[Form 4] PROTHENA CORP PUBLIC LTD CO Insider Trading Activity

Rhea-AI Filing Summary

Prothena Corp Public Ltd Co director Daniel G. Welch received a grant of stock options on Ordinary Shares covering 27,000 shares at an exercise price of $9.76 per share. These options vest 100% on the earlier of the first anniversary of the May 15, 2026 grant date or the company’s 2027 annual general meeting, assuming he continues to serve as a director through that date. Following this grant, his reported derivative holdings in this option series total 27,000 shares, and the filing shows no related sales or exercises.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider WELCH DANIEL G

Role null

Type	Security	Shares	Price	Value
Grant/Award	Stock Option (Right to Buy)	27,000	$0.00	--

Holdings After Transaction: Stock Option (Right to Buy) — 27,000 shares (Direct, null)

Footnotes (1)

1. [object Object]

Key Figures

Option grant size: 27,000 shares Exercise price: $9.76 per share Post-grant derivative holdings: 27,000 options +3 more

6 metrics

Option grant size 27,000 shares Stock Option (Right to Buy) granted to director on May 15, 2026

Exercise price $9.76 per share Conversion or exercise price of granted stock options

Post-grant derivative holdings 27,000 options Total derivative securities following this transaction

Vesting condition 100% cliff vest Earlier of first anniversary of grant or 2027 AGM, with continuous service

Option expiration May 15, 2036 Expiration date of the granted stock options

Transaction code A (grant/award acquisition) Indicates compensatory acquisition, not open-market trade

Key Terms

Stock Option (Right to Buy), Ordinary Shares, exercise price, expiration date, +1 more

5 terms

Stock Option (Right to Buy) financial

"security_title: "Stock Option (Right to Buy)""

Ordinary Shares financial

"underlying_security_title: "Ordinary Shares""

Ordinary shares are a type of ownership stake in a company, giving shareholders a right to participate in the company’s profits and decision-making through voting. They are similar to owning a piece of a business, and their value can rise or fall based on the company's performance. Investors buy ordinary shares to potentially earn dividends and benefit from the company's growth over time.

exercise price financial

"conversion_or_exercise_price: "9.7600""

The exercise price is the fixed amount at which you can buy or sell an asset, like a stock, when using an options contract. It matters because it helps determine whether exercising the option will be profitable or not, depending on the current market price. Think of it as the set price you agree on today to buy or sell later.

expiration date financial

"expiration_date: "2036-05-15T00:00:00.000Z""

The expiration date is the deadline after which a financial contract, such as an option or a futures agreement, is no longer valid or can be exercised. It matters to investors because it determines the timeframe during which they can take action or benefit from the contract, similar to how a coupon or a food item has a limited period of usefulness. Once the expiration date passes, the contract loses its value or ability to be used.

continuous service as a director financial

"assuming continuous service as a director until such vesting date"

Form 4 Insider Transactions: What Each Field Means →

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^*

WELCH DANIEL G

(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)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
05/15/2026

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

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)	$9.76	05/15/2026		A		27,000		(1)	05/15/2036	Ordinary Shares	27,000	$0	27,000	D

Explanation of Responses:

1. The shares subject to the option will vest and become exercisable as to 100% of the total number of shares subject to the option on the earlier of the first anniversary of the grant date or the day of the annual general meeting in 2027 of the Issuer's shareholders, assuming continuous service as a director until such vesting date.

	/s/ Michael J. Malecek, as Attorney-in-Fact for Daniel G. Welch	05/15/2026
	** 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)