UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 Securities registered pursuant to Section 12(b) of the Act: FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934. For the quarterly period ended September 30, 2024 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934. For the transition period from to . Commission File No. 001-36276 ULTRAGENYX PHARMACEUTICAL INC. (Exact name of registrant as ...