Prothena Corporation announced a new share repurchase program authorizing up to $100 million in buybacks of its ordinary shares, a move that coincided with a 4.7% increase in the company's stock during after-hours trading on Friday.
The company stated that repurchases may occur intermittently through open market transactions. Such purchases could be structured in conformity with Rule 10b-18 of the Securities Exchange Act of 1934. Prothena also indicated it may adopt Rule 10b5-1 plans to manage and facilitate repurchases.
In its most recent financial disclosure, Prothena reported cash, cash equivalents and restricted cash totaling $308.4 million and noted it had no debt as of December 31, 2025. The company projects it will finish the year with approximately $255 million in cash, cash equivalents and restricted cash, an estimate that excludes any expenditures related to the newly authorized share repurchase program.
Prothena emphasized that the timing, quantity of shares repurchased and the prices paid will be responsive to prevailing business and market conditions, observable share prices and other factors the company deems relevant. The repurchase authority will expire on December 31, 2026. Management said the program may be suspended or discontinued at any time and does not create an obligation to purchase any specific number of shares.
The company noted that its current financial guidance does not factor in the possible receipt of up to $105 million in aggregate clinical milestone payments from strategic partners in 2026. Those potential payments are linked to the advancement of coramitug for ATTR amyloidosis with cardiomyopathy by Novo Nordisk and to PRX019 for neurodegenerative diseases by Bristol Myers Squibb.
Context and considerations - The buyback authorization provides Prothena with the flexibility to return capital to shareholders while retaining discretion over execution. The stated cash position and absence of debt give the company room to pursue repurchases without the immediate need to alter its stated guidance. However, Prothena's guidance explicitly excludes possible partner milestone receipts, which could materially affect available resources if realized.
Investors should note the company 27s right to pause or stop the repurchase program and that actual repurchases will depend on market conditions and other business considerations.