PRTA · Prothena Corp Public Ltd Co

The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $8.5094 to $8.7500, inclusive. The reporting person undertakes to provide to Prothena Corp Public Ltd Co, any security holder of Prothena Corp Public Ltd Co, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnote (1) to this Form 4.

The reporting person disclaims beneficial ownership of these securities except to the extent of his pecuniary interest therein.

The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $8.5094 to $8.7500, inclusive. The reporting person undertakes to provide to Prothena Corp Public Ltd Co, any security holder of Prothena Corp Public Ltd Co, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnote (1) to this Form 4.

The transaction was effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on March 30, 2026.

The transaction was executed in multiple trades in prices ranging from $8.40 to $8.64, 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 ranges set forth in this footnote.

The transaction was effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on April 3, 2026.

The transaction was executed in multiple trades in prices ranging from $8.40 to $8.65, 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.

Each restricted stock unit ("RSU") represents the contingent right to receive one share of the Issuer's Ordinary Shares upon vesting.

These RSUs reported in Table II were granted to the Reporting Person on July 28, 2025 as part of an aggregate award of 25,000 RSUs and initially reported in Table I of the Form 4 filed on July 30, 2025, because they were solely settleable in shares at the time of grant. These RSUs are being moved to Table II as of this Form 4.

Each restricted stock unit ("RSU") represents the contingent right to receive one share of the Issuer's Ordinary Shares upon vesting.

These RSUs reported in Table II are fully vested as of July 28, 2026 (the one-year anniversary of the grant date). The remainder of the 25,000 RSUs reported in Table I (10,000 RSUs) are subject to vesting.

These RSUs reported in Table II were granted to the Reporting Person on July 28, 2025 as part of an aggregate award of 95,000 RSUs and initially reported in Table I of the Form 4 filed on July 30, 2025, because they were solely settleable in shares at the time of grant. These RSUs are being moved to Table II as of this Form 4.

Each restricted stock unit ("RSU") represents the contingent right to receive one share of the Issuer's Ordinary Shares upon vesting.

These RSUs reported in Table II are fully vested as of July 28, 2026 (the one-year anniversary of the grant date). The remainder of the 95,000 RSUs reported in Table I (38,000 RSUs) are subject to vesting.

These RSUs reported in Table II were granted to the Reporting Person on July 28, 2025 as part of an aggregate award of 130,000 RSUs and initially reported in Table I of the Form 4 filed on July 30, 2025, because they were solely settleable in shares at the time of grant. These RSUs are being moved to Table II as of this Form 4.

Each restricted stock unit ("RSU") represents the contingent right to receive one share of the Issuer's Ordinary Shares upon vesting.

These RSUs reported in Table II are fully vested as of July 28, 2026 (the one-year anniversary of the grant date). The remainder of the 130,000 RSUs reported in Table I (52,000 RSUs) are subject to vesting.

Each restricted stock unit ("RSU") represents the contingent right to receive one share of the Issuer's Ordinary Shares upon vesting.

Each restricted stock unit ("RSU") represents the contingent right to receive one share of the Issuer's Ordinary Shares upon vesting.

Each restricted stock unit ("RSU") represents the contingent right to receive one share of the Issuer's Ordinary Shares upon vesting.

These RSUs reported in Table II were granted to the Reporting Person on July 28, 2025 as part of an aggregate award of 140,000 RSUs and initially reported in Table I of the Form 4 filed on July 30, 2025, because they were solely settleable in shares at the time of grant. These RSUs are being moved to Table II as of this Form 4.

Each restricted stock unit ("RSU") represents the contingent right to receive one share of the Issuer's Ordinary Shares upon vesting.

These RSUs reported in Table II are fully vested as of July 28, 2026 (the one-year anniversary of the grant date). The remainder of the 140,000 RSUs reported in Table I (56,000 RSUs) are subject to vesting.

These RSUs reported in Table II were granted to the Reporting Person on July 28, 2025 as part of an aggregate award of 85,000 RSUs and initially reported in Table I of the Form 4 filed on July 30, 2025, because they were solely settleable in shares at the time of grant. These RSUs are being moved to Table II as of this Form 4.

Each restricted stock unit ("RSU") represents the contingent right to receive one share of the Issuer's Ordinary Shares upon vesting.

These RSUs reported in Table II are fully vested as of July 28, 2026 (the one-year anniversary of the grant date). The remainder of the 85,000 RSUs reported in Table I (34,000 RSUs) are subject to vesting.

Each restricted stock unit ("RSU") represents the contingent right to receive one share of the Issuer's Ordinary Shares upon vesting.

Each restricted stock unit ("RSU") represents the contingent right to receive one share of the Issuer's Ordinary Shares upon vesting.

These RSUs reported in Table II were granted to the Reporting Person on July 28, 2025 as part of an aggregate award of 85,000 RSUs and initially reported in Table I of the Form 4 filed on July 30, 2025, because they were solely settleable in shares at the time of grant. These RSUs are being moved to Table II as of this Form 4.

Each restricted stock unit ("RSU") represents the contingent right to receive one share of the Issuer's Ordinary Shares upon vesting.

These RSUs reported in Table II are fully vested as of July 28, 2026 (the one-year anniversary of the grant date). The remainder of the 85,000 RSUs reported in Table I (34,000 RSUs) are subject to vesting.

The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $7.8600 to $7.9312, inclusive. The reporting person undertakes to provide to Prothena Corp Public Ltd Co, any security holder of Prothena Corp Public Ltd Co, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnote (1) to this Form 4.

The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $7.8400 to $8.4300, inclusive. The reporting person undertakes to provide to Prothena Corp Public Ltd Co, any security holder of Prothena Corp Public Ltd Co, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnote (1) to this Form 4.

The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $9.1000 to $9.4097, inclusive. The reporting person undertakes to provide to Prothena Corp Public Ltd Co, any security holder of Prothena Corp Public Ltd Co, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnote (1) to this Form 4.

The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $9.2323 to $9.4892, inclusive. The reporting person undertakes to provide to Prothena Corp Public Ltd Co, any security holder of Prothena Corp Public Ltd Co, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnote (1) to this Form 4.

The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $9.5499 to $9.9750, inclusive. The reporting person undertakes to provide to Prothena Corp Public Ltd Co, any security holder of Prothena Corp Public Ltd Co, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnote (1) to this Form 4.

The shares subject to the option will vest and become exercisable as to 100% of the total number of shares subject to the option on the earlier of the first anniversary of the grant date or the day of the annual general meeting in 2027 of the Issuer's shareholders, assuming continuous service as a director until such vesting date.

The shares subject to the option will vest and become exercisable as to 100% of the total number of shares subject to the option on the earlier of the first anniversary of the grant date or the day of the annual general meeting in 2027 of the Issuer's shareholders, assuming continuous service as a director until such vesting date.

The shares subject to the option will vest and become exercisable as to 100% of the total number of shares subject to the option on the earlier of the first anniversary of the grant date or the day of the annual general meeting in 2027 of the Issuer's shareholders, assuming continuous service as a director until such vesting date.

The shares subject to the option will vest and become exercisable as to 100% of the total number of shares subject to the option on the earlier of the first anniversary of the grant date or the day of the annual general meeting in 2027 of the Issuer's shareholders, assuming continuous service as a director until such vesting date.

The shares subject to the option will vest and become exercisable as to 100% of the total number of shares subject to the option on the earlier of the first anniversary of the grant date or the day of the annual general meeting in 2027 of the Issuer's shareholders, assuming continuous service as a director until such vesting date.

The shares subject to the option will vest and become exercisable as to 100% of the total number of shares subject to the option on the earlier of the first anniversary of the grant date or the day of the annual general meeting in 2027 of the Issuer's shareholders, assuming continuous service as a director until 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 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.

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.

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.

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.

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.

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.

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.

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.