Form 4: RARE CFO sale tied to RSU vesting; 98,227 owned

Rhea-AI Filing Summary

Ultragenyx Pharmaceutical (RARE) insider activity: The company’s Chief Financial Officer reported a sale of common stock on 10/13/2025. The filing shows 7,942 shares were sold at $31.51 per share.

According to the explanation, these shares were sold to pay required tax withholdings related to the vesting of restricted stock units (RSUs). Following the transaction, the reporting person beneficially owned 98,227 shares. The ownership is listed as direct.

The filing notes that the remaining amount includes previously reported shares underlying RSUs that are subject to vesting conditions.

Insider Trade Summary

Net Seller: 7,942 shares ($250,252)

Net Sell 1 txn

Insider Horn Howard

Role Chief Financial Officer

Sold 7,942 shs ($250K)

Type	Security	Shares	Price	Value
Sale	Common Stock	7,942	$31.51	$250K

Holdings After Transaction: Common Stock — 98,227 shares (Direct)

Footnotes (1)

1. Represents shares sold to pay required tax withholdings due to the vesting of RSUs. Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.

Form 4 Insider Transactions: What Each Field Means →

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).

1. Name and Address of Reporting Person^*

Horn Howard

(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)
	Chief Financial Officer

3. Date of Earliest Transaction (Month/Day/Year)
10/13/2025

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	10/13/2025		S		7,942(1)	D	$31.51	98,227(2)	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 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	10/14/2025
	** 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.

FAQ

What did Ultragenyx (RARE) disclose in this Form 4?

The CFO reported selling 7,942 shares of common stock on 10/13/2025 at $31.51 per share.

Why were the RARE shares sold by the CFO?

The sale was to pay required tax withholdings due to the vesting of RSUs.

How many Ultragenyx shares does the CFO own after the transaction?

The filing reports 98,227 shares beneficially owned following the transaction.

What is the relationship of the reporting person to Ultragenyx (RARE)?

The reporting person is an officer, serving as Chief Financial Officer.

Is the ownership direct or indirect after the reported sale?

The ownership form is listed as direct.

Do the reported holdings include unvested RSUs?

Yes. The amount includes previously reported shares underlying RSUs subject to vesting conditions.