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            <filer>
                <filerCredentials>
                    <cik>0001191229</cik>
                    <ccc>XXXXXXXX</ccc>
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            <liveTestFlag>LIVE</liveTestFlag>



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        <issuerInfo>
            <issuerCik>0001590877</issuerCik>
            <issuerName>REGENXBIO Inc.</issuerName>
            <secFileNumber>001-37553</secFileNumber>
            <issuerAddress>
                <ns2:street1>9804 Medical Center Drive </ns2:street1>
                <ns2:city>Rockville</ns2:city>
                <ns2:stateOrCountry>MD</ns2:stateOrCountry>
                <ns2:zipCode>20850</ns2:zipCode>
            </issuerAddress>
            <issuerContactPhone>2405528181</issuerContactPhone>
            <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>ARGERIS N KARABELAS</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
            <relationshipsToIssuer>
                <relationshipToIssuer>Director</relationshipToIssuer>
            </relationshipsToIssuer>
        </issuerInfo>
        <securitiesInformation>
            <securitiesClassTitle>COMMON</securitiesClassTitle>
            <brokerOrMarketmakerDetails>
                <name>Morgan Stanley Smith Barney LLC Executive Financial Services</name>
                <address>
                    <ns2:street1>1 New York Plaza</ns2:street1>
                    <ns2:street2>8th Floor</ns2:street2>
                    <ns2:city>New York</ns2:city>
                    <ns2:stateOrCountry>NY</ns2:stateOrCountry>
                    <ns2:zipCode>10004</ns2:zipCode>
                </address>
            </brokerOrMarketmakerDetails>
            <noOfUnitsSold>31000</noOfUnitsSold>
            <aggregateMarketValue>441750.00</aggregateMarketValue>
            <noOfUnitsOutstanding>49255966</noOfUnitsOutstanding>
            <approxSaleDate>08/01/2024</approxSaleDate>
            <securitiesExchangeName>NASDAQ</securitiesExchangeName>
        </securitiesInformation>
        <securitiesToBeSold>
            <securitiesClassTitle>Common</securitiesClassTitle>
            <acquiredDate>08/01/2024</acquiredDate>
            <natureOfAcquisitionTransaction>Exercise of Stock Options</natureOfAcquisitionTransaction>
            <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
            <isGiftTransaction>N</isGiftTransaction>
            <amountOfSecuritiesAcquired>31000</amountOfSecuritiesAcquired>
            <paymentDate>08/01/2024</paymentDate>
            <natureOfPayment>Cash</natureOfPayment>
        </securitiesToBeSold>
        <nothingToReportFlagOnSecuritiesSoldInPast3Months>N</nothingToReportFlagOnSecuritiesSoldInPast3Months>
        <securitiesSoldInPast3Months>
            <sellerDetails>
                <name>10b5-1 Sales for ARGERIS N KARABELAS</name>
                <address>
                    <ns2:street1>9804 Medical Center Drive </ns2:street1>
                    <ns2:city>Rockville</ns2:city>
                    <ns2:stateOrCountry>MD</ns2:stateOrCountry>
                    <ns2:zipCode>20850</ns2:zipCode>
                </address>
            </sellerDetails>
            <securitiesClassTitle>COMMON</securitiesClassTitle>
            <saleDate>07/29/2024</saleDate>
            <amountOfSecuritiesSold>11000</amountOfSecuritiesSold>
            <grossProceeds>165495.00</grossProceeds>
        </securitiesSoldInPast3Months>
        <securitiesSoldInPast3Months>
            <sellerDetails>
                <name>10b5-1 Sales for ARGERIS N KARABELAS</name>
                <address>
                    <ns2:street1>9804 Medical Center Drive </ns2:street1>
                    <ns2:city>Rockville</ns2:city>
                    <ns2:stateOrCountry>MD</ns2:stateOrCountry>
                    <ns2:zipCode>20850</ns2:zipCode>
                </address>
            </sellerDetails>
            <securitiesClassTitle>COMMON</securitiesClassTitle>
            <saleDate>07/01/2024</saleDate>
            <amountOfSecuritiesSold>10000</amountOfSecuritiesSold>
            <grossProceeds>112691.00</grossProceeds>
        </securitiesSoldInPast3Months>
        <remarks>The securities to be sold were and will be received upon the exercise of stock options over the next three months. The dates of acquisition and payment were and will be the dates of exercise/sale.&#13;
</remarks>
        <noticeSignature>
            <noticeDate>08/01/2024</noticeDate>
            <planAdoptionDates>
                <planAdoptionDate>03/25/2024</planAdoptionDate>
            </planAdoptionDates>
            <signature>/s/  Argeris N Karabelas</signature>
        </noticeSignature>
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144
0001191229
XXXXXXXX
LIVE
0001590877
REGENXBIO Inc.
001-37553
9804 Medical Center Drive
Rockville
MD
20850
2405528181
ARGERIS N KARABELAS
Director
COMMON
Morgan Stanley Smith Barney LLC Executive Financial Services
1 New York Plaza
8th Floor
New York
NY
10004
31000
441750.00
49255966
08/01/2024
NASDAQ
Common
08/01/2024
Exercise of Stock Options
Issuer
N
31000
08/01/2024
Cash
N
10b5-1 Sales for ARGERIS N KARABELAS
9804 Medical Center Drive
Rockville
MD
20850
COMMON
07/29/2024
11000
165495.00
10b5-1 Sales for ARGERIS N KARABELAS
9804 Medical Center Drive
Rockville
MD
20850
COMMON
07/01/2024
10000
112691.00
The securities to be sold were and will be received upon the exercise of stock options over the next three months. The dates of acquisition and payment were and will be the dates of exercise/sale.
08/01/2024
03/25/2024
/s/  Argeris N Karabelas