Sec Form 4 Filing - BAY CITY CAPITAL LLC @ HYPERION THERAPEUTICS INC - 2013-05-17

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 BAY CITY CAPITAL LLC 2. Issuer Name and Ticker or Trading Symbol HYPERION THERAPEUTICS INC [ HPTX] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 750 BATTERY STREET, SUITE 400 3. Date of Earliest Transaction (MM/DD/YY) 05/17/2013 (Street) SAN FRANCISCO, CA94111 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ 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 05/17/2013 S 127,034 D $ 22.69 2,279,995 D ( 1 ) ( 2 ) ( 4 ) Common Stock 05/17/2013 S 2,421 D $ 22.69 43,444 D ( 1 ) ( 3 ) ( 4 ) Common Stock 05/20/2013 S 1,963 D $ 22.24 2,278,032 D ( 1 ) ( 2 ) ( 5 ) Common Stock 05/20/2013 S 37 D $ 22.24 43,407 D ( 1 ) ( 3 ) ( 5 )

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

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other BAY CITY CAPITAL LLC 750 BATTERY STREET SUITE 400 SAN FRANCISCO, CA94111 X Bay City Capital Management V LLC C/O BAY CITY CAPITAL LLC 750 BATTERY STREET, SUITE 400 SAN FRANCISCO, CA94111 X Bay City Capital Fund V, L.P. C/O BAY CITY CAPITAL LLC 750 BATTERY STREET, SUITE 400 SAN FRANCISCO, CA94111 X Bay City Capital Fund V Co-Investment Fund, L.P. C/O BAY CITY CAPITAL LLC 750 BATTERY STREET, SUITE 400 SAN FRANCISCO, CA94111 X Signatures /s/ Fred Craves 05/21/2013 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Bay City Capital LLC, a Delaware limited liability company ("BCC"), Bay City Capital Management V LLC, a Delaware limited liability company ("Management V"), Bay City Capital Fund V, L.P., a Delaware limited partnership ("Fund V"), and Bay City Capital Fund V Co-Investment Fund, L.P., a Delaware limited partnership ("Co-Investment V") are deemed to be a "group" for the purposes of Section 13(d) under the Securities Exchange Act of 1934. Management V is the general partner of Fund V and Co-Investment V and has sole voting and dispositive power with respect to the securities held by Fund V and Co-Investment V. BCC, the manager of Management V, is also an advisor to Fund V and Co-Investment V and has sole voting and dispositive power with respect to the securities held by Fund V and Co-Investment V. ( 2 )Represents securities held by Fund V, including indirect interests of BCC and Management V. BCC and Manangement V each disclaim beneficial ownership with respect to these securities, except to the extent of their pecuniary interest therein. ( 3 )Represents securities held by Co-Investment V, including indirect interests of BCC and Management V. BCC and Manangement V each disclaim beneficial ownership with respect to these securities, except to the extent of their pecuniary interest therein. ( 4 )This transaction was executed in multiple trades at prices ranging from $22.60 to $22.96. The price reported above reflects the weighted average sale price. The reporting persons hereby undertake to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. ( 5 )This transaction was executed in multiple trades at prices ranging from $22.00 to $22.32. The price reported above reflects the weighted average sale price. The reporting persons hereby undertake to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

Remarks: Signed by Fred Craves, Managing Director of Bay City Capital LLC for itself; for and on behalf of Bay City Capital Management V LLC in its capacity as manager thereof; and for and on behalf of Bay City Capital Fund V, L.P. and Bay City Capital Fund V Co-Investment Fund, L.P. in its capacity as manager of Bay City Capital Management V LLC, the general partner of Bay City Capital Fund V, L.P. and Bay City Capital Fund V Co-Investment Fund, L.P.

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