Sec Form 4 Filing - AGARWAL SUNIL @ Ultragenyx Pharmaceutical Inc. - 2015-08-19

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 Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person AGARWAL SUNIL 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 Medical Officer (Last) (First) (Middle) C/O ULTRAGENYX PHARMACEUTICAL INC., 60 LEVERONI COURT 3. Date of Earliest Transaction (MM/DD/YY) 08/19/2015 (Street) NOVATO, CA94949 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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 08/19/2015 F 5,480 ( 1 ) D $ 116.99 23,920 ( 2 ) D Common Stock 08/20/2015 S( 3 ) 3,370 D $ 112.1892 ( 4 ) 20,550 ( 2 ) D Common Stock 08/20/2015 S( 3 ) 3,650 D $ 112.7284 ( 5 ) 16,900 ( 2 ) D Common Stock 08/20/2015 M 10,000 A $ 55.88 26,900 ( 2 ) D Common Stock 08/20/2015 S( 3 ) 724 D $ 107.302 ( 6 ) 26,176 ( 2 ) D Common Stock 08/20/2015 S( 3 ) 1,471 D $ 108.9801 ( 7 ) 24,705 ( 2 ) D Common Stock 08/20/2015 S( 3 ) 4,875 D $ 110.3961 ( 8 ) 19,830 ( 2 ) D Common Stock 08/20/2015 S( 3 ) 2,000 D $ 111.214 ( 9 ) 17,830 ( 2 ) D Common Stock 08/20/2015 S( 3 ) 930 D $ 111.9035 ( 10 ) 16,900 ( 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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 7. Title and Amount of Underlying Securities (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) $ 55.88 08/20/2015 M 10,000 ( 11 ) 08/18/2024 Common Stock 10,000 $ 0 140,000 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other AGARWAL SUNIL C/O ULTRAGENYX PHARMACEUTICAL INC. 60 LEVERONI COURT NOVATO, CA94949 Chief Medical Officer Signatures /s/ Sunil Agarwal 08/21/2015 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Represents shares surrendered to the Issuer by the Reporting Person to pay required tax withholdings due upon vesting of Restricted Stock Units granted to the Reporting Person under the Issuers 2014 Incentive Plan. The shares surrendered were valued based on the closing price of the Issuers common stock on the vesting date. ( 2 )Includes previously reported shares of common stock underlying Restricted Stock Units granted to the Reporting Person, which are subject to certain vesting conditions. ( 3 )The sales reported on this Form 4 were effected pursuant to a trading plan adopted pursuant to Rule 10b5-1 under the Securities Exchange Act of 1934, as amended. ( 4 )The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $111.9100 to $112.4500 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. ( 5 )The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $112.4600 to $113.3800 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. ( 6 )The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $107.1103 to $107.5100 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. ( 7 )The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $108.6900 to $109.6700 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. ( 8 )The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $109.7367 to $110.6900 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. ( 9 )The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $110.7600 to $111.7000 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. ( 10 )The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $111.8800 to $111.9100 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. ( 11 )1/4th of the shares underlying the option vested on August 19, 2015, and then 1/48th of the underlying shares will vest monthly thereafter, provided the Reporting Person has not terminated services with the Issuer.

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).

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