Michael J. Isaacs - 08 Jun 2026 Form 3 Insider Report for PROTHENA CORP PUBLIC LTD CO (PRTA)

Reporting relationship: General Counsel & Company Sec.
Issuer ticker: PRTA
Reported as of: 08 Jun 2026
Net transaction value: $0
SEC form: 3
Accepted by SEC: 12 Jun 2026, 16:18:54 UTC
Source filing: View source filing
Reporting owner signature: /s/ Michael J. Isaacs

Key filing fact

Michael J. Isaacs filed Form 3 for PROTHENA CORP PUBLIC LTD CO (PRTA) on 12 Jun 2026.

Key facts

This page summarizes Michael J. Isaacs's Form 3 filing for PROTHENA CORP PUBLIC LTD CO (PRTA).
0 reported transactions and 8 derivative rows are listed below.
Accepted by SEC: 12 Jun 2026, 16:18.

Change

No earlier filing in this sequence is available for direct comparison.
Current net transaction value: $0.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Official SEC source

Ownership activity is grounded in SEC Form 3 disclosures.

View source filing

Reporting Owners (1)

CIK 0002127815 Primary reporting owner

Isaacs Michael John

Relationship: General Counsel & Company Sec.
Address: C/O PROTHENA BIOSCIENCES INC., 1800 SIERRA POINT PARKWAY, BRISBANE
Signature: /s/ Michael J. Isaacs
Signature date: 12 Jun 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

PRTA holding

Ordinary Shares, par value $0.01 per share

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after: 48,825
Date: 08 Jun 2026
Ownership: Direct

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

PRTA holding Derivative

Stock Option (Right to Buy)

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
Date: 08 Jun 2026
Ownership: Direct
Underlying class: Ordinary Shares
Underlying amount: 17,500
Exercise price: $10.99
Footnotes: F1

PRTA holding Derivative

Stock Option (Right to Buy)

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
Date: 08 Jun 2026
Ownership: Direct
Underlying class: Ordinary Shares
Underlying amount: 10,000
Exercise price: $22.60
Footnotes: F1

PRTA holding Derivative

Stock Option (Right to Buy)

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
Date: 08 Jun 2026
Ownership: Direct
Underlying class: Ordinary Shares
Underlying amount: 8,250
Exercise price: $32.45
Footnotes: F1

PRTA holding Derivative

Stock Option (Right to Buy)

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
Date: 08 Jun 2026
Ownership: Direct
Underlying class: Ordinary Shares
Underlying amount: 8,800
Exercise price: $52.97
Footnotes: F2

PRTA holding Derivative

Stock Option (Right to Buy)

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
Date: 08 Jun 2026
Ownership: Direct
Underlying class: Ordinary Shares
Underlying amount: 12,000
Exercise price: $30.30
Footnotes: F3

PRTA holding Derivative

Stock Option (Right to Buy)

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
Date: 08 Jun 2026
Ownership: Direct
Underlying class: Ordinary Shares
Underlying amount: 8,612
Exercise price: $14.95
Footnotes: F4

PRTA holding Derivative

Stock Option (Right to Buy)

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
Date: 08 Jun 2026
Ownership: Direct
Underlying class: Ordinary Shares
Underlying amount: 37,500
Exercise price: $9.36
Footnotes: F5

PRTA holding Derivative

Stock Option (Right to Buy)

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
Date: 08 Jun 2026
Ownership: Direct
Underlying class: Ordinary Shares
Underlying amount: 50,000
Exercise price: $10.50
Footnotes: F6

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Explanation of responses 6 footnotes

Footnote F1

The option is fully vested.

Footnote F2

The shares subject to the option vested and became exercisable as to 25% of the total number of shares subject to the option on March 2, 2024, and vest and become exercisable 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.

Footnote F3

The shares subject to the option vested and became exercisable as to 25% of the total number of shares subject to the option on February 27, 2025, and vest and become exercisable 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.

Footnote F4

The shares subject to the option vested and became exercisable as to 25% of the total number of shares subject to the option on March 5, 2026, and vest and become exercisable 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.

Footnote F5

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.

Footnote F6

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 April 10, 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.

SEC remarks

Exhibit List: Exhibit 24 - Power of Attorney

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