Prothena CFO exercises 57,000 RSUs, disposes shares

PROTHENA CORP PUBLIC LTD CO officer Nguyen Tran, Chief Strategy Officer and CFO, exercised 57,000 restricted stock units into 57,000 ordinary shares on July 28, 2026, and on the same date disposed 57,000 ordinary shares to the issuer at $8.56 per share.

Rhea-AI Filing Summary

PROTHENA CORP PUBLIC LTD CO officer Nguyen Tran, Chief Strategy Officer and CFO, exercised 57,000 restricted stock units into 57,000 ordinary shares on July 28, 2026, and on the same date disposed 57,000 ordinary shares to the issuer at $8.56 per share. These RSUs were part of a 95,000-unit award granted July 28, 2025; 38,000 RSUs from that grant remain subject to vesting.

Insider Trade Summary

57,000 shares exercised/converted

Exercise 3 txns

Insider Nguyen Tran

Role Chief Strategy Officer and CFO

Type	Security	Shares	Price	Value
Exercise	Restricted Stock Units F2, F1, F3	57,000	$0.00	$0.00
Exercise	Ordinary Shares, par value $0.01 per share F1	57,000	--	--
Disposition	Ordinary Shares, par value $0.01 per share	57,000	$8.56	$488K

Holdings After Transaction: Restricted Stock Units — 0 contracts (Direct); Ordinary Shares, par value $0.01 per share — 40,205 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 95,000 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 95,000 RSUs reported in Table I (38,000 RSUs) are subject to vesting.

Key Figures

RSUs exercised: 57,000 units Ordinary shares disposed to issuer: 57,000 shares Disposition price: $8.56 per share +2 more

5 metrics

RSUs exercised 57,000 units Restricted stock units converted into ordinary shares on July 28, 2026

Ordinary shares disposed to issuer 57,000 shares Disposition to issuer coded D on July 28, 2026

Disposition price $8.56 per share Price reported for 57,000 ordinary shares disposed to issuer

Original RSU award 95,000 units RSUs granted to Nguyen Tran on July 28, 2025

RSUs remaining unvested 38,000 units Portion of the 95,000 RSU grant still subject to vesting after July 28, 2026

Key Terms

Restricted Stock Units, disposition to issuer, contingent right to receive one share, vested

4 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.

disposition to issuer financial

"transaction code "D" with transaction_action "issuer disposition""

contingent right to receive one share financial

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

vested financial

"These RSUs reported in Table II are fully vested as of July 28, 2026"

FAQ

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

What insider equity transaction did Prothena (PRTA) report for Nguyen Tran on July 28, 2026?

Nguyen Tran exercised 57,000 restricted stock units into 57,000 ordinary shares on July 28, 2026, then disposed 57,000 ordinary shares back to the issuer at $8.56 per share, according to the Form 4.

How many restricted stock units from Nguyen Tran’s 2025 award vested at Prothena (PRTA)?

Out of a 95,000 RSU award granted July 28, 2025, 57,000 RSUs reported in this filing are fully vested as of July 28, 2026, while the remaining 38,000 RSUs are still subject to vesting conditions.

What was the per-share value for Nguyen Tran’s disposition of Prothena (PRTA) shares to the issuer?

The Form 4 reports a disposition of 57,000 ordinary shares to the issuer at $8.56 per share. This transaction is coded as a disposition to issuer (code D), not an open-market sale.

Does Nguyen Tran retain restricted stock units in Prothena (PRTA) after this Form 4 transaction?

Yes. A footnote states that 38,000 RSUs from the original 95,000 RSU grant remain subject to vesting after the 57,000 RSUs reported here vested on July 28, 2026.

What position does Nguyen Tran hold at Prothena (PRTA) in connection with this Form 4?

Nguyen Tran is identified as Prothena’s Chief Strategy Officer and Chief Financial Officer. The reported transactions involve his equity compensation, specifically restricted stock units converting into ordinary shares and a disposition to the issuer.

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

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Available on EDGAR 07/30/2026 - 08:32 PM Accepted by SEC EDGAR 07/30/2026 - 08:32 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^*

Nguyen Tran

(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 Strategy Officer and CFO

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		57,000	A	(1)	97,205	D
Ordinary Shares, par value $0.01 per share	07/28/2026		D		57,000	D	$8.56	40,205	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			57,000	(3)	(3)	Ordinary Shares	57,000	$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 95,000 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 95,000 RSUs reported in Table I (38,000 RSUs) are subject to vesting.

	/s/ Michael J. Isaacs, as Attorney-in-Fact for Tran B. Nguyen	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.
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* Form 4: SEC 1474 (03-26)