SCHEDULE: Scully Reports 10.3% Stake in Prothena Corp

William P. Scully has disclosed beneficial ownership of 5,378,846 ordinary shares, representing approximately 10.3% of Prothena Corp Public Ltd Co.

Summary

• William P. Scully has filed a Schedule 13G, indicating beneficial ownership of 5,378,846 ordinary shares of Prothena Corp Public Ltd Co.
• This holding represents approximately 10.3% of the company's outstanding ordinary shares as of April 30, 2026.
• The filing details the breakdown of shares held across various entities and accounts, including Manatee Equity Fund LLC, Scully's IRA, his spouse's IRA, and several grantor retained annuity trusts.
• Scully has sole voting and dispositive power over 793,000 shares and shared power over 4,585,846 shares.
• The filing was made on May 11, 2026, with the event date requiring the filing being May 7, 2026.

Sentiment

Score: 5

Explanation: StockSavvy.ai views this filing as neutral, as it is a routine disclosure of beneficial ownership and does not contain operational or financial performance information.

Positives

• Significant beneficial ownership stake of 10.3% by William P. Scully, indicating substantial investor interest.
• Clear disclosure of shareholdings across multiple entities, providing transparency.
• The filing confirms that the securities were not acquired for the purpose of influencing control of the issuer.

Risks

• Potential for shared voting and dispositive power over a large number of shares (4,585,846) could lead to complex decision-making or influence.
• The retained right to substitute assets in grantor retained annuity trusts could introduce future complexities or potential conflicts.

Future Outlook

The filing does not contain forward-looking statements or guidance. It is a disclosure of beneficial ownership.

Industry Context

StockSavvy.ai notes that Schedule 13G filings are standard disclosures for significant institutional or individual investors acquiring more than 5% of a public company's stock. This filing indicates a substantial investment in Prothena Corp by William P. Scully, positioning him as a key stakeholder.

Stakeholder Impact

• Shareholders: The disclosure of a significant stake by William P. Scully may influence market perception and potentially impact share trading dynamics.
• Management: The substantial ownership by Scully may lead to increased engagement or scrutiny from this significant stakeholder.

Key Dates

Keywords

Schedule 13G, Prothena Corp, William P. Scully, Beneficial Ownership, Ordinary Shares, SEC Filing, Investment, Shareholder