Prothena holder Scully buys 50,000 PRTA shares

PROTHENA CORP PUBLIC LTD CO major shareholder William P. Scully reported an open-market purchase of 50,000 ordinary shares at a weighted average price of $9.426 per share on June 2, 2026.

Rhea-AI Filing Summary

PROTHENA CORP PUBLIC LTD CO major shareholder William P. Scully reported an open-market purchase of 50,000 ordinary shares at a weighted average price of $9.426 per share on June 2, 2026. Following this transaction, he directly holds 886,000 ordinary shares.

The filing also lists indirect holdings of 52,000 shares held by his spouse and 80,000 shares held by Manatee Equity Fund LLC. The reporting person disclaims beneficial ownership of these securities except to the extent of his pecuniary interest in them.

Insider Trade Summary

Net Buyer: 50,000 shares

Net Buy 3 txns

Insider SCULLY WILLIAM P

Role 10% Owner

Bought 50,000 shs ($471K)

Type	Security	Shares	Price	Value
Purchase	Ordinary Shares, par value $0.01 per share	50,000	$9.426	$471K
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 — 886,000 shares (Direct); Ordinary Shares, par value $0.01 per share — 80,000 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 $9.2323 to $9.4892, 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.

Key Figures

Open-market purchase: 50,000 shares Weighted average purchase price: $9.426 per share Direct holdings after transaction: 886,000 shares +2 more

5 metrics

Open-market purchase 50,000 shares Ordinary shares bought on June 2, 2026

Weighted average purchase price $9.426 per share Open-market transaction on June 2, 2026

Direct holdings after transaction 886,000 shares Ordinary shares directly owned following the purchase

Indirect holdings by spouse 52,000 shares Ordinary shares reported as held by spouse

Indirect holdings by Manatee Equity Fund LLC 80,000 shares Ordinary shares reported as held by Manatee Equity Fund LLC

Key Terms

open-market purchase, weighted average price, beneficial ownership

3 terms

open-market purchase financial

"Purchase in open market or private transaction"

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.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

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

William P. Scully reported buying 50,000 Prothena ordinary shares. The shares were purchased in an open-market transaction at a weighted average price of $9.426 per share, increasing his direct holdings to 886,000 ordinary shares after the transaction.

At what price did William P. Scully buy PRTA shares on June 2, 2026?

Scully’s reported purchase used a weighted average price of $9.426 per share. The filing notes the shares were bought in multiple trades between $9.2323 and $9.4892, with the average price of $9.426 disclosed in the transaction details.

How many PRTA shares does William P. Scully hold directly after this Form 4?

After the reported purchase, Scully directly holds 886,000 Prothena shares. This figure reflects his direct ownership of ordinary shares following the 50,000-share open-market acquisition reported for the June 2, 2026 transaction.

What indirect PRTA share holdings related to William P. Scully are disclosed?

The filing lists 52,000 shares held by his spouse and 80,000 by Manatee Equity Fund LLC. These are reported as indirect holdings, and Scully disclaims beneficial ownership except to the extent of his pecuniary interest in those securities.

Does William P. Scully claim full beneficial ownership of all reported PRTA shares?

No, Scully disclaims full beneficial ownership of certain indirectly held shares. He states he disclaims beneficial ownership of those securities except to the extent of his pecuniary interest, which typically limits his economic claim on the indirectly held positions.

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

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Accepted by SEC EDGAR 06/03/2026 - 12:41 PM Learn about SEC filing dates

SEC Form 4

FORM 4

UNITED 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)

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
06/02/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form 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)
			Code	V	Amount	(A) or (D)	Price
Ordinary Shares, par value $0.01 per share	06/02/2026		P		50,000	A	$9.426(1)	886,000	D
Ordinary Shares, par value $0.01 per share								80,000	I	By Manatee Equity Fund LLC(2)
Ordinary Shares, par value $0.01 per share								52,000	I	By 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)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount 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 $9.2323 to $9.4892, 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. Scully	06/03/2026
	** Signature of Reporting Person	Date
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)