Prothena (PRTA) Chief Accounting Officer awarded stock option for 150,000 shares

Rhea-AI Filing Summary

PROTHENA CORP PUBLIC LTD CO reported that Chief Accounting Officer Karin L. Walker acquired a stock option covering 150,000 shares of the company’s stock. This option was reported as a grant or award acquisition in a Form 4 insider filing.

According to the vesting terms, 25% of the 150,000 shares subject to the option will vest and become exercisable on March 3, 2027. The remaining portion will vest in 1/48th increments in equal monthly installments on each monthly anniversary after that date, conditioned on Ms. Walker’s continued employment with the company on each vesting date.

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

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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^*

Walker Karin L

(Last) (First) (Middle)

C/O PROTHENA BIOSCIENCES INC

1800 SIERRA POINT PARKWAY

(Street)

BRISBANE CA 94005

(City) (State) (Zip)

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

3. Date of Earliest Transaction (Month/Day/Year)
03/03/2026

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

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 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

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
Stock Option (Right to Buy)	$9.36	03/03/2026		A		150,000		(1)	03/03/2036	Ordinary Shares	150,000	$0	150,000	D

Explanation of Responses:

1. The shares subject to the option will vest and become exercisable as to 25% of the total number of shares subject to the option on March 3, 2027, and with respect to 1/48th of the total number of shares subject to the option in successive, equal monthly installments on each monthly anniversary thereafter, subject to the Reporting Person's continued employment with the Issuer on each such vesting date.

	/s/ Michael J. Malecek, as Attorney-in-Fact for Karin L. Walker	03/05/2026
	** 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.

FAQ

What insider transaction did PROTHENA (PRTA) report for Karin L. Walker?

PROTHENA reported that Chief Accounting Officer Karin L. Walker received a stock option grant covering 150,000 shares. The Form 4 classifies this as a grant, award, or other acquisition of a derivative security with direct ownership reported after the transaction.

How many shares are covered by Karin L. Walker’s new stock option at PROTHENA (PRTA)?

The stock option granted to Karin L. Walker covers 150,000 shares of PROTHENA’s stock. After the transaction, the total number of derivative shares reported following the grant is also 150,000, reflecting this newly awarded option position.

What is the vesting schedule for Karin L. Walker’s PROTHENA (PRTA) stock option?

The option vests 25% of the total shares on March 3, 2027. The remaining shares vest in 1/48th of the total number in equal monthly installments on each monthly anniversary thereafter, subject to Ms. Walker’s continued employment on each vesting date.

What role does Karin L. Walker hold at PROTHENA (PRTA) in this Form 4 filing?

In this Form 4, Karin L. Walker is identified as an officer of PROTHENA, serving as Chief Accounting Officer. She is not listed as a director or ten percent owner, and the reported stock option is held with direct ownership status.

Is the PROTHENA (PRTA) stock option grant to Karin L. Walker a buy or an acquisition?

The transaction is classified as an acquisition through a grant or award, not an open-market buy. The Form 4 uses transaction code “A” and describes it as a grant, award, or other acquisition of a derivative security rather than a purchase in the market.

What conditions affect vesting of Karin L. Walker’s PROTHENA (PRTA) option?

Vesting of the option is conditioned on Karin L. Walker’s continued employment with PROTHENA on each vesting date. Both the initial 25% vesting on March 3, 2027, and the subsequent monthly 1/48th installments require ongoing employment for shares to become exercisable.