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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
 MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen
 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 V35Ulyd9F2YzOmF+VPveZt740QxTdnq1Wscg820Hg7Cc8IxsHUZ9dnfZ7wSbOk9D
 C5wgnwEYgZrRCUOpquiQgQ==

<SEC-DOCUMENT>0001179110-10-015298.txt : 20101027
<SEC-HEADER>0001179110-10-015298.hdr.sgml : 20101027
<ACCEPTANCE-DATETIME>20101027175718
ACCESSION NUMBER:		0001179110-10-015298
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20100914
FILED AS OF DATE:		20101027
DATE AS OF CHANGE:		20101027

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Guggenheim Build America Bonds Managed Duration Trust
		CENTRAL INDEX KEY:			0001495825
		IRS NUMBER:				000000000
		STATE OF INCORPORATION:			DE

	BUSINESS ADDRESS:	
		STREET 1:		2455 CORPORATE WEST DRIVE
		CITY:			LISLE
		STATE:			IL
		ZIP:			60532
		BUSINESS PHONE:		630-505-3700

	MAIL ADDRESS:	
		STREET 1:		2455 CORPORATE WEST DRIVE
		CITY:			LISLE
		STATE:			IL
		ZIP:			60532

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			CLAYMORE SECURITIES INC
		CENTRAL INDEX KEY:			0001167303
		STATE OF INCORPORATION:			KS

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	811-22437
		FILM NUMBER:		101145806

	BUSINESS ADDRESS:	
		STREET 1:		CLAYMORE SECURITIES INC
		STREET 2:		2455 CORPORATE WEST DRIVE
		CITY:			LISLE
		STATE:			IL
		ZIP:			60532
		BUSINESS PHONE:		630-577-2201

	MAIL ADDRESS:	
		STREET 1:		2455 CORPORATE WEST DRIVE
		CITY:			LISLE
		STATE:			IL
		ZIP:			60532
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 3 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0203</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2010-09-14</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001495825</issuerCik>
        <issuerName>Guggenheim Build America Bonds Managed Duration Trust</issuerName>
        <issuerTradingSymbol>GBAB</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001167303</rptOwnerCik>
            <rptOwnerName>CLAYMORE SECURITIES INC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2455 CORPORATE WEST DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>LISLE</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60532</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>Investment Adviser Affiliate</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5240</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Guggenheim Funds Distributors, Inc. holds 5,240 shares in connection with the seeding of the Fund.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Kevin M. Robinson</signatureName>
        <signatureDate>2010-10-27</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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