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<ownershipDocument>

    <schemaVersion>X0609</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2026-05-28</periodOfReport>

    <issuer>
        <issuerCik>0001649989</issuerCik>
        <issuerName>Outlook Therapeutics, Inc.</issuerName>
        <issuerTradingSymbol>OTLK</issuerTradingSymbol>
        <issuerForeignTradingSymbol></issuerForeignTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001717441</rptOwnerCik>
            <rptOwnerName>Sukhtian Ghiath M.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>true</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>7TH CIRCLE, ZAHRAN ST.</rptOwnerStreet1>
            <rptOwnerStreet2>ZAHRAN PLAZA BUILDING, 4TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>AMMAN</rptOwnerCity>
            <rptOwnerNonUSStateTerritory></rptOwnerNonUSStateTerritory>
            <rptOwnerCountry>M2</rptOwnerCountry>
            <rptOwnerZipCode>11844</rptOwnerZipCode>
            <rptOwnerStateDescription>JORDAN</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>true</isDirector>
            <isTenPercentOwner>true</isTenPercentOwner>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001804598</rptOwnerCik>
            <rptOwnerName>GMS Ventures &amp; Investments</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>true</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>C/O INTERTRUST CORP. SVCS. (CAYMAN) LTD.</rptOwnerStreet1>
            <rptOwnerStreet2>190 ELGIN AVENUE</rptOwnerStreet2>
            <rptOwnerCity>GEORGE TOWN</rptOwnerCity>
            <rptOwnerNonUSStateTerritory></rptOwnerNonUSStateTerritory>
            <rptOwnerCountry>E9</rptOwnerCountry>
            <rptOwnerZipCode>KY1-9007</rptOwnerZipCode>
            <rptOwnerStateDescription>CAYMAN ISLANDS</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>true</isDirector>
            <isTenPercentOwner>true</isTenPercentOwner>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>false</aff10b5One>

    <nonDerivativeTable>
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                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2026-05-28</value>
            </transactionDate>
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                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>8539709</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.5855</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
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                <sharesOwnedFollowingTransaction>
                    <value>22092068</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
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            <securityTitle>
                <value>Warrants (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>2.26</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2026-05-28</value>
            </transactionDate>
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                <transactionFormType>4</transactionFormType>
                <transactionCode>H</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F4"/>
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            <transactionAmounts>
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                    <value>3458571</value>
                </transactionShares>
                <transactionPricePerShare>
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                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2025-01-17</value>
            </exerciseDate>
            <expirationDate>
                <value>2030-01-17</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>3458571</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Warrants (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.5855</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2026-05-28</value>
            </transactionDate>
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                <transactionFormType>4</transactionFormType>
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            <transactionAmounts>
                <transactionShares>
                    <value>3458571</value>
                </transactionShares>
                <transactionPricePerShare>
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                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2025-01-17</value>
            </exerciseDate>
            <expirationDate>
                <value>2030-01-17</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>3458571</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
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                <sharesOwnedFollowingTransaction>
                    <value>3458571</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Warrants (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>2.26</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2026-05-28</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>H</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F5"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>3458571</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F5"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2025-03-11</value>
            </exerciseDate>
            <expirationDate>
                <value>2030-03-11</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>3458571</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Warrants (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.5855</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2026-05-28</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F5"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>3458571</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F5"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2025-03-11</value>
            </exerciseDate>
            <expirationDate>
                <value>2030-03-11</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>3458571</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3458571</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Warrants (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>1.4</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2026-05-28</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>H</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F6"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>8571428</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F6"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2025-05-27</value>
            </exerciseDate>
            <expirationDate>
                <value>2030-05-27</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>8571428</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Warrants (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.5855</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2026-05-28</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F6"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>8571428</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F6"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2025-05-27</value>
            </exerciseDate>
            <expirationDate>
                <value>2030-05-27</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>8571428</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
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                <sharesOwnedFollowingTransaction>
                    <value>8571428</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">On May 28, 2026, GMS Ventures and Investments (&quot;GMS Ventures&quot;) entered into a securities purchase agreement with Outlook Therapeutics, Inc. (the &quot;Issuer&quot;) pursuant to which the Issuer agreed to issue and sell 8,539,709 shares of the Issuer's common stock at $0.5855 per share in a registered direct offering for a total purchase price of approximately $5.0 million.</footnote>
        <footnote id="F2">These securities are held of record by GMS Ventures. Ghiath M. Sukhtian (&quot;Ghiath Sukhtian&quot;), a natural person, is the holder of a controlling interest in GMS Ventures. GMS Ventures has designated two representatives to serve on the Issuer's board of directors. Therefore, each of GMS Ventures and Ghiath Sukhtian may be deemed a director by deputization.</footnote>
        <footnote id="F3">By virtue of the relationships described above in Footnote 2, Ghiath Sukhtian may be deemed to have voting and investment power with respect to the securities held by GMS Ventures noted above and as a result may be deemed to beneficially own such securities for purposes of Rule 13d-3 under the Securities Exchange Act of 1934, as amended (the &quot;Exchange Act&quot;). The Reporting Persons disclaim beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Exchange Act, except to the extent of its or his pecuniary interest therein, if any. This report shall not be deemed an admission that any of the Reporting Persons are the beneficial owners of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.</footnote>
        <footnote id="F4">The transactions reported in Table II above involved the amendment of the outstanding Tranche A warrants issued on January 16, 2025 to reduce the exercise price from $2.26 per share to $0.5855 per share. The amendment is reported above as the cancellation of the old warrant and the acquisition of a new one.</footnote>
        <footnote id="F5">The transactions reported in Table II above involved the amendment of the outstanding Tranche B warrants issued on January 16, 2025 to reduce the exercise price from $2.26 per share to $0.5855 per share. The amendment is reported above as the cancellation of the old warrant and the acquisition of a new one.</footnote>
        <footnote id="F6">The transactions reported in Table II above involved the amendment of the outstanding warrants issued on May 27, 2025 to reduce the exercise price from $1.40 per share to $0.5855 per share. The amendment is reported above as the cancellation of the old warrant and the acquisition of a new one.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Ghiath M. Sukhtian, By: Lawrence Kenyon, Attorney-in-Fact</signatureName>
        <signatureDate>2026-06-01</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ GMS Ventures and Investments, By: Lawrence Kenyon, Attorney-in-Fact</signatureName>
        <signatureDate>2026-06-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
