Sec Form 3 Filing - RiverVest Venture Fund III, L.P. @ Allakos Inc. - 2018-07-18

FORM 3 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 RiverVest Venture Fund III, L.P. 2. Issuer Name and Ticker or Trading Symbol Allakos Inc. [ ALLK] 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) 101 S. HANLEY ROAD, SUITE 1850 3. Date of Earliest Transaction (MM/DD/YY) 07/18/2018 (Street) ST. LOUIS, MO63105 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

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 Series A Preferred Stock ( 1 ) ( 1 ) ( 1 ) Common Stock 6,482,724 I See footnote ( 2 ) ( 3 ) ( 4 ) ( 5 ) Series B Preferred Stock ( 1 ) ( 1 ) ( 1 ) Common Stock 777,417 I See footnote ( 3 ) ( 4 ) ( 5 ) ( 6 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other RiverVest Venture Fund III, L.P. 101 S. HANLEY ROAD SUITE 1850 ST. LOUIS, MO63105 X RiverVest Venture Fund II (Ohio), L.P. 101 S. HANLEY ROAD SUITE 1850 ST. LOUIS, MO63105 X RiverVest Venture Fund III (Ohio), L.P. 101 S. HANLEY ROAD SUITE 1850 ST. LOUIS, MO63105 X RIVERVEST VENTURE FUND II L P 101 S. HANLEY ROAD SUITE 1850 ST. LOUIS, MO63105 X 3x5 RiverVest Fund II, L.P. 101 S. HANLEY ROAD SUITE 1850 ST. LOUIS, MO63105 X 3x5 RiverVest Fund II-B, L.P. 101 S. HANLEY ROAD SUITE 850 ST. LOUIS, MO63105 X Signatures /s/ John P. McKearn, Manager of RiverVest Venture Partners III, LLC 07/18/2018 Signature of Reporting Person Date /s/ John P. McKearn, Authorized Person of RiverVest Venture Partners II, LLC 07/18/2018 Signature of Reporting Person Date /s/ John P. McKearn, Member of RiverVest 3x5 Managers II, LLC 07/18/2018 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Each share of Series A Preferred Stock and Series B Preferred Stock shall automatically convert into Common Stock on a one-for-one basis immediately prior to the closing of the Issuer's initial public offering of common stock and has no expiration date. ( 2 )RiverVest Venture Fund II, L.P ("RiverVest II") owns 954,494 shares of Series A Preferred Stock. RiverVest Venture Fund II (Ohio), L.P. ("RiverVest (Ohio) II") owns 259,258 shares of Series A Preferred Stock. RiverVest Venture Fund III, L.P ("RiverVest III") owns 3,234,069 shares of Series A Preferred Stock. RiverVest Venture Fund III (Ohio), L.P. ("RiverVest (Ohio) III") owns 171,647 shares of Series A Preferred Stock. 3x5 RiverVest Fund II, L.P. ("3x5 II") owns 1,795,434 shares of Series A Preferred Stock. 3x5 RiverVest Fund II-B, L.P. ("3x5 II-B") owns 67,822 shares of Series A Preferred Stock. ( 3 )The shares held by RiverVest II are indirectly held by RiverVest Venture Partners II, L.P. ("RiverVest Partners II"), which is the general partner of RiverVest II. The shares held by RiverVest (Ohio) II are indirectly held by RiverVest Venture Partners II (Ohio), LLC ("RiverVest Partners (Ohio) II"), which is the general partner of RiverVest (Ohio) II. RiverVest Partners II is the sole member of RiverVest Partners (Ohio) II. RiverVest Venture Partners II, LLC is the general partner of RiverVest Partners II. John P. McKearn is an Authorized Person of RiverVest Venture Partners II, LLC and may be deemed to share dispositive voting and investment power with respect to the shares held by RiverVest II and RiverVest (Ohio) II. ( 4 )The shares held by RiverVest III are indirectly held by RiverVest Venture Partners III, L.P. ("RiverVest Partners III"), which is the general partner of RiverVest III. The shares held by RiverVest (Ohio) III are indirectly held by RiverVest Venture Partners III (Ohio), LLC ("RiverVest Partners (Ohio) III"), which is the general partner of RiverVest (Ohio) III. RiverVest Partners III is the sole member of RiverVest Partners (Ohio) III. RiverVest Venture Partners III, LLC is the general partner of RiverVest Partners III. John P. McKearn is a Manager of RiverVest Venture Partners III, LLC and may be deemed to share dispositive voting and investment power with respect to the shares held by RiverVest III and RiverVest (Ohio) III. ( 5 )The shares held by 3x5 II and 3x5 II-B are indirectly held by 3x5 RiverVest Partners II, LLC ("3x5 Partners II"), which is the general partner of 3x5 II and 3x5 II-B. RiverVest 3x5 Managers II, L.P. ("3x5 Managers II"), is a Member of 3x5 Partners II. RiverVest 3x5 Managers II, LLC is the general partner of 3x5 Managers II. John P. McKearn is a Member of RiverVest 3x5 Managers II, LLC and may be deemed to share dispositive voting and investment power with respect to the shares held by 3x5 II and 3x5 II-B. Dr. McKearn disclaims beneficial ownership of all shares held by RiverVest II, RiverVest (Ohio) II, RiverVest III, RiverVest (Ohio) III, 3x5 II and 3x5 II-B except to the extent of his pecuniary interests therein. ( 6 )RiverVest II owns 26,199 shares of Series B Preferred Stock. RiverVest (Ohio) II owns 7,116 shares of Series B Preferred Stock. RiverVest III owns 284,750 shares of Series B Preferred Stock. RiverVest (Ohio) III owns 15,112 shares of Series B Preferred Stock. 3x5 II owns 428,071 shares of Series B Preferred Stock. 3x5 II-B owns 16,169 shares of Series A Preferred Stock.

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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