Sec Form 4 Filing - Zago Wagner M. @ PROTHENA CORP PUBLIC LTD CO - 2021-02-12

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

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, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Zago Wagner M. 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 Scientific Officer (Last) (First) (Middle) C/O PROTHENA BIOSCIENCES INC, 331 OYSTER POINT BOULEVARD 3. Date of Earliest Transaction (MM/DD/YY) 02/12/2021 (Street) SOUTH SAN FRANCISCO, CA94080 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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 02/12/2021 M( 1 ) 7,560 A $ 6.41 7,560 D Ordinary Shares, par value $0.01 per share 02/12/2021 S( 1 ) 7,560 D $ 17.07 0 D Ordinary Shares, par value $0.01 per share 02/12/2021 M( 1 ) 18,750 A $ 13.53 18,750 D Ordinary Shares, par value $0.01 per share 02/12/2021 S( 1 ) 18,750 D $ 20.0004 ( 2 ) 0 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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following R eported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: 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) $ 6.41 02/12/2021 M( 1 ) 7,560 ( 3 ) 01/29/2023 Ordinary Shares 7,560 $ 0 7,540 D Stock Option (Right to Buy) $ 13.53 02/12/2021 M( 1 ) 18,750 ( 4 ) 02/27/2029 Ordinary Shares 18,750 $ 0 31,250 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Zago Wagner M. C/O PROTHENA BIOSCIENCES INC 331 OYSTER POINT BOULEVARD SOUTH SAN FRANCISCO, CA94080 Chief Scientific Officer Signatures /s/ Michael Malecek, as Attorney in Fact for Wagner M. Zago 02/17/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The sales reported in the Form 4 was effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person. ( 2 )The transaction was executed in multiple trades in prices ranging from $20.00 to $20.04, inclusive. The price reported in Column 4 above reflects the weighted average sale price. The reporting person hereby undertakes to provide to the Securities and Exchange Commission staff, the Issuer, or a security holder of the Issuer, upon request, full information regarding the number of shares sold at each respective price within the range set forth in this footnote. ( 3 )The original grant was for 36,000 shares, of which 28,460 shares have been exercised and sold. The remaining shares underlying the option (7,540 shares) are fully vested and exercisable as of the date hereof. ( 4 )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 February 27, 2020 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.

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).

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