X0306 4 2022-09-15 0 0001559053 PROTHENA CORP PUBLIC LTD CO PRTA 0001854126 Garren Hideki C/O PROTHENA BIOSCIENCES INC 331 OYSTER POINT BOULEVARD SOUTH SAN FRANCISCO CA 94080 0 1 0 0 Chief Medical Officer Ordinary Shares, par value $0.01 per share 2022-09-15 4 M 0 4000 24.9 A 4000 D Ordinary Shares, par value $0.01 per share 2022-09-15 4 S 0 4000 30.00 D 0 D Stock Option (Right to Buy) 24.9 2022-09-15 4 M 0 4000 0 D 2031-04-05 Ordinary Shares 4000 234000 D The transactions reported in the Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person. 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 5, 2022 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, as attorney-in-fact for Hideki Garren 2022-09-16