Prothena COO exercises 78,000 RSUs, returns shares to issuer

PROTHENA CORP PUBLIC LTD CO reported that Chief Operating Officer Brandon S. Smith exercised 78,000 restricted stock units into the same number of ordinary shares on July 28, 2026, then disposed of 78,000 shares back to the issuer at $8.56 per share.

Rhea-AI Filing Summary

PROTHENA CORP PUBLIC LTD CO reported that Chief Operating Officer Brandon S. Smith exercised 78,000 restricted stock units into the same number of ordinary shares on July 28, 2026, then disposed of 78,000 shares back to the issuer at $8.56 per share. These RSUs were part of a 130,000-unit grant from July 28, 2025, of which 52,000 RSUs remain subject to vesting.

Insider Trade Summary

78,000 shares exercised/converted

Exercise 3 txns

Insider Smith Brandon S.

Role Chief Operating Officer

Type	Security	Shares	Price	Value
Exercise	Restricted Stock Units F2, F1, F3	78,000	$0.00	$0.00
Exercise	Ordinary Shares, par value $0.01 per share F1	78,000	--	--
Disposition	Ordinary Shares, par value $0.01 per share	78,000	$8.56	$668K

Holdings After Transaction: Restricted Stock Units — 0 contracts (Direct); Ordinary Shares, par value $0.01 per share — 52,000 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 130,000 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 130,000 RSUs reported in Table I (52,000 RSUs) are subject to vesting.

Key Figures

RSUs exercised: 78,000 units Shares disposed to issuer: 78,000 shares Disposition price: $8.56 per share +2 more

5 metrics

RSUs exercised 78,000 units Restricted stock units converted into ordinary shares on July 28, 2026

Shares disposed to issuer 78,000 shares Ordinary shares returned to issuer at $8.56 per share on July 28, 2026

Disposition price $8.56 per share Price for 78,000 ordinary shares disposed of to issuer

Original RSU grant 130,000 units Aggregate RSU award granted on July 28, 2025

Unvested RSUs remaining 52,000 units Portion of the 130,000 RSU grant still subject to vesting

Key Terms

Restricted Stock Units, disposition to issuer, contingent right, fully 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_description": "Disposition to issuer""

contingent right financial

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

fully 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 transaction did Prothena (PRTA) report for Brandon S. Smith?

Prothena reported that COO Brandon S. Smith exercised 78,000 RSUs into ordinary shares and then disposed of 78,000 shares back to the issuer at $8.56 per share on July 28, 2026, resulting in no net change from this RSU block.

How many restricted stock units did Prothena (PRTA) grant to Brandon S. Smith in 2025?

Brandon S. Smith received an aggregate award of 130,000 restricted stock units on July 28, 2025. Of this grant, 78,000 RSUs have fully vested and were exercised on July 28, 2026, while 52,000 RSUs remain subject to vesting conditions.

At what price were Brandon S. Smith’s Prothena (PRTA) shares disposed of to the issuer?

The 78,000 ordinary shares that Brandon S. Smith disposed of to the issuer were priced at $8.56 per share. This transaction followed the same-day exercise of 78,000 RSUs into ordinary shares on July 28, 2026.

What portion of Brandon S. Smith’s Prothena (PRTA) RSU grant remains unvested?

Out of Brandon S. Smith’s 130,000 RSU grant, 52,000 RSUs remain subject to vesting. The other 78,000 RSUs fully vested by July 28, 2026 and were exercised into ordinary shares on that date before being disposed of to the issuer.

When did Brandon S. Smith’s Prothena (PRTA) RSUs vest and get exercised?

The 78,000 RSUs vested on July 28, 2026, one year after the July 28, 2025 grant date. On the same date, they were exercised into 78,000 ordinary shares, which were then disposed of back to the issuer at $8.56 per share.

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

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Available on EDGAR 07/30/2026 - 08:33 PM Accepted by SEC EDGAR 07/30/2026 - 08:33 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^*

Smith Brandon S.

(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 Operating 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		78,000	A	(1)	130,000	D
Ordinary Shares, par value $0.01 per share	07/28/2026		D		78,000	D	$8.56	52,000	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			78,000	(3)	(3)	Ordinary Shares	78,000	$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 130,000 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 130,000 RSUs reported in Table I (52,000 RSUs) are subject to vesting.

	/s/ Michael J. Isaacs, as Attorney-in-Fact for Brandon S. Smith	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)