<SEC-DOCUMENT>0001580808-21-000130.txt : 20210820
<SEC-HEADER>0001580808-21-000130.hdr.sgml : 20210820
<ACCEPTANCE-DATETIME>20210820194229
ACCESSION NUMBER:		0001580808-21-000130
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20210819
FILED AS OF DATE:		20210820
DATE AS OF CHANGE:		20210820

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Trivedi Dhrupad
		CENTRAL INDEX KEY:			0001570462

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-36343
		FILM NUMBER:		211194994

	MAIL ADDRESS:	
		STREET 1:		1 N. BRENTWOOD BLVD.
		STREET 2:		SUITE 1599
		CITY:			SAINT LOUIS
		STATE:			MO
		ZIP:			63105

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			A10 Networks, Inc.
		CENTRAL INDEX KEY:			0001580808
		STANDARD INDUSTRIAL CLASSIFICATION:	COMPUTER COMMUNICATIONS EQUIPMENT [3576]
		IRS NUMBER:				201446869
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		2300 ORCHARD PKWY
		CITY:			SAN JOSE
		STATE:			CA
		ZIP:			95131
		BUSINESS PHONE:		(408) 325-8668

	MAIL ADDRESS:	
		STREET 1:		2300 ORCHARD PKWY
		CITY:			SAN JOSE
		STATE:			CA
		ZIP:			95131
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_162950293026085.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2021-08-19</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001580808</issuerCik>
        <issuerName>A10 Networks, Inc.</issuerName>
        <issuerTradingSymbol>ATEN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001570462</rptOwnerCik>
            <rptOwnerName>Trivedi Dhrupad</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O A10 NETWORKS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>2300 ORCHARD PARKWAY</rptOwnerStreet2>
            <rptOwnerCity>SAN JOSE</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>95131</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Executive Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2021-08-19</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>39587</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>614586</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Performance-based Restricted Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2021-08-19</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>39587</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2025-02-02</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>39587.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>39588</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Performance-Based Restricted Stock Units were previously reported on February 4, 2021, each of which represents a contingent right to receive one share of common stock of ATEN, with vesting subject to the achievement of specified levels of the volume weighted average closing prices of a share of ATEN common stock during any one hundred (100) calendar day trading period between February 2, 2021 and February 2, 2025. The second milestone achievement date occurred on August 17, 2021, as certified by the compensation committee of ATEN on August 19, 2021, resulting in 39,587 units meeting the appropriate performance-based conditions. However, these shares remain subject to time-based vesting conditions and will therefore vest as to one-third (1/3) on August 30, 2021 and an additional one-third (1/3) on each of the first and second anniversaries of August 17, 2021, subject to continued employment. These shares are reflected on Table I.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Robert Cochran, as Attorney-in-Fact</signatureName>
        <signatureDate>2021-08-20</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
