SEC EDGAR · Insider purchase

MTUS: RICE RONALD A reported buying shares

1 reported purchase of non-derivative securities. Code P includes open-market and private purchases; it does not establish motive.

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Became public: Nov 5, 2026
Event / period date: Nov 5, 2026
Collected: Nov 8, 2026, 10:57 AM EST

Why this is connected

This filing identifies Metallus Inc. as the issuer of the security. The company's SEC identifier connects it to MTUS.

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Reported transactions

RICE RONALD A (Director)

10,000 shares · Common Shares

Nov 5, 2026 · $16.61 per share

Value calculated from the reported shares and prices: $166,100.00.

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</documentType>

    <periodOfReport>2026-11-05</periodOfReport>

    <issuer>
        <issuerCik>0001598428</issuerCik>
        <issuerName>Metallus Inc.</issuerName>
        <issuerTradingSymbol>MTUS</issuerTradingSymbol>
        <issuerForeignTradingSymbol></issuerForeignTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001224027</rptOwnerCik>
            <rptOwnerName>RICE RONALD A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>false</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>1835 DUEBER AVE. SW</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CANTON</rptOwnerCity>
            <rptOwnerState>OH</rptOwnerState>
            <rptOwnerZipCode>44706</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>true</isDirector>
            <isOfficer>false</isOfficer>
            <isTenPercentOwner>false</isTenPercentOwner>
            <isOther>false</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>false</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Shares</value>
            </securityTitle>
            <transactionDate>
                <value>2026-11-05</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>false</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>10000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>16.61</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>161818</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Price reported is the weighted average purchase price for shares purchased by the reporting owner on November 5, 2026. Shares were purchased at a variety of prices ranging from $16.12 to $16.85.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Kristine C. Syrvalin, as Attorney-in-Fact</signatureName>
        <signatureDate>2026-11-05</signatureDate>
    </ownerSignature>
</ownershipDocument>

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