X0306 4 2016-09-19 0 0001559053 Prothena Corp plc PRTA 0001559422 Walker Karin L C/O PROTHENA BIOSCIENCES INC 650 GATEWAY BOULEVARD SOUTH SAN FRANCISCO CA 94080 0 1 0 0 See Remarks Ordinary Shares, par value $0.01 per share 2016-09-19 4 M 0 7000 9.75 A 7000 D Ordinary Shares, par value $0.01 per share 2016-09-19 4 S 0 4300 60.0006 D 2700 D Ordinary Shares, par value $0.01 per share 2016-09-19 4 S 0 2700 61.8305 D 0 D Ordinary Shares, par value $0.01 per share 2016-09-19 4 M 0 5000 27.81 A 5000 D Ordinary Shares, par value $0.01 per share 2016-09-19 4 S 0 500 60.01 D 4500 D Ordinary Shares, par value $0.01 per share 2016-09-19 4 S 0 4500 61.8342 D 0 D Stock Option (right to buy) 9.75 2016-09-19 4 M 0 7000 0.00 D 2023-06-02 Ordinary Shares 7000 11000 D Stock Option (right to buy) 27.81 2016-09-19 4 M 0 5000 0.00 D 2025-03-11 Ordinary Shares 5000 19000 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 $60.00 to $60.025, 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 $61.79 to $61.885, 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 $60.00 to $60.025, 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 $61.79 to $61.885, 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 May 20, 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 or service relationship with the Issuer on each such vesting date. 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 11, 2016 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. Controller, Chief Accounting Officer and Head of Accounting /s/ Arthur W. Homan, as Attorney-in-Fact for Karin L. Walker 2016-09-21