Prothena holder buys 27K shares at $9.47

Q: What insider transaction did PRTA ten percent owner William P. Scully report?

He reported a purchase of 27,000 ordinary shares of PRTA on September 2, 2026 in an open-market or private transaction, as shown by the Form 4 data.

Q: At what price did the insider buy PRTA shares on September 2, 2026?

The reported price is a weighted average of $9.4718 per share, with individual trades executed at prices ranging from $9.4072 to $9.6100, inclusive.

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

Following the September 2, 2026 purchase, he holds 827,000 ordinary shares directly, according to the reported post-transaction ownership.

Q: What indirect PRTA holdings are associated with William P. Scully?

Indirectly, there are 83,500 shares held through Manatee Equity Fund LLC and 52,000 shares held by his spouse. He disclaims beneficial ownership of the Manatee-held shares except to the extent of his pecuniary interest.

Q: Was the PRTA insider trade made under a Rule 10b5-1 trading plan?

No. The filing indicates no Rule 10b5-1 trading plan applies to the reported September 2, 2026 transaction.

Q: What is the approximate total value of PRTA shares purchased by the insider?

He acquired 27,000 shares at a weighted average price of $9.4718, for an approximate transaction value of about $255,700, based on the figures reported in the Form 4.

A ten percent owner of PRTA bought additional shares on September 2, 2026, increasing his direct and indirect holdings.

Accepted by SEC EDGAR 09/03/2026 - 06:23 PM EDT

Filing Impact

(Moderate)

Filing Sentiment

(Positive)How Sentiment works

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Form Type

Rhea-AI Filing Summary

PROTHENA CORP PUBLIC LTD CO (PRTA) reporting person William P. Scully, a ten percent owner, purchased 27,000 ordinary shares on September 2, 2026 in open-market or private transactions at a weighted average price of $9.4718 per share, with individual prices ranging from $9.4072 to $9.6100.

After this purchase, he holds 827,000 shares directly, plus indirect holdings of 83,500 shares through Manatee Equity Fund LLC (for which he disclaims beneficial ownership except to the extent of his pecuniary interest) and 52,000 shares held by his spouse. No Rule 10b5-1 trading plan is reported.

Insider Trade Summary

Net Buyer: 27,000 shares

Net Buy 1 txn

Insider SCULLY WILLIAM P

Role 10% Owner

Bought 27,000 shs ($256K)

Type	Security	Shares	Price	Value
Purchase	Ordinary Shares, par value $0.01 per share ^F1	27,000	$9.4718	$256K
Holding	Ordinary Shares, par value $0.01 per share ^F2	--	--	--
Holding	Ordinary Shares, par value $0.01 per share	--	--	--

Holdings After Transaction: Ordinary Shares, par value $0.01 per share — 827,000 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)

F1. The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $9.4072 to $9.6100, 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.
F2. The reporting person disclaims beneficial ownership of these securities except to the extent of his pecuniary interest therein.

Key Figures

Shares purchased: 27,000 shares Weighted average purchase price: $9.4718 per share Price range of purchases: $9.4072–$9.6100 per share +4 more

7 metrics

Shares purchased 27,000 shares Ordinary shares bought on September 2, 2026

Weighted average purchase price $9.4718 per share Open-market or private purchase on September 2, 2026

Price range of purchases $9.4072–$9.6100 per share Multiple transactions included in the reported weighted average price

Direct holdings after transaction 827,000 shares Ordinary shares held directly after September 2, 2026 purchase

Indirect holdings via Manatee Equity Fund LLC 83,500 shares Indirect ownership; beneficial ownership disclaimed except for pecuniary interest

Indirect holdings by spouse 52,000 shares Ordinary shares held indirectly through spouse

Approximate transaction value About $255,700 27,000 shares at $9.4718 weighted average price

Key Terms

weighted average price, beneficial ownership, pecuniary interest

3 terms

weighted average price financial

"The price reported ... 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 regulatory

"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."

FAQ

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

What insider transaction did PRTA ten percent owner William P. Scully report?

He reported a purchase of 27,000 ordinary shares of PRTA on September 2, 2026 in an open-market or private transaction, as shown by the Form 4 data.

At what price did the insider buy PRTA shares on September 2, 2026?

The reported price is a weighted average of $9.4718 per share, with individual trades executed at prices ranging from $9.4072 to $9.6100, inclusive.

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

Following the September 2, 2026 purchase, he holds 827,000 ordinary shares directly, according to the reported post-transaction ownership.

What indirect PRTA holdings are associated with William P. Scully?

Indirectly, there are 83,500 shares held through Manatee Equity Fund LLC and 52,000 shares held by his spouse. He disclaims beneficial ownership of the Manatee-held shares except to the extent of his pecuniary interest.

Was the PRTA insider trade made under a Rule 10b5-1 trading plan?

No. The filing indicates no Rule 10b5-1 trading plan applies to the reported September 2, 2026 transaction.

What is the approximate total value of PRTA shares purchased by the insider?

He acquired 27,000 shares at a weighted average price of $9.4718, for an approximate transaction value of about $255,700, based on the figures reported in the Form 4.

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

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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)
09/02/2026

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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Ordinary Shares, par value $0.01 per share	09/02/2026		P		27,000	A	$9.4718⁽¹⁾	827,000	D
Ordinary Shares, par value $0.01 per share								83,500	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)
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)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)

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 $9.4072 to $9.6100, 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	09/03/2026
	** 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)

Source: View Original Filing on SEC EDGAR