Ultragenyx (RARE) CAO disposes shares in RSU tax-related transactions

Rhea-AI Filing Summary

Ultragenyx Pharmaceutical Inc. senior vice president and chief accounting officer Theodore Alan Huizenga reported two common stock transactions. He completed an open-market sale of 1,632 shares at a weighted average price of $22.80 per share, primarily to cover required tax withholdings from vesting restricted stock units (RSUs).

In a related move, he also disposed of 148 shares at $23.39 per share through share surrender to satisfy additional tax obligations tied to RSU vesting. Following these tax-related and open-market transactions, he directly owned a total of 50,302 shares of Ultragenyx common stock, which includes previously reported unvested RSUs subject to vesting conditions.

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

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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 CA 94949

(City) (State) (Zip)

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

3. Date of Earliest Transaction (Month/Day/Year)
03/02/2026

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

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

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

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	03/02/2026		F		148(1)	D	$23.39	50,302	D
Common Stock	03/02/2026		S		1,632(2)	D	$22.8(3)	48,670(4)	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 surrendered to the Issuer by the Reporting Person to pay required tax withholdings due to the vesting of RSUs.

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

3. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $22.54 to $23.11 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range

4. 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	03/03/2026
	** 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).
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FAQ

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

Ultragenyx reported that Theodore Huizenga executed an open-market sale of 1,632 common shares and a separate 148-share disposition. Both transactions were tied to covering required tax withholdings from vesting restricted stock units, according to the disclosed footnotes.

How many Ultragenyx (RARE) shares did the CAO sell in the open market?

The chief accounting officer sold 1,632 Ultragenyx common shares in an open-market transaction. The filing states a weighted average sale price of $22.80 per share, with individual trades executed between $22.54 and $23.11 inclusive, as detailed in the footnote.

Were Ultragenyx (RARE) insider share sales related to tax withholdings?

Yes. The filing explains that both the 1,632-share sale and the 148-share disposition were made to pay required tax withholdings. These obligations arose from the vesting of restricted stock units previously granted to the reporting executive.

What does the 148-share Ultragenyx (RARE) transaction represent?

The 148-share transaction represents shares surrendered or disposed of to satisfy tax liabilities from RSU vesting. The code F indicates payment of tax obligations by delivering securities directly, rather than a standard open-market sale initiated for investment purposes.

How many Ultragenyx (RARE) shares does Theodore Huizenga own after these transactions?

After the reported transactions, Theodore Huizenga directly owned 50,302 Ultragenyx common shares. This total includes previously reported RSU-based shares that remain subject to vesting conditions, as specified in the ownership footnote to the Form 4 filing.

What price range applied to the Ultragenyx (RARE) insider’s 1,632-share sale?

The 1,632-share sale was executed at multiple prices, with a weighted average of $22.80 per share. According to the footnote, individual trade prices ranged from $22.54 to $23.11, and detailed breakdown information is available upon request.