Ultragenyx officer sells 161 shares to cover taxes

Ultragenyx’s chief accounting officer reports a small tax-withholding sale tied to RSU vesting, with direct holdings remaining above 69,000 shares.

Rhea-AI Filing Summary

Ultragenyx Pharmaceutical Inc. (RARE) reports that Theodore Alan Huizenga, its SVP and Chief Accounting Officer, reported a sale of 161 shares of common stock on September 3, 2026 at $13.99 per share. The shares were sold to pay required tax withholdings from vesting RSUs, and he now holds 69,146 shares directly, including 396 shares acquired under the company’s Amended and Restated Employee Stock Purchase Plan and previously reported unvested RSUs. No Rule 10b5-1 trading plan is reported.

Insider Trade Summary

Net Seller: 161 shares

Net Sell 1 txn

Insider Huizenga Theodore Alan

Role SVP, Chief Accounting Officer

Sold 161 shs ($2K)

Type	Security	Shares	Price	Value
Sale	Common Stock F1, F2, F3	161	$13.99	$2K

Holdings After Transaction: Common Stock — 69,146 shares (Direct)

Footnotes (3)

1. F1. Represents shares sold to pay required tax withholdings due to the vesting of RSUs.
2. F2. Includes 396 shares acquired under the Company's Amended and Restated Employee Stock Purchase Place on April 30, 2026.
3. F3. Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

Key Figures

Shares sold: 161 shares Sale price per share: $13.99 per share Approximate transaction value: $2,252 +2 more

5 metrics

Shares sold 161 shares Common stock sale reported for September 3, 2026

Sale price per share $13.99 per share Price for the 161 shares sold on September 3, 2026

Approximate transaction value $2,252 161 shares sold at $13.99 per share to cover tax withholdings

Shares owned after transaction 69,146 shares Direct holdings of Theodore Alan Huizenga after the September 3, 2026 sale

ESPP shares included 396 shares Shares acquired under the Amended and Restated Employee Stock Purchase Plan on April 30, 2026

Key Terms

Restricted Stock Units, Amended and Restated Employee Stock Purchase Plan, tax withholdings

3 terms

Restricted Stock Units financial

"due to the vesting of RSUs"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

Amended and Restated Employee Stock Purchase Plan financial

"acquired under the Company's Amended and Restated Employee Stock Purchase Place"

tax withholdings financial

"shares sold to pay required tax withholdings due to the vesting"

FAQ

What insider transaction did Ultragenyx (RARE) report for Theodore Alan Huizenga?

Ultragenyx reported that SVP and Chief Accounting Officer Theodore Alan Huizenga sold 161 shares of common stock on September 3, 2026 to cover tax withholdings related to vesting RSUs.

At what price were the Ultragenyx (RARE) shares sold in this Form 4?

The filing states the 161 shares were sold at a price of $13.99 per share on September 3, 2026, characterized as a sale in the open market or a private transaction.

Why did the Ultragenyx (RARE) insider sell 161 shares?

A footnote explains that the 161 shares were sold to pay required tax withholdings due to the vesting of Restricted Stock Units (RSUs), rather than as a discretionary portfolio transaction.

How many Ultragenyx (RARE) shares does Theodore Alan Huizenga hold after the reported sale?

After the transaction, Theodore Alan Huizenga directly holds 69,146 shares of Ultragenyx common stock, which includes 396 shares acquired under the company’s Amended and Restated Employee Stock Purchase Plan and previously reported RSUs subject to vesting.

Was the Ultragenyx (RARE) insider trade made under a Rule 10b5-1 plan?

No. The Form 4 indicates no Rule 10b5-1 trading plan is reported for this transaction, and the footnotes do not refer to any pre-arranged trading plan.

What additional share acquisitions are noted for the Ultragenyx (RARE) officer?

A footnote states that the reported post-transaction holdings include 396 shares acquired under Ultragenyx’s Amended and Restated Employee Stock Purchase Plan on April 30, 2026, along with previously reported RSUs subject to vesting.

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Available on EDGAR 09/08/2026 - 12:30 PM Accepted by SEC EDGAR 09/08/2026 - 12:29 PM Learn about SEC filing dates

SEC Form 4

FORM 4

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

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Huizenga Theodore Alan

(Last) (First) (Middle)

C/O ULTRAGENYX PHARMACEUTICAL INC.

60 LEVERONI COURT

(Street)

NOVATO CALIFORNIA 94949

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
Ultragenyx Pharmaceutical Inc. [ RARE ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	SVP, Chief Accounting Officer

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
09/03/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	09/03/2026		S		161(1)	D	$13.99	69,146(2)(3)	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. Represents shares sold to pay required tax withholdings due to the vesting of RSUs.

2. Includes 396 shares acquired under the Company's Amended and Restated Employee Stock Purchase Place on April 30, 2026.

3. 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	09/08/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)