Prothena grants 190,000-share option to legal chief

Malecek Michael J reported acquisition or exercise transactions in this Form 4 filing.

Accepted by SEC EDGAR 03/05/2026 - 04:50 PM EST Learn about SEC filing dates

Rhea-AI Filing Summary

Malecek Michael J reported acquisition or exercise transactions in this Form 4 filing.

Prothena Corp Public Ltd Co granted Chief Legal Officer Michael J. Malecek a stock option covering 190,000 shares of the company’s stock. According to the award terms, 25% of the option will vest and become exercisable on March 3, 2027. The remaining shares will vest in equal monthly installments of 1/48th of the total option on each monthly anniversary thereafter, subject to his continued employment with the company on each vesting date.

Insider Trade Summary

Grant/Award: 190,000 shares

Grant/Award 1 txn

Insider Malecek Michael J

Role Chief Legal Officer

Type	Security	Shares	Price	Value
Grant/Award	Stock Option (Right to Buy)	190,000	$0.00	$0.00

Holdings After Transaction: Stock Option (Right to Buy) — 190,000 contracts (Direct)

Footnotes (1)

1. F1. 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.

FAQ

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

What insider transaction did Prothena (PRTA) report for Michael J. Malecek?

Prothena reported a grant of a stock option to Chief Legal Officer Michael J. Malecek covering 190,000 shares of company stock. This is an equity-based compensation award rather than an open-market share purchase or sale.

What type of security was granted in the latest Prothena (PRTA) Form 4?

The filing shows a Stock Option (Right to Buy) as the security granted. This option gives the reporting person the right to acquire Prothena ordinary shares, subject to the vesting schedule and other terms described in the award.

When do Michael J. Malecek’s Prothena (PRTA) stock options start vesting?

The stock options begin vesting on March 3, 2027, when 25% of the total shares under the option vest. This initial cliff vesting date marks the first time any portion of the award becomes exercisable, subject to continued employment.

How do the remaining Prothena (PRTA) stock options vest after March 3, 2027?

After 25% vests on March 3, 2027, the remaining portion vests in 1/48th monthly installments. Each monthly anniversary thereafter triggers an additional equal installment, contingent on the reporting person’s continued employment at each vesting date.

Whose employment status affects vesting of the new Prothena (PRTA) option grant?

Vesting depends on the continued employment of Michael J. Malecek with Prothena. Each vesting date, including the initial 25% on March 3, 2027 and subsequent monthly installments, requires that he remain employed by the issuer on that date.

How many Prothena (PRTA) derivative securities does Michael J. Malecek hold after this grant?

Following this transaction, the reporting person holds 190,000 derivative securities in the form of stock options. This figure represents the total number of option shares reported as beneficially owned after the grant in the Form 4 filing.

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

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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^*

Malecek Michael J

(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 Legal 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		190,000		(1)	03/03/2036	Ordinary Shares	190,000	$0	190,000	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 Malecek	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.