STOCK TITAN

Prothena (PRTA) 10% owner William Scully adds 37,500 shares in open-market buys

(Moderate)
(Positive)
Form Type
4

Rhea-AI Filing Summary

Prothena Corp Public Ltd Co major shareholder William P. Scully reported open-market purchases of the company’s ordinary shares on August 7, 2026. He bought 34,000 shares directly and 3,500 shares through Manatee Equity Fund LLC at a weighted average price of $8.6192 per share, with trade prices ranging from $8.5094 to $8.7500. Following these trades, he reported 790,000 shares held directly and 83,500 shares held indirectly via Manatee Equity Fund LLC, while an additional 52,000 shares are reported as held indirectly by his spouse. The filer disclaims beneficial ownership of the Manatee-held shares except to the extent of his pecuniary interest.

Positive

  • None.

Negative

  • None.
Insider SCULLY WILLIAM P
Role 10% Owner
Bought 37,500 shs ($323K)
Type Security Shares Price Value
Purchase Ordinary Shares, par value $0.01 per share F1 34,000 $8.6192 $293K
Purchase Ordinary Shares, par value $0.01 per share F1, F2 3,500 $8.6192 $30K
holding Ordinary Shares, par value $0.01 per share -- -- --
Holdings After Transaction: Ordinary Shares, par value $0.01 per share — 790,000 shares (Direct); Ordinary Shares, par value $0.01 per share — 83,500 shares (Indirect, By Manatee Equity Fund LLC); Ordinary Shares, par value $0.01 per share — 52,000 shares (Indirect, By Spouse)
Footnotes (2)
  1. F1. The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $8.5094 to $8.7500, 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. F2. The reporting person disclaims beneficial ownership of these securities except to the extent of his pecuniary interest therein.
Direct shares purchased 34,000 shares Ordinary shares bought directly on August 7, 2026
Indirect shares purchased via Manatee Equity Fund LLC 3,500 shares Ordinary shares bought indirectly on August 7, 2026
Weighted average purchase price $8.6192 per share Weighted average for trades ranging from $8.5094 to $8.7500
Direct holdings after transaction 790,000 shares Ordinary shares held directly following August 7, 2026 purchases
Indirect holdings via Manatee Equity Fund LLC after transaction 83,500 shares Ordinary shares held indirectly through Manatee Equity Fund LLC after purchases
Indirect holdings by spouse 52,000 shares Ordinary shares reported as held indirectly by spouse
Total reported shares bought 37,500 shares Sum of direct and Manatee Equity Fund LLC purchases on August 7, 2026
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 except..."
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
"Indirect ownership reported via Manatee Equity Fund LLC and by spouse."

AI-generated analysis. How Rhea-AI works. Not financial advice.

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FAQ

What insider transactions did PRTA major shareholder William P. Scully report?

William P. Scully reported open-market purchases of Prothena ordinary shares on August 7, 2026, totaling 37,500 shares. This included 34,000 shares bought directly and 3,500 shares bought indirectly through Manatee Equity Fund LLC.

At what price were the PRTA shares purchased by William P. Scully?

The reported transactions used a weighted average price of $8.6192 per share. The shares were bought in multiple trades at prices ranging from $8.5094 to $8.7500, according to the filing footnote.

How many PRTA shares does William P. Scully hold directly after these trades?

After the August 7, 2026 purchases, William P. Scully reported holding 790,000 Prothena ordinary shares directly. This figure reflects his direct ownership position immediately following the reported transactions.

Were the PRTA insider purchases made under a Rule 10b5-1 trading plan?

The Rule 10b5-1 checkbox is not marked as plan-based for these transactions. The trades are reported as open-market purchases without identifying a pre-arranged trading plan in the filing’s data.
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)
08/07/2026
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 share08/07/2026P34,000A$8.6192(1)790,000D
Ordinary Shares, par value $0.01 per share08/07/2026P3,500A$8.6192(1)83,500IBy 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 $8.5094 to $8.7500, 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. Scully08/10/2026
** 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)