Sec Form 4 Filing - Kollender Richard S @ RAPID MICRO BIOSYSTEMS, INC. - 2021-09-09

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 Kollender Richard S 2. Issuer Name and Ticker or Trading Symbol RAPID MICRO BIOSYSTEMS, INC. [ [RPID]] 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 RAPID MICRO BIOSYSTEMS, INC., 1001 PAWTUCKET BOULEVARD WEST, SUITE 280 3. Date of Earliest Transaction (MM/DD/YY) 09/09/2021 (Street) LOWELL, MA01854 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 Class A Common Stock 09/09/2021 X 107,816 A $ 0.05 1,481,009 I Held by Quaker Bioventures II, L.P. ( 1 )

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 A1 Warrant (right to buy) $ 0.05 09/09/2021 X 82,010 ( 2 ) 07/24/2027 Class A Common Stock 82,010 $ 0 0 I Held by Quaker Bioventures II, L.P. ( 1 ) Series B1 Warrant (right to buy) $ 0.05 09/09/2021 X 12,903 ( 2 ) 12/06/2027 Class A Common Stock 12,903 $ 0 0 I Held by Quaker Bioventures II, L.P. ( 1 ) Series B1 Warrant (right to buy) $ 0.05 09/09/2021 X 12,903 ( 2 ) 01/17/2028 Class A Common Stock 12,903 $ 0 0 I Held by Quaker Bioventures II, L.P. ( 1 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Kollender Richard S C/O RAPID MICRO BIOSYSTEMS, INC. 1001 PAWTUCKET BOULEVARD WEST, SUITE 280 LOWELL, MA01854 X Signatures /s/ Jonathan Paris, Attorney-in-Fact for Richard S. Kollender 09/13/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )These shares are held directly by Quaker Bioventures II, L.P. The Reporting Person is an executive manager of Quaker Bioventures Capital II, LLC, the general partner of Quaker Bioventures Capital II, L.P, the general partner of Quaker Bioventures II, LP, and may be deemed to beneficially hold the shares but disclaims beneficial ownership thereof, except to the extent of any pecuniary interest therein. ( 2 )Immediately exercisable.

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).

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