Prothena Corporation plc Ordinary Shares

Day range

$7.93 – $8.27

Open

$8.18

Prev close

$8.25

Volume

386.14K

Market cap

$423.53M

Shares out

52.35M

P/E

—

P/S

7.77

P/B

1.48

P/FCF

—

ROE

-15.3%

ROA

-14.5%

Debt/Equity

0.00

Div yield

0.00%

As of Oct 22, 2026

• Executive leadershipOct 2, 2026

  On October 2, 2026, Chad J. Swanson, Ph.D., Chief Development Officer of Prothena Corporation plc (the "Company") notified the Company that he is resigning from the Company effective October 9, 2026. Dr. Swanson is resigning to accept a position with one of the Company's strategic partners, and, as part of his new role, will assume a leadership role over a program partnered with the Company.

• Shareholder meetingsMay 15, 2026

  On May 14, 2026, Prothena Corporation plc (the "Company") held its annual general meeting of shareholders, at which the Company's shareholders voted on the following proposals... Proposal No. 1: Election of Directors. The shareholders re-elected the following individuals to the Company's Board of Directors to hold office until no later than the annual general meeting of shareholders in 2029.

• Shareholder returnsFeb 27, 2026

  On February 27, 2026, the Company announced a share repurchase plan under which the Company may repurchase up to $100.0 million of the Company's outstanding ordinary shares, par value $0.01 per share. The share repurchase plan will expire on December 31, 2026, may be suspended or discontinued at any time, and does not obligate the company to acquire any amount of ordinary shares.

• Board of directorsDec 12, 2025

  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.

• Shareholder meetingsNov 19, 2025

  On November 19, 2025, Prothena Corporation plc (the "Company") held an extraordinary general meeting of shareholders, at which the Company's shareholders voted on the following proposal... The shareholders approved a reduction of the Company's capital to create distributable reserves. | For | Against | Abstain | | 37,779,052 | 46,738 | 45,906 |

Days to cover

13.8

Short interest

8.01M

Avg volume

580.89K

As of Sep 30, 2026 · reported to FINRA twice monthly.

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