Prothena (NASDAQ: PRTA) discloses director Paula Cobb board resignation

Rhea-AI Filing Summary

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.

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

_______________________________________________________

FORM 8-K 

_______________________________________________________

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): December 10, 2025

_______________________________________________________

PROTHENA CORPORATION PUBLIC LIMITED COMPANY

(Exact name of registrant as specified in its charter)

_______________________________________________________

Ireland

001-35676

98-1111119

(State or Other Jurisdiction of Incorporation)

(Commission File Number)

(IRS Employer Identification No.)

77 Sir John Rogerson's Quay, Block C

Grand Canal Docklands

Dublin 2,

D02 VK60,

Ireland

(Address of principal executive offices, including Zip Code)

Registrant’s telephone number, including area code: 011-353-1-236-2500

___________________________________________________

(Former Name or Former Address, if Changed Since Last Report.) 

___________________________________________________

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of Each Class			Trading Symbol			Name of Each Exchange on Which Registered
Ordinary Shares, par value $0.01 per share			PRTA			The Nasdaq Global Select Market

Indicate by check mark whether the registrant is an emerging growth company as defined in as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

                                        Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

    On December 10, 2025, Paula Cobb notified Prothena Corporation plc (the “Company”) of her decision to resign from the Board of Directors of the Company (the “Board”), effective as of December 31, 2025. Ms. Cobb will continue to serve on the Board, the Compensation Committee of the Board, and the Audit Committee of the Board through December 31, 2025. Her decision to resign was not because of a disagreement with the Company on any matter relating to the Company’s operations, policies, or practices.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits.

Exhibit No.						Description
104						Cover Page Interactive Data File (embedded within the Inline XBRL document)

SIGNATURES

    Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Date:

December 12, 2025

PROTHENA CORPORATION PLC

By:

/s/ Tran B. Nguyen

Name:

Tran B. Nguyen

Title:

Chief Strategy Officer and Chief Financial Officer

FAQ

What board change did Prothena (PRTA) report in this filing?

Prothena reported that director Paula Cobb has decided to resign from its Board of Directors, with her departure taking effect at the end of 2025.

When does Paula Cobb’s resignation from Prothena’s board become effective?

Paula Cobb’s resignation from Prothena’s Board of Directors is effective as of December 31, 2025.

Did Paula Cobb resign from Prothena because of a disagreement with the company?

No. Prothena stated that her decision to resign was not because of a disagreement regarding the company’s operations, policies, or practices.

Will Paula Cobb continue serving on any Prothena board committees before her resignation is effective?

Yes. Until December 31, 2025, she will continue serving on the Board, the Compensation Committee, and the Audit Committee.

Where are Prothena’s ordinary shares listed and under what ticker symbol?

Prothena’s ordinary shares are listed on The Nasdaq Global Select Market under the trading symbol PRTA.