RARE Ultragenyx Pharmaceutical Inc

FORM 4 [ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).         
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES                                                                                   
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Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940                       

1. Name and Address of Reporting Person * Aliski William	2. Issuer Name and Ticker or Trading Symbol Ultragenyx Pharmaceutical Inc. [ RARE ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director                    _____ 10% Owner _____ Officer (give title below)    _____ Other (specify below)
(Last)          (First)          (Middle) C/O ULTRAGENYX PHARMACEUTICAL INC., 60 LEVERONI COURT	3. Date of Earliest Transaction (MM/DD/YYYY) 2/19/2021
(Street) NOVATO, CA 94949 (City)        (State)        (Zip)	4. If Amendment, Date Original Filed (MM/DD/YYYY)	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. Trans. Date	2A. Deemed Execution Date, if any	3. Trans. 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	2/19/2021		M		7500	A	$97.85	73204	D
Common Stock	2/19/2021		S		7500	D	$149.01 (1)	65704	D
Common Stock	2/23/2021		G		1000	D	$0.00	64704 (2)	D
Common Stock								70350	I	By trust (3)
Common Stock								10456	I	By trust (4)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	4. Trans. 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		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 of Derivative Security: 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
Stock Option (Right to Buy)	$97.85	2/19/2021		M			7500	(5)	6/18/2025	Common Stock	7500	$0.00	0	D

Explanation of Responses:
(1)	The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $149.00 to $149.15 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.
(2)	Includes previously reported shares of common stock underlying RSUs granted to the Reporting Person, which are subject to certain vesting conditions.
(3)	These shares are held in a trust for the benefit of the Reporting Person's spouse and children. The Reporting Person's spouse and nephew are trustees of the trust.
(4)	These shares are held in a grantor retained annuity trust. The Reporting Person is the trustee of the trusts.
(5)	The option vested in full on on June 9, 2016.

Reporting Owners
Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Aliski William C/O ULTRAGENYX PHARMACEUTICAL INC. 60 LEVERONI COURT NOVATO, CA 94949	X

Signatures
/s/ Karah Parschauer, attorney-in-fact		2/23/2021
**Signature of Reporting Person		Date