Sec Form 3 Filing - Presidio Management Group X LLC @ eFFECTOR Therapeutics, Inc. - 2021-08-25

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 Presidio Management Group X LLC 2. Issuer Name and Ticker or Trading Symbol eFFECTOR Therapeutics, Inc. [ EFTR] 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) 1460 EL CAMINO REAL, 3. Date of Earliest Transaction (MM/DD/YY) 08/25/2021 (Street) MENLO PARK, CA94025 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 3,981,940 ( 1 ) ( 2 ) I Directly owned by USVP X ( 4 ) Common Stock 127,389 ( 1 ) ( 3 ) I Directly owned by AFF X ( 4 ) Common Stock 690,688 ( 5 ) I Directly owned by USVP X ( 4 ) Common Stock 22,097 ( 5 ) I Directly owned by AFF X ( 4 )

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 Earn-out Right ( 6 ) $ 0 ( 6 ) ( 6 ) ( 6 ) Common Stock 586,573 ( 6 ) I Directly held by USVP X ( 4 ) Earn-out Right ( 6 ) $ 0 ( 6 ) ( 6 ) ( 6 ) Common Stock 18,765 ( 6 ) I Directly held by AFF X ( 4 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Presidio Management Group X LLC 1460 EL CAMINO REAL MENLO PARK, CA94025 X US VENTURE PARTNERS X LP 1460 EL CAMINO REAL, STE 100 MENLO PARK, CA94025 X USVP X AFFILIATES LP 1460 EL CAMINO REAL, STE 100 MENLO PARK, CA94025 X Tansey Casey M 1460 EL CAMINO REAL SUITE 100 MENLO PARK, CA94025 X Signatures Dale Holladay, Attorney in Fact for each Reporting Person 08/27/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )On August 25, 2021, pursuant to that certain Agreement and Plan of Merger, dated as of May 26, 2021 (the "Merger Agreement"), by and among the issuer (f/k/a Locust Walk Acquisition Corp.), Locust Walk Merger Sub, Inc. ("Merger Sub"), and eFFECTOR Therapeutics, Inc. ("Old eFFECTOR"), Merger Sub merged with and into Old eFFECTOR with Old eFFECTOR surviving as a wholly owned subsidiary of the Issuer (the "Merger"). Upon consummation of the Merger (the "Effective Time"), each issued and outstanding share of common stock of Old eFFECTOR was automatically cancelled and converted into approximately 0.09657 (the "Exchange Ratio") shares of common stock of the Issuer. ( 2 )The 3,981,940 shares of common stock held by USVP X represents the conversion of 25,015,222 shares of Series A Preferred, 9,197,554 shares of Series B Preferred and 7,020,627 shares of Series C Preferred of Old eFFECTOR into an aggregate of 41,233,403 shares of Old eFFECTOR common stock and the subsequent cancellation and conversion of such shares into shares of common stock of the Issuer in the Merger at the Exchange Ratio. ( 3 )The 127,389 shares of common stock held by AFF X represents the conversion of 800,281 shares of Series A Preferred, 294,246 shares of Series B Preferred and 224,604 shares of Series C Preferred of Old eFFECTOR into an aggregate of 1,319,131 shares of Old eFFECTOR common stock and the subsequent cancellation and conversion of such shares into shares of common stock of the Issuer in the Merger at the Exchange Ratio. ( 4 )Presidio Management Group X, L.L.C. ("PMG X"), the general partner of each of U.S. Venture Partners X, L.P. ("USVP X") and USVP X Affiliates L.P. ("AFF X") (together, the "USVP X Funds"), has sole voting and dispositive power with respect to the shares held by the USVP X Funds. Casey Tansey is the sole managing partner of PMG X and may be deemed to have sole dispositive power over the reported securities held by the USVP X Funds and may be deemed to have shared voting power over the reported securities held by the USVP X Funds. Each of the foregoing persons disclaims beneficial ownership of such securities, except to the extent of any pecuniary interest therein. ( 5 )Represents common shares issued in the private placement which closed concurrently with the Merger. ( 6 )Each earn-out right represents a contingent right to receive one share of the Issuer's common stock. Pursuant to an "Earn-Out" provision in the Merger Agreement, the earn-out rights vest upon the Issuer's common stock achieving a price per share which equals or exceeds $20.00 over at least 20 trading days out of a 30 consecutive trading day period prior to August 26, 2023.

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