UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Ultragenyx Pharmaceutical Inc.

(Exact name of Registrant as Specified in Its Charter)

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

As reported by Ultragenyx Pharmaceutical Inc. (the “Company”) in its Current Report on Form 8-K filed with the Securities and Exchange Commission (the “SEC”) on July 12, 2023 (the “Form 8-K”), the Company previously announced that Howard Horn has been appointed as the Company’s Chief Financial Officer and Executive Vice President, Corporate Strategy (“CFO and EVP, Corporate Strategy”), effective as of October 16, 2023. Mr. Horn and the Company have modified the effective date of Mr. Horn’s appointment as the Company’s CFO and EVP, Corporate Strategy from October 16, 2023 to October 9, 2023 (the “Effective Date”).

In connection with the modification to the Effective Date as described above, the Company and Mr. Horn entered into Amendment No. 1 dated September 6, 2023 (the “Offer Letter Amendment”), to the offer letter dated June 22, 2023 (the “Offer Letter”). The foregoing description of the Offer Letter Amendment is only a summary and is qualified in its entirety by reference to the full text of the Offer Letter Amendment, a copy of which is filed as Exhibit 10.1, and incorporated by reference herein.

A copy of the Offer Letter was previously filed with the SEC as Exhibit 10.1 on the Form 8-K.

Item 9.01 Financial Statements and Exhibits.

(d)Exhibits

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.