Sec Form 4 Filing - Flagship Ventures Fund V General Partner LLC @ Codiak BioSciences, Inc. - 2020-10-16

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 Flagship Ventures Fund V General Partner LLC 2. Issuer Name and Ticker or Trading Symbol Codiak BioSciences, Inc. [ CDAK] 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) 55 CAMBRIDGE PARKWAY, SUITE 800E 3. Date of Earliest Transaction (MM/DD/YY) 10/16/2020 (Street) CAMBRIDGE, MA02142 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 10/16/2020 C 543,686 A 543,686 I See Footnote ( 2 ) Common Stock 10/16/2020 C 543,686 A 543,686 I See Footnote ( 3 ) Common Stock 10/16/2020 C 338,630 A 882,316 I See Footnote ( 2 ) Common Stock 10/16/2020 C 338,630 A 882,316 I See Footnote ( 3 ) Common Stock 10/16/2020 C 95,861 A 978,177 I See Footnote ( 2 ) Common Stock 10/16/2020 C 95,861 A 978,177 I See Footnote ( 3 ) Common Stock 10/16/2020 P 165,000 A $ 15 1,143,177 I See Footnote ( 2 ) Common Stock 485,949 I See Footnote ( 6 )

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 ) 10/16/2020 C 4,250,000 ( 1 ) ( 1 ) Common Stock 543,686 ( 1 ) 0 I See Footnote ( 2 ) Series A Preferred Stock ( 1 ) 10/16/2020 C 4,250,000 ( 1 ) ( 1 ) Common Stock 543,686 ( 1 ) 0 I See Footnote ( 3 ) Series B Preferred Stock ( 4 ) 10/16/2020 C 2,416,666 ( 4 ) ( 4 ) Common Stock 338,630 ( 4 ) 0 I See Footnote ( 2 ) Series B Preferred Stock ( 4 ) 10/16/2020 C 2,416,666 ( 4 ) ( 4 ) Common Stock 338,630 ( 4 ) 0 I See Footnote ( 3 ) Series C Preferred Stock ( 5 ) 10/16/2020 C 660,048 ( 5 ) ( 5 ) Common Stock 95,861 ( 5 ) 0 I See Footnote ( 2 ) Series C Preferred Stock ( 5 ) 10/16/2020 C 660,048 ( 5 ) ( 5 ) Common Stock 95,861 ( 5 ) 0 I See Footnote ( 3 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Flagship Ventures Fund V General Partner LLC 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE, MA02142 X Flagship Ventures Fund V, L.P. 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE, MA02142 X Flagship V VentureLabs Rx Fund, L.P. 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE, MA02142 X AFEYAN NOUBAR 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE, MA02142 X Signatures Flagship Ventures Fund V General Partner LLC, By: /s/ Noubar B. Afeyan, Name: Noubar B. Afeyan, Ph.D., Title: Manager 10/20/2020 Signature of Reporting Person Date Flagship Ventures Fund V, L.P., By: Flagship Ventures Fund V General Partner LLC, its general partner, By: /s/ Noubar B. Afeyan, Name: Noubar B. Afeyan, Ph.D., Title: Manager 10/20/2020 Signature of Reporting Person Date Flagship V VentureLabs Rx Fund, L.P., By: Flagship Ventures Fund V General Partner LLC, its general partner, By: /s/ Noubar B. Afeyan, Name: Noubar B. Afeyan, Ph.D., Title: Manager 10/20/2020 Signature of Reporting Person Date /s/ Noubar B. Afeyan, Noubar B. Afeyan, Ph.D. 10/20/2020 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Each share of Series A Preferred Stock automatically converted into the Issuer's Common Stock on a 1-for-7.8170 basis upon the closing of the Issuer's initial public offering on October 16, 2020 and had no expiration date. ( 2 )Shares held by Flagship Ventures Fund V, L.P. ("Flagship Fund V"). Flagship Ventures Fund V General Partner LLC ("Flagship V GP") is the general partner of Flagship Fund V. Noubar B. Afeyan, Ph.D. serves as the sole manager of Flagship V GP. Each of the reporting persons except for Flagship Fund V disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein. ( 3 )Shares held by Flagship V VentureLabs Rx Fund, L.P. ("Flagship Fund V Rx"). Flagship V GP is the general partner of Flagship Fund V Rx. Noubar B. Afeyan, Ph.D. serves as the sole manager of Flagship V GP. Each of the reporting persons except for Flagship Fund V Rx disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein. ( 4 )Each share of Series B Preferred Stock automatically converted into the Issuer's Common Stock on a 1-for-7.1366 basis upon the closing of the Issuer's initial public offering on October 16, 2020 and had no expiration date. The reporting person previously reported shares of common stock into which the Series B Preferred Stock was convertible based on a 1-for-7.1295 conversion ratio estimated at pricing of the Issuer's initial public offering, which reflected a fixed conversion price plus an estimated adjustment based on the issuance of shares in the Issuer's initial public offering. ( 5 )Each share of Series C Preferred Stock automatically converted into the Issuer's Common Stock on a 1-for-6.8855 basis upon the closing of the Issuer's initial public offering on October 16, 2020 and had no expiration date. The reporting person previously reported shares of common stock into which the Series C Preferred Stock was convertible based on a 1-for-6.8758 conversion ratio estimated at pricing of the Issuer's initial public offering, which reflected a fixed conversion price plus an estimated adjustment based on the issuance of shares in the Issuer's initial public offering. ( 6 )Shares held by Flagship VentureLabs V LLC ("VentureLabs V"). Flagship Fund V is a member of VentureLabs V. Flagship VentureLabs V Manager LLC ("VentureLabs V Manager") is the manager of VentureLabs V. Flagship Pioneering, Inc. ("Flagship Pioneering") is the manager of VentureLabs V Manager. The general partner of Flagship Fund V is Flagship V GP. Noubar B. Afeyan, Ph.D. serves as the sole director of Flagship Pioneering and as the sole manager of Flagship V GP. Each of the reporting persons except for VentureLabs V disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interest therein.

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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