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SEC EDGAR · Amended filing

MAGN: amended insider filing

An amended ownership report was filed. Read the original and amendment before comparing transactions.

Follow MAGN
Became public
Oct 19, 2026
Event / period date
May 29, 2025
Collected
Nov 8, 2026, 9:56 PM EST

Why this is connected

This filing identifies Magnera Corp as the issuer of the security. The company's SEC identifier connects it to MAGN.

Open the original source ↗Follow company activity in MAGN

Reported transactions

Brown Bruce (Director)

4,235 shares · Common Stock, Par Value $.01

May 29, 2025 · $11.8054 per share

Value calculated from the reported shares and prices: $49,995.87.

Code P covers open-market and private purchases. Grants, option exercises, and tax withholding are excluded from purchase results. Read the source footnotes for ownership and pricing details.

Source evidence

Read the source excerpt or record
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0609</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2025-05-29</periodOfReport>

    <dateOfOriginalSubmission>2025-05-30</dateOfOriginalSubmission>

    <issuer>
        <issuerCik>0000041719</issuerCik>
        <issuerName>Magnera Corp</issuerName>
        <issuerTradingSymbol>MAGN</issuerTradingSymbol>
        <issuerForeignTradingSymbol></issuerForeignTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001436840</rptOwnerCik>
            <rptOwnerName>Brown Bruce</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>false</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>9335 HARRIS CORNERS PKWY</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 300</rptOwnerStreet2>
            <rptOwnerCity>CHARLOTTE</rptOwnerCity>
            <rptOwnerState>NC</rptOwnerState>
            <rptOwnerZipCode>28269</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, Par Value $.01</value>
            </securityTitle>
            <transactionDate>
                <value>2025-05-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>4235</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>11.8054</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>16555</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Reports correction of shares purchased on May 29, 2025.</footnote>
        <footnote id="F2">Includes 4,523 shares of common stock held by the Bruce Brown Revocable Trust which were previously reported as indirectly owned.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Laura A. Jones, attorney-in-fact for Bruce Brown</signatureName>
        <signatureDate>2026-10-19</signatureDate>
    </ownerSignature>
</ownershipDocument>

Congressional trading in MAGN

These disclosures provide context. Their presence does not establish a link between a trader and the event.

Original documents control. Public records can be amended, and company connections may require interpretation. Nothing here is investment advice.