X0306 4 2021-10-12 0 0001515673 Ultragenyx Pharmaceutical Inc. RARE 0001574591 Dier Mardi C/O ULTRAGENYX PHARMACEUTICAL INC. 60 LEVERONI COURT NOVATO CA 94949 0 1 0 0 CFO & Executive Vice President Common Stock 2021-10-12 4 S 0 3477 82.79 D 42023 D Common Stock 2021-10-14 4 S 0 3261 81.16 D 38762 D Represents shares sold to pay required tax withholdings due to the vesting of Restricted Stock Units ("RSUs"). The transaction reported in this row on this Form 4 was effected pursuant to a trading plan adopted by the Reporting Person pursuant to Rule 10b5-1 under the Securities Exchange Act of 1934, as amended. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $80.55 to $81.81 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 previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions. /s/ Karah Parschauer, attorney-in-fact 2021-10-14