Sec Form 3/A Filing - Knopp Kevin J. @ 908 Devices Inc. - 2020-12-17

FORM 3/A 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 Knopp Kevin J. 2. Issuer Name and Ticker or Trading Symbol 908 Devices Inc. [ MASS] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) President and CEO (Last) (First) (Middle) C/O 908 DEVICES INC., 645 SUMMER STREET 3. Date of Earliest Transaction (MM/DD/YY) 12/17/2020 (Street) BOSTON, MA02210 4. If Amendment, Date Original Filed (MM/DD/YY) 12/17/2020 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, par value $0.001 ( 1 ) 758,667 D Common Stock, par value $0.001 ( 1 ) 505,777 I See Footnote ( 2 )

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 (option to buy) ( 3 ) $ 1.75 ( 4 ) 01/01/2027 Common Stock, par value $0.001 122,918 D Series A Preferred Stock ( 1 ) ( 5 ) ( 5 ) ( 5 ) Common Stock, par value $0.001 37,845 D Series A Preferred Stock ( 1 ) ( 5 ) ( 5 ) ( 5 ) Common Stock, par value $0.001 25,229 I See Footnote ( 2 ) Series B Preferred Stock ( 1 ) ( 5 ) ( 5 ) ( 5 ) Common Stock, par value $0.001 12,688 D Series B Preferred Stock ( 1 ) ( 5 ) ( 5 ) ( 5 ) Common Stock, par value $0.001 8,459 I See Footnote ( 2 ) Series D Preferred Stock ( 1 ) ( 5 ) ( 5 ) ( 5 ) Common Stock, par value $0.001 2,638 D Series D Preferred Stock ( 1 ) ( 5 ) ( 5 ) ( 5 ) Common Stock, par value $0.001 1,758 I See Footnote ( 2 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Knopp Kevin J. C/O 908 DEVICES INC. 645 SUMMER STREET BOSTON, MA02210 X President and CEO Signatures /s/ Michael S. Turner, as attorney-in-fact 04/30/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The original Form 3, filed December 17, 2020, is being amended by this Form 3 amendment to correct an administrative error related to the nature of the beneficial ownership of the shares held by the reporting person. Due to an administrative error, those shares were reported as being held directly by the reporting person, instead of held indirectly through the reporting person's trust, for which the reporting person may be deemed to be the beneficial owner. This Form 3 corrects such error by indicating that such shares are held indirectly instead of directly. ( 2 )The shares are owned directly by The Kevin J. Knopp Irrevocable Trust of 2018. The reporting person's brother-in-law is the trustee of The Kevin J. Knopp Irrevocable Trust of 2018 and has sole voting and dispositive control with respect to all securities held by such trust. The reporting person may be deemed to be the beneficial owner of the securities held by The Kevin J. Knopp Irrevocable Trust of 2018. ( 3 )The original Form 3, filed December 17, 2020, is being amended by this Form 3 amendment to correct the expiration date of these stock options. Due to an administrative error, the expiration date was listed as 6/22/2027 instead of 1/1/2027. ( 4 )The shares underlying the option become vested and exercisable in substantially equal monthly installments over the 48 months following January 1, 2017, subject to the reporting person's continued service through the applicable vesting date. ( 5 )Each share of Series A Preferred Stock, Series B Preferred Stock and Series D Preferred Stock (collectively, the "Preferred Shares") is convertible into shares of the Issuer's Common Stock at a 1:0.61459 ratio at any time at the holder's election, and automatically upon the closing of the Issuer's initial public offering ("IPO"), without payment of additional consideration. The Preferred Shares have no expiration date.

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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