Prothena (NASDAQ: PRTA) ten percent owner reports direct and indirect stakes

Rhea-AI Filing Summary

PROTHENA CORP PUBLIC LTD CO insider William P. Scully filed an initial ownership report as a ten percent owner of PRTA. He reports 736,000 ordinary shares held directly, plus 80,000 shares held indirectly through Manatee Equity Fund LLC and 52,000 shares held indirectly by his spouse. A footnote states he disclaims beneficial ownership of these securities except to the extent of his pecuniary interest.

Insider Trade Summary

3 transactions reported

Mixed 3 txns

Insider SCULLY WILLIAM P

Role null

Type	Security	Shares	Price	Value
holding	Ordinary Shares, par value $0.01 per share	--	--	--
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 — 736,000 shares (Direct, null); Ordinary Shares, par value $0.01 per share — 80,000 shares (Indirect, By Manatee Equity Fund LLC)

Footnotes (1)

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Key Figures

Direct ordinary shares: 736,000 shares Indirect shares via Manatee Equity Fund LLC: 80,000 shares Indirect shares by spouse: 52,000 shares +1 more

4 metrics

Direct ordinary shares 736,000 shares Directly held ordinary shares as of the reported date

Indirect shares via Manatee Equity Fund LLC 80,000 shares Indirect ownership through Manatee Equity Fund LLC

Indirect shares by spouse 52,000 shares Indirect ownership reported as held by spouse

Ownership status Ten percent owner Reported status for Section 16 purposes on Form 3

Key Terms

ten percent owner, beneficial ownership, pecuniary interest, indirect ownership

4 terms

ten percent owner regulatory

"The Form 3 identifies William P. Scully as a ten percent owner."

beneficial ownership regulatory

"The reporting person disclaims beneficial ownership of these securities except to the extent of his pecuniary interest therein."

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

"The reporting person disclaims beneficial ownership of these securities except to the extent of his pecuniary interest therein."

indirect ownership financial

"Indirect ownership is reported through Manatee Equity Fund LLC and by spouse."

Understanding Insider Trading Forms →

SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

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:			3235-0104
Estimated average burden
hours per response:			0.5

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. Date of Event Requiring Statement (Month/Day/Year)
05/07/2026

3. Issuer Name and Ticker or Trading Symbol
PROTHENA CORP PUBLIC LTD CO [ PRTA ]

3a. Foreign Trading Symbol

5. If Amendment, Date of Original Filed (Month/Day/Year)

4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

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

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

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Ordinary Shares, par value $0.01 per share	736,000	D
Ordinary Shares, par value $0.01 per share	80,000	I	By Manatee Equity Fund LLC(1)
Ordinary Shares, par value $0.01 per share	52,000	I	By Spouse

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. The reporting person disclaims beneficial ownership of these securities except to the extent of his pecuniary interest therein.

Remarks:

Exhibit List: Exhibit 24 - Power of Attorney

	Reid E. Buchanan by POA from William P. Scully	05/14/2026
	** 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 5 (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 3: SEC 1473 (03-26)

FAQ

What does the PRTA Form 3 filed by William P. Scully show?

The Form 3 shows William P. Scully as a ten percent owner of PRTA, reporting direct and indirect holdings of ordinary shares. It is an initial ownership disclosure, not a report of new purchases or sales.

How many PROTHENA (PRTA) shares does William P. Scully hold directly?

He reports directly holding 736,000 ordinary shares of PROTHENA. This figure reflects his personal position in the issuer’s stock as of the reported date, separate from additional indirect holdings through related parties.

What indirect PRTA holdings are reported for William P. Scully?

The filing lists 80,000 ordinary shares held indirectly through Manatee Equity Fund LLC and 52,000 shares held indirectly by his spouse. These positions are reported as indirect ownership interests associated with Scully.

Does the PRTA Form 3 indicate recent insider buying or selling?

No, the Form 3 lists existing holdings rather than new transactions. The entries are classified as holdings with no buy or sell codes, serving to establish Scully’s ownership position as a ten percent owner.

What does it mean that Scully disclaims beneficial ownership of some PRTA shares?

The footnote says he disclaims beneficial ownership of the securities except to the extent of his pecuniary interest. This means he reports the positions but limits acknowledgment of true economic ownership to the portion where he has financial exposure.