<SUBMISSION>
<ACCESSION-NUMBER>0001181431-08-070106
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20081229
<FILING-DATE>20081231
<DATE-OF-FILING-DATE-CHANGE>20081231
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>Foust Michael F
<CIK>0001307034
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-32336
<FILM-NUMBER>081278395
</FILING-VALUES>
<BUSINESS-ADDRESS>
<PHONE>(650) 233-3600
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>DIGITAL REALTY TRUST, INC.
<STREET2>2730 SAND HILL ROAD, SUITE 280
<CITY>MENLO PARK
<STATE>CA
<ZIP>94025
</MAIL-ADDRESS>
</REPORTING-OWNER>
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>Digital Realty Trust, Inc.
<CIK>0001297996
<ASSIGNED-SIC>6798
<IRS-NUMBER>000000000
<STATE-OF-INCORPORATION>MD
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>560 MISSION STREET
<STREET2>SUITE 2900
<CITY>SAN FRANCISCO
<STATE>CA
<ZIP>94105
<PHONE>(415)738-6500
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>560 MISSION STREET
<STREET2>SUITE 2900
<CITY>SAN FRANCISCO
<STATE>CA
<ZIP>94105
</MAIL-ADDRESS>
</ISSUER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>rrd228086.xml
<DESCRIPTION>FORM 4 FOR MICHAEL FOUST (CONVERT AND HOLD)
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-12-29</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001297996</issuerCik>
        <issuerName>Digital Realty Trust, Inc.</issuerName>
        <issuerTradingSymbol>DLR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001307034</rptOwnerCik>
            <rptOwnerName>Foust Michael F</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>560 MISSION STREET, SUITE 2900</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94105</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CEO and Director</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-12-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>25338</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>46111</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-12-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F3"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>4743</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F4"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>50854</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Class C Profits Interest Units</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F5"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2008-12-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>25338</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F6"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>25338</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Long-Term Incentive Units</value>
                <footnoteId id="F3"/>
                <footnoteId id="F4"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F5"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2008-12-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F3"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>4743</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F6"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>4743</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>59977</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Michael Foust converted 25,338 Class C Profits Interest Units into common limited partnership units (&quot;Common Units&quot;) of Digital Realty Trust, L.P., a Maryland Limited Partnership (the &quot;Operating Partnership&quot;), and subsequently redeemed the 25,338 Common Units for 25,338 shares of the common stock of Digital Realty Trust, Inc. (the &quot;Issuer&quot;), all in accordance with the requirements of the Limited Partnership Agreement of the Operating Partnership.</footnote>
        <footnote id="F2">Class C Units are membership interests in the Operating Partnership of which the Issuer is the general partner. Class C Units that have satisfied the performance condition and achieved full parity with Common Units receive the same quarterly distributions as Common Units, and may be converted into an equal number of Common Units on a one-for-one basis at any time. Common Units will be redeemable for cash based on the fair market value of an equivalent number of shares of the Issuer's common stock, or, at the election of the Issuer, for an equal number of shares of the Issuer's common stock. The Class C Units have achieved full parity with Common Units.</footnote>
        <footnote id="F3">Michael Foust converted 4,743 long-term incentive units into common limited partnership units (&quot;Common Units&quot;) of Digital Realty Trust, L.P., a Maryland Limited Partnership (the &quot;Operating Partnership&quot;), and subsequently redeemed the 4,743 Common Units for 4,743 shares of the common stock of Digital Realty Trust, Inc. (the &quot;Issuer&quot;), all in accordance with the requirements of the Limited Partnership Agreement of the Operating Partnership.</footnote>
        <footnote id="F4">Long-term incentive units are profits interest units in the Operating Partnership. Vested profits interest units may be converted into an equal number of Common Units in the Operating Partnership on a one-for-one basis at any time. Common Units are redeemable for cash based on the fair market value of an equivalent number of shares of the Issuer's common stock, or, at the election of the Issuer, for an equal number of shares of the Issuer's common stock, subject to adjustment in the event of stock splits, stock dividends, issuance of stock rights, specified extraordinary distributions or similar events.</footnote>
        <footnote id="F5">1 for 1.</footnote>
        <footnote id="F6">N/A</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Barbara Polster, attorney-in-fact</signatureName>
        <signatureDate>2008-12-31</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
