<SEC-DOCUMENT>0001641172-25-001188.txt : 20250328
<SEC-HEADER>0001641172-25-001188.hdr.sgml : 20250328
<ACCEPTANCE-DATETIME>20250328161013
ACCESSION NUMBER:		0001641172-25-001188
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20250326
FILED AS OF DATE:		20250328
DATE AS OF CHANGE:		20250328

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			GARCIA RUBEN A
		CENTRAL INDEX KEY:			0002013617
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-41934
		FILM NUMBER:		25786077

	MAIL ADDRESS:	
		STREET 1:		C/O FIBROBIOLOGICS, INC.
		STREET 2:		455 E. MEDICAL CENTER BLVD., SUITE 300
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77598

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			FibroBiologics, Inc.
		CENTRAL INDEX KEY:			0001958777
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		ORGANIZATION NAME:           	03 Life Sciences
		EIN:				863329066
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		455 E. MEDICAL CENTER BLVD
		STREET 2:		SUITE 300
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77598
		BUSINESS PHONE:		281-671-5150

	MAIL ADDRESS:	
		STREET 1:		455 E. MEDICAL CENTER BLVD SUITE 300
		STREET 2:		SUITE 300
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77598

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	FibroBiologics Inc.
		DATE OF NAME CHANGE:	20221216
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>ownership.xml
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2025-03-26</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001958777</issuerCik>
        <issuerName>FibroBiologics, Inc.</issuerName>
        <issuerTradingSymbol>FBLG</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0002013617</rptOwnerCik>
            <rptOwnerName>GARCIA RUBEN A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O FIBROBIOLOGICS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>455 E. MEDICAL CENTER BLVD., SUITE 300</rptOwnerStreet2>
            <rptOwnerCity>HOUSTON,</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>77598</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>General Counsel</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>1.04</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2025-03-26</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>189000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2035-03-25</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>189000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>189000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">On March 26, 2025, the reporting person was granted an option to purchase 189,000 shares of common stock. One fourth (1/4th) of the option shares shall vest on the one-year anniversary of the grant date, and the remaining balance of the option shares shall vest in 36 equal consecutive monthly installments thereafter until fully vested so long as the reporting person remains in continuous service through such applicable vesting periods.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Ruben A. Garcia</signatureName>
        <signatureDate>2025-03-28</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
