Material Event (Form 8-K)

On August 7, 2026, Ultragenyx Pharmaceutical Inc. (the "Company") and Baylor Research Institute ("BRI") entered into a settlement agreement with Esjay Pharma Private Limited and Esjay Pharma LLC (collectively, "Esjay") resolving patent litigation related to the Company's DOJOLVI® (triheptanoin) oral liquid. The litigation, which was filed in the United States District Court for the District of New Jersey, resulted from submission by Esjay of an Abbreviated New Drug Application ("ANDA") to the U.S. Food and Drug Administration seeking approval to market a generic version of DOJOLVI in the United States. Under the terms of the settlement agreement, the Company will grant Esjay a non-exclusive, royalty-free license to market its generic version of DOJOLVI beginning January 1, 2033, which would be extended to July 1, 2033 if pediatric exclusivity is granted for DOJOLVI, subject to certain conditions and exceptions customary for agreements of this type. Similar patent litigation brought by the Company against other ANDA filers related to DOJOLVI remains pending in the U.S. District Court for the District of New Jersey.

As required by law, the settlement agreement will be submitted to the U.S. Federal Trade Commission and the U.S. Department of Justice. The description of the settlement agreement contained herein does not purport to be complete.