X0306 4 2015-12-09 0 0001559053 Prothena Corp plc PRTA 0001564380 Kinney Gene G. C/O PROTHENA BIOSCIENCES INC 650 GATEWAY BOULEVARD SOUTH SAN FRANCISCO CA 94080 0 1 0 0 CSO & Head of R&D Ordinary Shares, par value $0.01 per share 2015-12-09 4 M 0 30000 6.41 A 32793 D Ordinary Shares, par value $0.01 per share 2015-12-09 4 S 0 8201 65.4616 D 24592 D Ordinary Shares, par value $0.01 per share 2015-12-09 4 S 0 20439 66.3724 D 4153 D Ordinary Shares, par value $0.01 per share 2015-12-09 4 S 0 1360 67.0517 D 2793 D Stock Option (right to buy) 6.41 2015-12-09 4 M 0 30000 0.00 D 2023-01-29 Ordinary Shares 30000 170000 D The sale reported in the Form 4 was effected pursuant to a Rule 10b5 1 trading plan adopted by the Reporting Person. The transaction was executed in multiple trades in prices ranging from $64.83 to $65.82, inclusive. The price reported in Column 4 above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide upon request to the SEC staff, the Issuer, or a stockholder of the Issuer, information regarding the number of shares and prices at which the transaction was effected. The transaction was executed in multiple trades in prices ranging from $65.83 to $66.82, inclusive. The price reported in Column 4 above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide upon request to the SEC staff, the Issuer, or a stockholder of the Issuer, information regarding the number of shares and prices at which the transaction was effected. The transaction was executed in multiple trades in prices ranging from $66.83 to $67.54, inclusive. The price reported in Column 4 above reflects the weighted average sale price. The Reporting Person hereby undertakes to provide upon request to the SEC staff, the Issuer, or a stockholder of the Issuer, information regarding the number of shares and prices at which the transaction was effected. 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 January 29, 2014 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/ A.W. Homan, as Attorney-in-Fact for Gene G. Kinney 2015-12-11