Sec Form 3 Filing - Li Yvonne @ OncoMed Pharmaceuticals Inc - 2018-03-16

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 Li Yvonne 2. Issuer Name and Ticker or Trading Symbol OncoMed Pharmaceuticals Inc [ OMED] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) See Remarks (Last) (First) (Middle) C/O ONCOMED PHARMACEUTICALS, INC., 800 CHESAPEAKE DRIVE 3. Date of Earliest Transaction (MM/DD/YY) 03/16/2018 (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 64,952 ( 1 ) 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) $ 3.42 ( 2 ) 12/04/2018 Common Stock 1,017 D Stock Option (Right to Buy) $ 8.55 ( 2 ) 03/14/2023 Common Stock 15,571 D Stock Option (Right to Buy) $ 17 ( 2 ) 07/16/2023 Common Stock 5,000 D Stock Option (Right to Buy) $ 21.18 ( 3 ) 12/17/2024 Common Stock 35,000 D Stock Option (Right to Buy) $ 21.43 ( 4 ) 12/26/2025 Common Stock 30,000 D Stock Option (Right to Buy) $ 7.66 ( 5 ) 01/02/2027 Common Stock 45,000 D Stock Option (Right to Buy) $ 3.73 ( 6 ) 04/22/2027 Common Stock 50,000 D Stock Option (Right to Buy) $ 4.36 ( 7 ) 10/06/2027 Common Stock 26,666 D Stock Option (Right to Buy) $ 3.98 ( 8 ) 01/03/2028 Common Stock 55,000 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Li Yvonne C/O ONCOMED PHARMACEUTICALS, INC. 800 CHESAPEAKE DRIVE REDWOOD CITY, CA94063 See Remarks Signatures /s/ Alicia J. Hager, Attorney-in-Fact for Yvonne Li 03/20/2018 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Includes 45,834 Restricted Stock Units ("RSUs"). The Reporting Person is entitled to receive one (1) share of common stock for each one (1) RSU upon the vesting thereof. ( 2 )The option is fully vested and exercisable. ( 3 )The option vests with respect to 1/48 of the shares subject thereto on each monthly anniversary of December 18, 2014, subject to the Reporting Person's continued employment or service relationship with the Issuer on each such vesting date. ( 4 )The option vests with respect to 1/48 of the shares subject thereto on each monthly anniversary of December 27, 2015, subject to the Reporting Person's continued employment or service relationship with the Issuer on each such vesting date. ( 5 )The option vests with respect to 1/48 of the shares subject thereto on each monthly anniversary of January 3, 2017, subject to the Reporting Person's continued employment or service relationship with the Issuer on each such vesting date. ( 6 )The option vests with respect to 1/48 of the shares subject thereto on each monthly anniversary of April 23, 2017, subject to the Reporting Person's continued employment or service relationship with the Issuer on each such vesting date. ( 7 )The option vests with respect to 1/48 of the shares subject thereto on each monthly anniversary of October 7, 2017, subject to the Reporting Person's continued employment or service relationship with the Issuer on each such vesting date. ( 8 )The option vests with respect to 1/48 of the shares subject thereto on each monthly anniversary of January 4, 2018, subject to the Reporting Person's continued employment or service relationship with the Issuer on each such vesting date.

Remarks: Vice President, Finance, Controller and Administration

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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