Sec Form 4 Filing - ROOT JONATHAN D @ OncoMed Pharmaceuticals Inc - 2019-04-23

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 ROOT JONATHAN D 2. Issuer Name and Ticker or Trading Symbol OncoMed Pharmaceuticals Inc [ OMED] 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 ONCOMED PHARMACEUTICALS, INC., 800 CHESAPEAKE DRIVE 3. Date of Earliest Transaction (MM/DD/YY) 04/23/2019 (Street) REDWOOD CITY, CA94063 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 04/23/2019 U 121,020 D 0 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

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other ROOT JONATHAN D C/O ONCOMED PHARMACEUTICALS, INC. 800 CHESAPEAKE DRIVE REDWOOD CITY, CA94063 X Signatures /s/ Alicia Hager, Attorney-in-Fact for Jonathan D. Root 04/23/2019 Signature of Reporting Person Date

Explanation of Responses:

( 1 )On April 23, 2019, pursuant to the Agreement and Plan of Merger and Reorganization (the "Merger Agreement"), dated as of December 5, 2018, by and among Mereo Biopharma Group PLC ("Mereo"), Mereo US Holdings Inc., Mereo Mergerco One Inc. ("Merger Sub") and the Issuer, Merger Sub merged with and into the Issuer, with the Issuer surviving as an indirect wholly-owned subsidiary of Mereo (the "Merger"). Pursuant to the Merger, the Issuer's stockholders received the right to receive (i) a certain number of American Depositary Shares, each representing five ordinary shares, 0.003 pounds par value per share, of Mereo and (ii) one contingent value right, which represents the contractual right to receive contingent payments if specified milestones are achieved within agreed time periods, subject to and in accordance with the CVR Agreement, dated April 23, 2019, by and among Computershare Inc. and Mereo (the "Merger Consideration") for each share of the Issuer's stock that they own. ( 2 )(Continued from footnote 1) Pursuant to the Merger, the Reporting Person disposed of all shares of Issuer common stock beneficially owned by it, and received the Merger Consideration for each share of Issuer common stock.

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