Every 8-K that Prothena Corporation plc (PRTA) has filed with the SEC in the last 24 months is listed below, newest first, and each one links through to the document itself with the summary and the scores our analysis gives it.
A 8-K covers material events a company has to report between its quarterly reports, so if you follow PRTA and want that one kind of document rather than the whole filing history, this is the page to keep. The company's other filings, of every form, are on the full PRTA filings page.
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.
Prothena Corporation plc reported the results of its annual general meeting of shareholders. Shareholders re-elected Shane M. Cooke and Dennis J. Selkoe to the Board of Directors to serve until no later than the annual general meeting in 2029.
Shareholders also ratified, in a non-binding vote, the appointment of KPMG LLP as independent registered public accounting firm for the fiscal year ending December 31, 2026, and gave the Board, through its Audit Committee, binding authority to approve the auditor’s remuneration. In a separate non-binding advisory vote, shareholders approved the compensation of the Company’s named executive officers.
Prothena Corporation plc reported strong first quarter 2026 results, with total revenue of $51.1 million and net income of $32.7 million, compared with a net loss of $60.2 million a year earlier. Results were driven mainly by a $50 million milestone payment from Novo Nordisk and lower research and development and general and administrative expenses, plus a $4.2 million restructuring credit.
Quarter-end cash, cash equivalents and restricted cash were $330.3 million and the company had no debt. Prothena cut its projected 2026 net cash used in operating and investing activities to $18–$23 million and now expects to end 2026 with about $273 million in cash (midpoint). It also authorized a 2026 share repurchase program for up to $100 million, repurchasing 788,990 shares for $7.3 million through March 31, 2026.
Operationally, Novo Nordisk obtained U.S. FDA Fast Track designation for coramitug and paid the $50 million milestone, Roche presented multiple positive prasinezumab data updates, Prothena completed a Phase 1 study for PRX019 with potential for a $55 million milestone from Bristol Myers Squibb, and preclinical CYTOPE and PRX012-TfR programs continued to advance.
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 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.
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.
Prothena Corporation plc reported the results of an extraordinary general meeting of shareholders held on November 19, 2025. Shareholders considered a single proposal to approve a reduction of the Company’s capital to create distributable reserves.
The proposal was approved with 37,779,052 votes in favor, 46,738 against, and 45,906 abstentions. Creating distributable reserves is an Irish corporate law mechanism that can give a company more flexibility to make future distributions, such as dividends or other returns of value, if its board later chooses to do so and other legal requirements are met. This update reflects a change in Prothena’s capital structure authorization rather than an immediate financial transaction.
Prothena Corporation plc furnished a press release announcing its financial results for the third quarter ended September 30, 2025. The press release is attached as Exhibit 99.1 to a current report on Form 8-K dated November 6, 2025. The company states that the information provided under Item 2.02 and Exhibit 99.1 is furnished and not deemed “filed” under Section 18 of the Exchange Act.
Prothena Corporation plc filed a report stating that it issued a press release on August 27, 2025. The release provides an update on its PRX012 investigational drug and shares results from the Phase 1 ASCENT clinical program. The press release is included as Exhibit 99.1 and is incorporated by reference, meaning the detailed clinical information is contained in that exhibit rather than in this summary document.