<SEC-DOCUMENT>0001853904-26-000017.txt : 20260602
<SEC-HEADER>0001853904-26-000017.hdr.sgml : 20260602
<ACCEPTANCE-DATETIME>20260602194000
ACCESSION NUMBER:		0001853904-26-000017
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20260529
FILED AS OF DATE:		20260602
DATE AS OF CHANGE:		20260602

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Spignesi Robert G. Jr.
		CENTRAL INDEX KEY:			0001853904
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-40592
		FILM NUMBER:		261058442

	MAIL ADDRESS:	
		STREET 1:		C/O RAPID MICRO BIOSYSTEMS, INC.
		STREET 2:		1001 PAWTUCKET BOULEVARD WEST, SUITE 280
		CITY:			LOWELL
		STATE:			MA
		ZIP:			01854

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			RAPID MICRO BIOSYSTEMS, INC.
		CENTRAL INDEX KEY:			0001380106
		STANDARD INDUSTRIAL CLASSIFICATION:	LABORATORY ANALYTICAL INSTRUMENTS [3826]
		ORGANIZATION NAME:           	08 Industrial Applications and Services
		EIN:				208121647
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		25 HARTWELL AVENUE
		CITY:			LEXINGTON
		STATE:			MA
		ZIP:			02421
		BUSINESS PHONE:		978-349-3200

	MAIL ADDRESS:	
		STREET 1:		25 HARTWELL AVENUE
		CITY:			LEXINGTON
		STATE:			MA
		ZIP:			02421

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	RAPID MICRO BIOSYSTEMS INC
		DATE OF NAME CHANGE:	20061103
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wk-form4_1780443598.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0609</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2026-05-29</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001380106</issuerCik>
        <issuerName>RAPID MICRO BIOSYSTEMS, INC.</issuerName>
        <issuerTradingSymbol>RPID</issuerTradingSymbol>
        <issuerForeignTradingSymbol></issuerForeignTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001853904</rptOwnerCik>
            <rptOwnerName>Spignesi Robert G. Jr.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>false</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>C/O RAPID MICRO BIOSYSTEMS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>25 HARTWELL AVENUE</rptOwnerStreet2>
            <rptOwnerCity>LEXINGTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02421</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>PRESIDENT AND CEO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2026-05-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>12787</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1.955</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1190571</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Series A Warrant (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>1.955</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2026-05-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>12787</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2026-11-29</value>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2027-05-29</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>12787</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>12787</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Series B Warrant (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>2.34</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2026-05-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>12787</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2026-11-29</value>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2031-05-29</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>12787</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>12787</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">On May 29, 2026, the Reporting Person purchased, in a registered direct offering, 12,787 shares of the Issuer's Class A Common Stock, as well as an accompanying Series A Warrant to purchase 12,787 shares of the Issuer's Class A Common Stock (or pre-funded warrants in lieu thereof) and an accompanying Series B Warrant to purchase 12,787 shares of the Issuer's Class A Common Stock (or pre-funded warrants in lieu thereof). The purchase price of each share of Issuer Class A Common Stock and accompanying Series A and Series B Warrant was $1.955. The issuance of such securities was approved by the Issuer's compensation committee of the board of directors in accordance with Rule 16(b)-3 of the Securities Exchange Act of 1934, as amended.</footnote>
        <footnote id="F2">Includes 7,936 shares acquired under the Rapid Micro Biosystems, Inc. employee stock purchase plan on March 13, 2026.</footnote>
        <footnote id="F3">The Series A and Series B Warrants cannot be exercised for shares of the Issuer's Class A Common Stock if, as a result of such exercise, the holder, together with its affiliates and any other persons whose beneficial ownership would be aggregated for purposes of Section 13(d) of the Act, would beneficially own more than 9.99% of the total number of shares of the Issuer's Class A Common Stock then outstanding immediately following such exercise.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Sean M. Wirtjes, Attorney-in-Fact for Robert G. Spignesi, Jr.</signatureName>
        <signatureDate>2026-06-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
