STOCK TITAN

Prothena (PRTA) 10% owner William Scully buys 20,000 shares

Filing Impact
(Moderate)
Filing Sentiment
(Positive)
Form Type
4

Rhea-AI Filing Summary

PROTHENA CORP PUBLIC LTD CO large shareholder William P. Scully reported an open-market purchase of 20,000 ordinary shares of PRTA. The transaction occurred on June 16, 2026 at a weighted average price of $7.8995 per share, with individual trades between $7.8600 and $7.9312.

After this purchase, Scully directly holds 756,000 ordinary shares. The filing also shows indirect holdings of 52,000 shares held by his spouse and 80,000 shares held by Manatee Equity Fund LLC, for which he disclaims beneficial ownership except to the extent of his pecuniary interest.

Positive

  • None.

Negative

  • None.
Insider SCULLY WILLIAM P
Role null
Bought 20,000 shs ($158K)
Type Security Shares Price Value
Purchase Ordinary Shares, par value $0.01 per share 20,000 $7.8995 $158K
holding Ordinary Shares, par value $0.01 per share -- -- --
holding Ordinary Shares, par value $0.01 per share -- -- --
Holdings After Transaction: Ordinary Shares, par value $0.01 per share — 756,000 shares (Direct, null); Ordinary Shares, par value $0.01 per share — 80,000 shares (Indirect, By Manatee Equity Fund LLC)
Footnotes (1)
  1. The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $7.8600 to $7.9312, inclusive. The reporting person undertakes to provide to Prothena Corp Public Ltd Co, any security holder of Prothena Corp Public Ltd Co, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnote (1) to this Form 4. The reporting person disclaims beneficial ownership of these securities except to the extent of his pecuniary interest therein.
Open-market purchase 20,000 shares Ordinary shares bought on June 16, 2026
Purchase price $7.8995 per share Weighted average price for 20,000 shares
Price range $7.8600–$7.9312 per share Range of individual trade prices
Direct holdings after trade 756,000 shares Ordinary shares held directly by Scully
Indirect holdings by spouse 52,000 shares Ordinary shares held indirectly by spouse
Indirect holdings via LLC 80,000 shares Ordinary shares held by Manatee Equity Fund LLC
open-market purchase financial
"transaction_action: "open-market purchase""
An open-market purchase is when an investor or a company buys shares on a public stock exchange at the going market price, rather than through a private deal. It matters to investors because these purchases change how many shares are available, can push the stock price up or signal confidence from large buyers, and often affect per-share metrics like earnings—think of it like someone buying lots of apples off a grocery shelf, reducing supply and potentially raising the price.
weighted average price financial
"The price reported in Column 4 is a weighted average price."
Weighted average price is the average price of a security where each trade or component is counted according to its size, so bigger trades pull the average more than smaller ones. Think of it like calculating the average cost of a grocery haul where items you bought more of have greater influence on the final per-item cost. Investors use it to understand the true average price paid or received, judge execution quality, and compare trading performance against market movement.
beneficial ownership financial
"The reporting person disclaims beneficial ownership of these securities"
Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.
pecuniary interest financial
"except to the extent of his pecuniary interest therein."
indirect ownership financial
"ownership_type: "indirect" and nature_of_ownership: "By Spouse""
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SEC Form 4
FORM 4UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940
OMB APPROVAL
OMB Number:3235-0287
Estimated average burden
hours per response:0.5
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.
1. Name and Address of Reporting Person*
SCULLY WILLIAM P

(Last)(First)(Middle)
771 MANATEE COVE

(Street)
VERO BEACH FLORIDA 32963

(City)(State)(Zip)

UNITED STATES

(Country)
2. Issuer Name and Ticker or Trading Symbol
PROTHENA CORP PUBLIC LTD CO [ PRTA ]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
DirectorX10% Owner
Officer (give title below)Other (specify below)
2a. Foreign Trading Symbol
3. Date of Earliest Transaction (Month/Day/Year)
06/16/2026
6. Individual or Joint/Group Filing (Check Applicable Line)
XForm filed by One Reporting Person
Form filed by More than One Reporting Person
4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year)2A. Deemed Execution Date, if any (Month/Day/Year)3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4)
CodeVAmount(A) or (D)Price
Ordinary Shares, par value $0.01 per share06/16/2026P20,000A$7.8995(1)756,000D
Ordinary Shares, par value $0.01 per share80,000IBy Manatee Equity Fund LLC(2)
Ordinary Shares, par value $0.01 per share52,000IBy Spouse
Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year)3A. Deemed Execution Date, if any (Month/Day/Year)4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 6. Date Exercisable and Expiration Date (Month/Day/Year)7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4)
CodeV(A)(D)Date ExercisableExpiration DateTitleAmount or Number of Shares
Explanation of Responses:
1. The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $7.8600 to $7.9312, inclusive. The reporting person undertakes to provide to Prothena Corp Public Ltd Co, any security holder of Prothena Corp Public Ltd Co, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnote (1) to this Form 4.
2. The reporting person disclaims beneficial ownership of these securities except to the extent of his pecuniary interest therein.
Reid E. Buchanan by POA from William P. Scully06/18/2026
** Signature of Reporting PersonDate
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)

FAQ

What insider transaction did PRTA shareholder William P. Scully report?

William P. Scully reported an open-market purchase of 20,000 Prothena ordinary shares. The trade took place on June 16, 2026 at a weighted average price of $7.8995 per share, reflecting a net increase in his directly held position.

At what price did William P. Scully buy PRTA shares in this Form 4?

Scully bought 20,000 PRTA ordinary shares at a weighted average price of $7.8995. The filing notes multiple trades executed between $7.8600 and $7.9312 per share, with full trade-by-trade details available upon request from the company or regulators.

How many PRTA shares does William P. Scully hold after this transaction?

Following the reported purchase, Scully directly holds 756,000 Prothena ordinary shares. The Form 4 also lists 52,000 shares held indirectly by his spouse and 80,000 shares held by Manatee Equity Fund LLC, subject to a disclaimer of beneficial ownership beyond his pecuniary interest.

Does the PRTA Form 4 disclose any indirect holdings for William P. Scully?

Yes. The filing lists 52,000 Prothena ordinary shares held indirectly by Scully’s spouse and 80,000 shares held by Manatee Equity Fund LLC. Scully disclaims beneficial ownership of these securities except to the extent of his pecuniary interest in the respective entities.

What does the weighted average price mean in William P. Scully’s PRTA trade?

The weighted average price of $7.8995 reflects multiple trades combined into one reported figure. According to the filing, individual purchases occurred at prices from $7.8600 to $7.9312 per share, and detailed breakdowns are available from Prothena or the SEC staff upon request.