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Filed by a Party other than the Registrant  ☐

Check the appropriate box:
☐	​	​	Preliminary Proxy Statement
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☐	​	​	Definitive Proxy Statement
☒	​	​	Definitive Additional Materials
☐	​	​	Soliciting Material under §240.14a-12

Rapid Micro Biosystems, Inc.

(Name of Registrant as Specified in its Charter)

(Name of Person(s) Filing Proxy Statement, if Other Than the Registrant)

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