Prothena CAO exercises 15,000 RSUs, surrenders shares

On July 28, 2026, Prothena Corp Public Ltd Co Chief Accounting Officer Karin L Walker exercised 15,000 restricted stock units into 15,000 ordinary shares, then disposed of 15,000 shares back to the issuer at $8.56 per share.

Rhea-AI Filing Summary

On July 28, 2026, Prothena Corp Public Ltd Co Chief Accounting Officer Karin L Walker exercised 15,000 restricted stock units into 15,000 ordinary shares, then disposed of 15,000 shares back to the issuer at $8.56 per share. These 15,000 RSUs, part of a 25,000-unit grant made on July 28, 2025, became fully vested on the one-year anniversary; the remaining 10,000 RSUs from that grant continue to be subject to vesting.

Insider Trade Summary

15,000 shares exercised/converted

Exercise 3 txns

Insider Walker Karin L

Role Chief Accounting Officer

Type	Security	Shares	Price	Value
Exercise	Restricted Stock Units F2, F1, F3	15,000	$0.00	$0.00
Exercise	Ordinary Shares, par value $0.01 per share F1	15,000	--	--
Disposition	Ordinary Shares, par value $0.01 per share	15,000	$8.56	$128K

Holdings After Transaction: Restricted Stock Units — 0 contracts (Direct); Ordinary Shares, par value $0.01 per share — 10,000 shares (Direct)

Footnotes (3)

1. F1. Each restricted stock unit ("RSU") represents the contingent right to receive one share of the Issuer's Ordinary Shares upon vesting.
2. F2. These RSUs reported in Table II were granted to the Reporting Person on July 28, 2025 as part of an aggregate award of 25,000 RSUs and initially reported in Table I of the Form 4 filed on July 30, 2025, because they were solely settleable in shares at the time of grant. These RSUs are being moved to Table II as of this Form 4.
3. F3. These RSUs reported in Table II are fully vested as of July 28, 2026 (the one-year anniversary of the grant date). The remainder of the 25,000 RSUs reported in Table I (10,000 RSUs) are subject to vesting.

Key Figures

RSUs converted: 15,000 units Shares disposed to issuer: 15,000 shares Disposition price: $8.56 per share +3 more

6 metrics

RSUs converted 15,000 units Restricted stock units exercised into ordinary shares on July 28, 2026

Shares disposed to issuer 15,000 shares Ordinary shares disposed to issuer at $8.56 per share on July 28, 2026

Disposition price $8.56 per share Per-share price for disposition to issuer of ordinary shares

Aggregate RSU grant 25,000 RSUs Restricted stock unit award granted on July 28, 2025 to Karin L Walker

RSUs remaining subject to vesting 10,000 RSUs Portion of the 25,000 RSU grant that remains subject to vesting after July 28, 2026

RSU vesting date July 28, 2026 One-year anniversary of grant; date when 15,000 RSUs became fully vested

Key Terms

Restricted Stock Units, contingent right, Disposition to issuer

3 terms

Restricted Stock Units financial

"Each restricted stock unit ("RSU") represents the contingent right to receive one share"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

contingent right financial

"represents the contingent right to receive one share of the Issuer's Ordinary Shares"

Disposition to issuer financial

"transaction_code_description: "Disposition to issuer" for 15,000 ordinary shares"

FAQ

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

What insider transaction did Prothena (PRTA) report for Karin L Walker on July 28, 2026?

On July 28, 2026, Chief Accounting Officer Karin L Walker exercised 15,000 RSUs into 15,000 ordinary shares, then disposed of 15,000 shares to the issuer at $8.56 per share. The transaction reflects an RSU vesting and immediate disposition to the company.

How many RSUs were involved in the latest Prothena (PRTA) Form 4 for Karin L Walker?

The Form 4 reports activity on 15,000 restricted stock units, which were exercised into ordinary shares. These RSUs are part of an aggregate 25,000 RSU grant, leaving 10,000 RSUs from that grant still subject to vesting after July 28, 2026.

What price was associated with Karin L Walker’s share disposition in Prothena (PRTA)?

Karin L Walker disposed of 15,000 ordinary shares to the issuer at $8.56 per share. This transaction is coded as a “Disposition to issuer” rather than an open-market sale, and involves the shares received from the RSU exercise the same day.

When were Karin L Walker’s Prothena (PRTA) RSUs granted and when did they fully vest?

The RSUs were granted on July 28, 2025 as part of a 25,000 RSU award. The 15,000 RSUs reported here became fully vested on July 28, 2026, the one-year anniversary of the grant date, triggering their conversion into ordinary shares.

How many Prothena (PRTA) RSUs remain unvested for Karin L Walker from the reported grant?

From the original 25,000 RSU grant to Karin L Walker, 10,000 RSUs remain subject to vesting. The Form 4 notes that the 15,000 RSUs reported are fully vested, while the remaining portion continues to follow its vesting schedule.

What does each restricted stock unit represent in Prothena (PRTA)’s Form 4 for Karin L Walker?

Each restricted stock unit (RSU) represents a contingent right to receive one ordinary share of Prothena upon vesting. This means the holder receives one share for each RSU that successfully vests according to the award’s terms.

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

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Available on EDGAR 07/30/2026 - 08:34 PM Accepted by SEC EDGAR 07/30/2026 - 08:34 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^*

Walker Karin L

(Last) (First) (Middle)

C/O PROTHENA BIOSCIENCES INC

1800 SIERRA POINT PARKWAY

(Street)

BRISBANE CALIFORNIA 94005

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
07/28/2026

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	07/28/2026		M		15,000	A	(1)	25,000	D
Ordinary Shares, par value $0.01 per share	07/28/2026		D		15,000	D	$8.56	10,000	D

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
Restricted Stock Units(2)	(1)	07/28/2026		M			15,000	(3)	(3)	Ordinary Shares	15,000	$0	0	D

Explanation of Responses:

1. Each restricted stock unit ("RSU") represents the contingent right to receive one share of the Issuer's Ordinary Shares upon vesting.

2. These RSUs reported in Table II were granted to the Reporting Person on July 28, 2025 as part of an aggregate award of 25,000 RSUs and initially reported in Table I of the Form 4 filed on July 30, 2025, because they were solely settleable in shares at the time of grant. These RSUs are being moved to Table II as of this Form 4.

3. These RSUs reported in Table II are fully vested as of July 28, 2026 (the one-year anniversary of the grant date). The remainder of the 25,000 RSUs reported in Table I (10,000 RSUs) are subject to vesting.

	/s/ Michael J. Isaacs, as Attorney-in-Fact for Karin L. Walker	07/30/2026
	** 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)