RARE · Ultragenyx Pharmaceutical Inc.

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

Includes 646 shares acquired under the Company's Amended and Restated Employee Stock Purchase Place on April 30, 2026

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

Award of Restricted Stock Units ("RSUs") under the Company's 2023 Incentive Plan. The RSUs shall vest in full on the earlier of (i) the Company's next Annual Meeting of Stockholders or (ii) May 14, 2027.

The option shall vest in full on the earlier of (i) the Company's next Annual Meeting of Stockholders or (ii) May 14, 2027.

The option shall vest in full on the earlier of (i) the Company's next Annual Meeting of Stockholders or (ii) May 14, 2027.

The option shall vest in full on the earlier of (i) the Company's next Annual Meeting of Stockholders or (ii) May 14, 2027.

Award of Restricted Stock Units ("RSUs") under the Company's 2023 Incentive Plan. The RSUs shall vest in full on the earlier of (i) the Company's next Annual Meeting of Stockholders or (ii) May 14, 2027.

Award of Restricted Stock Units ("RSUs") under the Company's 2023 Incentive Plan. The RSUs shall vest in full on the earlier of (i) the Company's next Annual Meeting of Stockholders or (ii) May 14, 2027.

The option shall vest in full on the earlier of (i) the Company's next Annual Meeting of Stockholders or (ii) May 14, 2027.

The option shall vest in full on the earlier of (i) the Company's next Annual Meeting of Stockholders or (ii) May 14, 2027.

The option shall vest in full on the earlier of (i) the Company's next Annual Meeting of Stockholders or (ii) May 14, 2027.

Award of Restricted Stock Units ("RSUs") under the Company's 2023 Incentive Plan. The RSUs shall vest in full on the earlier of (i) the Company's next Annual Meeting of Stockholders or (ii) May 14, 2027.

Award of Restricted Stock Units ("RSUs") under the Company's 2023 Incentive Plan. The RSUs shall vest in full on the earlier of (i) the Company's next Annual Meeting of Stockholders or (ii) May 14, 2027.

The option shall vest in full on the earlier of (i) the Company's next Annual Meeting of Stockholders or (ii) May 14, 2027.

Award of Restricted Stock Units ("RSUs") under the Company's 2023 Incentive Plan. The RSUs shall vest in full on the earlier of (i) the Company's next Annual Meeting of Stockholders or (ii) May 14, 2027.

Award of Restricted Stock Units ("RSUs") under the Company's 2023 Incentive Plan. The RSUs shall vest in full on the earlier of (i) the Company's next Annual Meeting of Stockholders or (ii) May 14, 2027.

Represents shares sold to pay required tax withholdings due to the vesting of RSUs.

Includes 558 shares acquired under the Company's Amended and Restated Employee Stock Purchase Plan on April 30, 2026

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

Award of Restricted Stock Units ("RSUs") under the Company's 2023 Incentive Plan. The RSUs shall vest with respect to 1/4th of the underlying shares on each anniversary of the grant date, such that the RSUs are fully vested on the fourth anniversary of the grant date

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

On the first anniversary of the grant date of the option (the "Option Anniversary Date"), 1/4th of the shares initially subject to the option shall vest; thereafter, 1/48th of the shares initially subject to the option shall vest on each month as measured from the Option Anniversary Date.

Award of Restricted Stock Units ("RSUs") under the Company's 2023 Incentive Plan. The RSUs shall vest with respect to 1/4th of the underlying shares on each anniversary of the grant date, such that the RSUs are fully vested on the fourth anniversary of the grant date

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

Award of Restricted Stock Units ("RSUs") under the Company's 2023 Incentive Plan. The RSUs shall vest with respect to 1/4th of the underlying shares on each anniversary of the grant date, such that the RSUs are fully vested on the fourth anniversary of the grant date

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

On the first anniversary of the grant date of the option (the "Option Anniversary Date"), 1/4th of the shares initially subject to the option shall vest; thereafter, 1/48th of the shares initially subject to the option shall vest on each month as measured from the Option Anniversary Date.

Award of Restricted Stock Units ("RSUs") under the Company's 2023 Incentive Plan. The RSUs shall vest with respect to 1/4th of the underlying shares on each anniversary of the grant date, such that the RSUs are fully vested on the fourth anniversary of the grant date

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

On the first anniversary of the grant date of the option (the "Option Anniversary Date"), 1/4th of the shares initially subject to the option shall vest; thereafter, 1/48th of the shares initially subject to the option shall vest on each month as measured from the Option Anniversary Date.

Award of Restricted Stock Units ("RSUs") under the Company's 2023 Incentive Plan. The RSUs shall vest with respect to 1/4th of the underlying shares on each anniversary of the grant date, such that the RSUs are fully vested on the fourth anniversary of the grant date

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

Award of Restricted Stock Units ("RSUs") under the Company's 2023 Incentive Plan. The RSUs shall vest with respect to 1/4th of the underlying shares on each anniversary of the grant date, such that the RSUs are fully vested on the fourth anniversary of the grant date

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

On the first anniversary of the grant date of the option (the "Option Anniversary Date"), 1/4th of the shares initially subject to the option shall vest; thereafter, 1/48th of the shares initially subject to the option shall vest on each month as measured from the Option Anniversary Date.

On the first anniversary of the grant date of the option (the "Option Anniversary Date"), 1/4th of the shares initially subject to the option shall vest; thereafter, 1/48th of the shares initially subject to the option shall vest on each month as measured from the Option Anniversary Date.

Award of Restricted Stock Units ("RSUs") under the Company's 2023 Incentive Plan. The RSUs shall vest with respect to 1/4th of the underlying shares on each anniversary of the grant date, such that the RSUs are fully vested on the fourth anniversary of the grant date

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

Award of Restricted Stock Units ("RSUs") under the Company's 2023 Incentive Plan. The RSUs shall vest with respect to 1/4th of the underlying shares on each anniversary of the grant date, such that the RSUs are fully vested on the fourth anniversary of the grant date

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

On the first anniversary of the grant date of the option (the "Option Anniversary Date"), 1/4th of the shares initially subject to the option shall vest; thereafter, 1/48th of the shares initially subject to the option shall vest on each month as measured from the Option Anniversary Date.

On the first anniversary of the grant date of the option (the "Option Anniversary Date"), 1/4th of the shares initially subject to the option shall vest; thereafter, 1/48th of the shares initially subject to the option shall vest on each month as measured from the Option Anniversary Date.

On the first anniversary of the grant date of the option (the "Option Anniversary Date"), 1/4th of the shares initially subject to the option shall vest; thereafter, 1/48th of the shares initially subject to the option shall vest on each month as measured from the Option Anniversary Date.

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

Represents shares sold to pay required tax withholdings due to the vesting of RSUs.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $22.54 to $23.11 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, 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 range

Includes 73 shares acquired under the Company's Amended and Restated Employee Stock Purchase Plan on October 31, 2025

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

Represents shares surrendered to the Issuer by the Reporting Person to pay required tax withholdings due to the vesting of RSUs.

Represents shares sold to pay required tax withholdings due to the vesting of RSUs.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $22.54 to $23.11 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, 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 range

Represents shares sold to pay required tax withholdings due to the vesting of RSUs.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $22.54 to $23.11 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, 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 range

Includes 490 shares acquired under the Company's Amended and Restated Employee Stock Purchase Plan on April 30, 2025.

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

Represents shares sold to pay required tax withholdings due to the vesting of RSUs.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $22.54 to $23.11 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, 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 range

Includes 157 shares acquired on October 30, 2025 under the Company's Amended and Restated Employee Stock Purchase Plan

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

Represents shares surrendered to the Issuer by the Reporting Person to pay required tax withholdings due to the vesting of RSUs.

Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.