RARE: Material agreement

Item 1.01 Entry into a Material Definitive Agreement. On October 6, 2026, Ultragenyx Pharmaceutical Inc. (the “Company”) entered into an asset purchase agreement (the “PRV Asset Purchase Agreement”), pursuant to which the Company agreed to sell a Rare Pediatric Disease Priority Review Voucher (“PRV”) to the buyer. The Company was awarded the PRV by the U.S. Food and Drug Administration (“FDA”) on August 19, 2026 upon approval of GENGLYCOS™ (pariglasgene brecaparvovec-opnr), also known as DTX401, in adult and pediatric patients eight years and older with glycogen storage disease type Ia (GSDIa). Pursuant to the PRV Asset Purchase Agreement, the buyer agreed to pay the Company $210 million, payable in cash, upon the closing of the transaction. Pursuant to the terms of a patent license agreement with the U.S. Department of Health (the “NIH”) dated December 10, 2018, 20% of the gross proceeds from the sale of the PRV will be payable by the Company to the NIH after the closing of the transaction. The PRV Asset Purchase Agreement contains customary representations, warranties, covenants, and indemnification provisions subject to certain limitations. The transaction remains subject to customary closing conditions, including the expiration or termination of the applicable waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976. The foregoing description of the PRV Asset Purchase Agreement does not purport to be complete and is qualified in its entirety by the full text of the PRV Asset Purchase Agreement, a copy of which will be filed with the Company’s Annual Report on Form 10-K for the year ended December 31, 2026. SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on it