Welcome to our dedicated page for Prothena SEC filings (Ticker: PRTA), a comprehensive resource for investors and traders seeking official regulatory documents including 10-K annual reports, 10-Q quarterly earnings, 8-K material events, and insider trading forms.
The Prothena Corporation plc (NASDAQ: PRTA) SEC filings page on Stock Titan brings together the company’s regulatory disclosures from the U.S. Securities and Exchange Commission, alongside AI-powered summaries designed to make these documents easier to understand. Prothena is an Irish public limited company whose ordinary shares trade on The Nasdaq Global Select Market, and it files reports such as Forms 8-K and proxy statements in connection with material events and shareholder meetings.
Recent 8-K filings referenced by the company include disclosures about quarterly financial results, workforce reductions following the discontinuation of the birtamimab program, collaboration developments such as Novo Nordisk advancing coramitug (formerly PRX004) for ATTR amyloidosis with cardiomyopathy, and updates on the PRX012 Phase 1 ASCENT clinical program. Other 8-Ks describe governance and compensation matters, including employment agreements for senior officers and the planned resignation of a Board member, as well as the outcome of an Extraordinary General Meeting where shareholders approved a reduction of capital to create distributable reserves.
Prothena’s definitive proxy statement for the Extraordinary General Meeting explains the rationale for the capital reduction and outlines voting procedures for shareholders of the Irish public limited company. These filings, together with the company’s periodic reports referenced in its press releases, form the official record of Prothena’s financial condition, capital structure decisions, and key operational events.
On Stock Titan, users can access Prothena’s SEC filings as they are made available through EDGAR and use AI-generated highlights to quickly identify the main points in lengthy documents. For PRTA, this can include understanding how collaboration revenue from partners like Bristol Myers Squibb is reported, how restructuring charges are described, and how shareholder approvals are documented in connection with potential share redemption programs and other capital management actions.
Nguyen Tran reported acquisition or exercise transactions in this Form 4 filing.
PROTHENA CORP PUBLIC LTD CO granted Nguyen Tran, its Chief Strategy Officer and CFO, a stock option covering 230,000 shares. The option vests as to 25% of the shares on March 3, 2027, with the remaining 75% vesting in equal monthly installments over the following three years, subject to continued employment.
Malecek Michael J reported acquisition or exercise transactions in this Form 4 filing.
Prothena Corp Public Ltd Co granted Chief Legal Officer Michael J. Malecek a stock option covering 190,000 shares of the company’s stock. According to the award terms, 25% of the option will vest and become exercisable on March 3, 2027. The remaining shares will vest in equal monthly installments of 1/48th of the total option on each monthly anniversary thereafter, subject to his continued employment with the company on each vesting date.
Kinney Gene G. reported acquisition or exercise transactions in this Form 4 filing.
PROTHENA CORP PUBLIC LTD CO reported that President and CEO Gene G. Kinney received a grant of stock options covering 520,000 shares on March 3, 2026. These options vest as to 25% of the total shares on March 3, 2027, then in equal monthly installments of 1/48th of the total shares on each monthly anniversary thereafter, subject to his continued employment with the company.
Prothena Corporation plc announced that its board has authorized a share repurchase plan allowing the company to buy back up to $100.0 million of its outstanding ordinary shares. The plan runs through December 31, 2026, is fully discretionary, and can be suspended or ended at any time.
Prothena reported $308.4 million in cash, cash equivalents and restricted cash and no debt as of December 31, 2025, and expects to end 2026 with about $255 million in cash excluding any repurchases. The company also highlights potential to earn up to $105 million in 2026 clinical milestone payments from strategic partners Novo Nordisk and Bristol Myers Squibb.
Prothena Corporation plc amends its S-3 shelf to register up to $200,000,000 of ordinary shares for issuance from time to time after the registration statement is effective. This post-effective amendment also states the company is no longer a well-known seasoned issuer.
Each future issuance will be described in a prospectus supplement that sets amounts, prices and terms. The filing discloses issued ordinary shares of 53,832,982 as of December 31, 2025 as a context figure.
Prothena Corporation plc filed its annual report describing a late-stage biotechnology company focused on diseases caused by protein misfolding, particularly neurodegenerative and rare amyloid disorders. Its pipeline spans wholly owned and partnered antibody, small‑molecule and vaccine programs.
Key partnered assets include prasinezumab with Roche for Parkinson’s disease, coramitug with Novo Nordisk for ATTR cardiomyopathy, and BMS-986446 and PRX019 with Bristol Myers Squibb for Alzheimer’s and other neurodegenerative diseases. Early programs feature the CYTOPE® intracellular targeting platform, Alzheimer’s candidates PRX012 and PRX012‑TfR, and dual Aβ‑tau vaccine PRX123.
The company discontinued development of birtamimab after the Phase 3 AFFIRM‑AL trial failed to meet its endpoints and implemented an approximate 63% workforce reduction in 2025 to lower operating costs while continuing to support key collaborations and selected wholly owned projects.
Prothena Corporation plc amends its shelf registration to permit the offer and issuance of up to $200,000,000 of ordinary shares from time to time. This Post-Effective Amendment notes the company will no longer qualify as a well-known seasoned issuer after filing its Annual Report for the year ended December 31, 2025.
The prospectus describes the general terms for future takedowns under the shelf, the requirement that each offering be accompanied by a prospectus supplement with specific amounts, prices and terms, and that offerings may be conducted through underwriters, dealers, agents or directly to purchasers.
Prothena Corporation plc reported significantly weaker 2025 financial results while highlighting progress across its partnered neurology pipeline. For 2025, the company posted a net loss of $244.1 million, nearly double the prior year’s $122.3 million, as revenue fell to $9.7 million from $135.2 million driven by lower collaboration payments.
Research and development expenses declined to $134.9 million and general and administrative expenses to $59.4 million, reflecting lower clinical, personnel, manufacturing, and consulting costs, though results included $30.1 million of restructuring charges and a $43.2 million non-cash tax expense. Prothena ended 2025 with $308.4 million in cash, cash equivalents and restricted cash and no debt, and had about 53.8 million ordinary shares outstanding as of February 12, 2026.
For 2026, Prothena expects net cash used in operating and investing activities of $50–$55 million and to finish the year with roughly $255 million in cash at the midpoint, excluding up to $105 million of potential clinical milestone receipts from partners. The company also secured shareholder and court approval to create distributable reserves, allowing its board to consider a share redemption program in 2026 at its discretion, and noted multiple late-stage trials with Roche, Novo Nordisk, and Bristol Myers Squibb targeting Parkinson’s, ATTR amyloidosis, and Alzheimer’s disease.
Rubric Capital Management LP and David Rosen disclosed beneficial ownership of Prothena Corporation plc’s ordinary shares. They report holding 3,677,331 ordinary shares, representing 6.83% of the outstanding class.
The percentage is calculated based on 53,829,982 ordinary shares outstanding as of October 31, 2025, as reported by Prothena. Rubric Capital Master Fund LP has the right to receive dividends or sale proceeds on more than 5% of the shares. The investors state that the shares are held in the ordinary course of business and not for the purpose of changing or influencing control of Prothena.
Prothena Corporation plc disclosed that director Paula Cobb has decided to resign from its Board of Directors, effective December 31, 2025. Until that date, she will continue serving on the Board as well as on the Compensation Committee and the Audit Committee.
The company stated that Ms. Cobb’s decision to step down was not because of any disagreement with Prothena on matters related to its operations, policies, or practices, suggesting this is a routine governance change rather than a dispute-driven departure.