Company: PRTA
Filing Date: 2025-06-18
Form Type: 8-K
Source: 0001193125-25-142725
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Company: PROTHENA CORP PUBLIC LTD CO
Filing Date: 2025-06-18
Form: 8-K
Item: Item 2.05
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Item 2.05      Costs Associated with Exit or Disposal Activities.  

On June 18, 2025, Prothena Corporation plc (the “ Company”) announced an approximate 63% reduction in its workforce to substantially reduce its operating costs to those necessary to support its remaining wholly-owned programs, its obligations to partnered programs, and its anticipated business development activities. This workforce reduction follows the Company’s May 23, 2025 announcement of its decision to discontinue further development of birtamimab. The Company expects the workforce reduction to be substantially complete by the end of the fourth quarter of 2025.

Affected U. S. employees are eligible to receive severance payments and benefits under the Prothena Biosciences Inc Amended and Restated Severance Plan. Affected non-U. S. employees are eligible to receive statutory and/or contractual payments under the terms of their employment agreements and/or local legal requirements. In the case of certain senior executives, vesting of portions of their stock options will be accelerated and the post-employment exercise periods will be extended, pursuant to the terms of the option award agreements under which those stock options were granted.

The Company expects to recognize approximately $16 to $20 million in total for severance and related benefits for employees laid off under the reduction in workforce and non-cashshare-based compensation expense related to the acceleration of stock options. These charges are primarily one-timeseverance payments and are primarily cash charges. The Company may also incur other charges or cash expenditures not currently contemplated due to events that may occur as a result of, or associated with, the reduction in workforce.

Additional details will be provided in the Company’s Quarterly Reports on Form 10-Qfor the periods ending June 30, 2025, and September 30, 2025, and the Company’s Annual Report onForm 10-Kfor the period ending December 31, 2025.