 thousand, including a $50,050 thousand development milestone from Novo Nordisk related to coramitug, driving net income of $14,138 thousand compared with a substantial loss in 2025.
Operating expenses fell sharply as research and development declined to $21,425 thousand for the six-month period and restructuring charges reversed to a net credit, reflecting wind-down of the birtamimab program and progress on a 2025 restructuring plan. Net cash provided by operating activities was $3,828 thousand, and cash, cash equivalents and restricted cash totaled $289,053 thousand at June 30, 2026; management believes this is sufficient to meet obligations for at least the next twelve months.
The company repurchased 2,243,888 ordinary shares for approximately $22.3 million under a $100.0 million authorization. Clinically, key partnered programs advanced, including Roche’s Phase 3 PARAISO trial of prasinezumab in early Parkinson’s disease and Novo Nordisk’s Phase 3 CLEOPATTRA trial of coramitug in ATTR cardiomyopathy, supported by earlier positive Phase 2 data and recent FDA Fast Track designations.
Prothena Corporation plc reported second quarter 2026 results with a net loss of $18.6 million, and net income of $14.1 million for the first six months of 2026, compared with a $185.9 million loss a year earlier. Total revenue was $1.0 million for the quarter and $52.1 million year-to-date, mainly from a $50.0 million milestone payment from Novo Nordisk and collaboration revenue from Bristol Myers Squibb.
Research and development and general and administrative expenses decreased substantially versus 2025, reducing operating losses. Cash, cash equivalents and restricted cash were $289.1 million as of June 30, 2026, with no debt. Prothena repurchased 2,243,888 ordinary shares for $22.3 million in the first half of 2026 under its up to $100.0 million share repurchase program. For 2026, the company expects net cash used in operating and investing activities of $18–$23 million and year-end cash, cash equivalents and restricted cash of about $259 million, excluding any potential $55 million milestone from Bristol Myers Squibb.
FMR LLC reported beneficial ownership of common stock of Prothena Corporation plc. FMR LLC held 7,199,218 shares, representing 13.8% of the outstanding common stock as of June 30, 2026, with sole power to dispose of all such shares and no shared voting or dispositive power.
Abigail P. Johnson is reported with sole dispositive power over the same 7,199,218 shares, but no sole or shared voting power. The filing notes that one or more other persons have rights to receive dividends or sale proceeds, including Fidelity Growth Company Commingled Pool, whose interest amounted to 3,335,877 shares, or 6.4% of Prothena’s common stock as of June 30, 2026.
Prothena Corp Public Ltd Co Chief Scientific Officer Wagner M. Zago exercised 51,000 restricted stock units into an equal number of ordinary shares on July 28, 2026. These units were part of an 85,000 RSU grant made on July 28, 2025. On the same date, he reported a transaction coded as a disposition to the issuer of 51,000 ordinary shares at $8.56 per share. Footnotes state that 34,000 RSUs from the 2025 grant remain subject to vesting.
On July 28, 2026, Prothena Corp Public Ltd Co Chief Accounting Officer Karin L Walker exercised 15,000 restricted stock units into 15,000 ordinary shares, then disposed of 15,000 shares back to the issuer at $8.56 per share. These 15,000 RSUs, part of a 25,000-unit grant made on July 28, 2025, became fully vested on the one-year anniversary; the remaining 10,000 RSUs from that grant continue to be subject to vesting.
PROTHENA CORP PUBLIC LTD CO Chief Development Officer Chad J. Swanson exercised 51,000 restricted stock units into the same number of ordinary shares on July 28, 2026. On the same date he returned 40,800 shares to the issuer and had 3,467 shares withheld at $8.56 per share to pay the exercise price or tax liabilities. These RSUs were part of an 85,000‑unit grant made July 28, 2025, of which 34,000 RSUs remain subject to vesting.
PROTHENA CORP PUBLIC LTD CO reported that Chief Operating Officer Brandon S. Smith exercised 78,000 restricted stock units into the same number of ordinary shares on July 28, 2026, then disposed of 78,000 shares back to the issuer at $8.56 per share. These RSUs were part of a 130,000-unit grant from July 28, 2025, of which 52,000 RSUs remain subject to vesting.
PROTHENA CORP PUBLIC LTD CO officer Nguyen Tran, Chief Strategy Officer and CFO, exercised 57,000 restricted stock units into 57,000 ordinary shares on July 28, 2026, and on the same date disposed 57,000 ordinary shares to the issuer at $8.56 per share. These RSUs were part of a 95,000-unit award granted July 28, 2025; 38,000 RSUs from that grant remain subject to vesting.
PROTHENA CORP PUBLIC LTD CO President and CEO Gene G. Kinney exercised 84,000 restricted stock units into the same number of ordinary shares on July 28, 2026. These units were part of a 140,000 RSU grant awarded on July 28, 2025. On the same date, he disposed 84,000 ordinary shares back to the issuer at $8.56 per share. According to the award terms, the remaining 56,000 RSUs from that grant are still subject to future vesting.
Prothena Corp Public Ltd Co Chief Strategy Officer Anne Evans Kingston reported selling 7,662 ordinary shares on July 29, 2026 at a weighted average price of $8.4729, in multiple trades between $8.40 and $8.64, under a Rule 10b5-1 trading plan adopted on March 30, 2026. On July 28, 2026, 3,498 shares were disposed of at $8.56 per share to satisfy tax obligations by delivering or withholding securities.