<SEC-DOCUMENT>0001104659-15-044326.txt : 20150609
<SEC-HEADER>0001104659-15-044326.hdr.sgml : 20150609
<ACCEPTANCE-DATETIME>20150609162817
ACCESSION NUMBER:		0001104659-15-044326
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20150605
FILED AS OF DATE:		20150609
DATE AS OF CHANGE:		20150609

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			SENIOR HOUSING PROPERTIES TRUST
		CENTRAL INDEX KEY:			0001075415
		STANDARD INDUSTRIAL CLASSIFICATION:	REAL ESTATE INVESTMENT TRUSTS [6798]
		IRS NUMBER:				043445278
		STATE OF INCORPORATION:			MD
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		TWO NEWTON PLACE
		STREET 2:		255 WASHINGTON STREET
		CITY:			NEWTON
		STATE:			MA
		ZIP:			02458
		BUSINESS PHONE:		6173323990

	MAIL ADDRESS:	
		STREET 1:		TWO NEWTON PLACE
		STREET 2:		255 WASHINGTON STREET
		CITY:			NEWTON
		STATE:			MA
		ZIP:			02458

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			PORTNOY BARRY M
		CENTRAL INDEX KEY:			0001241559

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-15319
		FILM NUMBER:		15921264

	MAIL ADDRESS:	
		STREET 1:		C/O REIT MANAGEMENT & RESEARCH LLC
		STREET 2:		TWO NEWTON PL., 255 WASH. ST., STE. 300
		CITY:			NEWTON
		STATE:			MA
		ZIP:			02458
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>a4.xml
<DESCRIPTION>4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2015-06-05</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001075415</issuerCik>
        <issuerName>SENIOR HOUSING PROPERTIES TRUST</issuerName>
        <issuerTradingSymbol>NYSE: SNH</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001241559</rptOwnerCik>
            <rptOwnerName>PORTNOY BARRY M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O REIT MANAGEMENT &amp; RESEARCH LLC</rptOwnerStreet1>
            <rptOwnerStreet2>TWO NEWTON PL., 255 WASH. ST., STE. 300</rptOwnerStreet2>
            <rptOwnerCity>NEWTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02458</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Shares of Beneficial Interest</value>
            </securityTitle>
            <transactionDate>
                <value>2015-06-05</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>8673.5</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>20.02</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>112760.45</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Shares of Beneficial Interest</value>
            </securityTitle>
            <transactionDate>
                <value>2015-06-05</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F4"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1289750</value>
                    <footnoteId id="F4"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>19.95</value>
                    <footnoteId id="F4"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1402510.45</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Shares of Beneficial Interest</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>286814.076</value>
                    <footnoteId id="F5"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">These Common Shares were issued as a portion of the management fee paid by the Issuer pursuant to the business management agreement between the Issuer and Reit Management &amp; Research LLC (&quot;RMR LLC&quot;) in effect as of the date of the transaction at $20.02, the average of the closing prices of the Common Shares on the New York Stock Exchange for each trading day during the month of May 2015.</footnote>
        <footnote id="F2">On May 19, 2015, RMR LLC distributed all of the Common Shares of the Issuer it then directly owned to Reit Management &amp; Research Trust (&quot;RMR Trust&quot;), then its sole member.  Mr. Portnoy is the Chairman, majority beneficial owner and a trustee of RMR Trust.</footnote>
        <footnote id="F3">Represents the pecuniary interest of Mr. Portnoy in Common Shares owned by RMR Trust.</footnote>
        <footnote id="F4">On June 5, 2015, RMR Trust, RMR LLC, Reit Management &amp; Research Inc. and the Issuer entered into a Transaction Agreement for an Up-C transaction pursuant to which, among other things, RMR Trust acquired 2,345,000 newly issued Common Shares valued at $19.95 per share, the volume weighted average trading price per Common Share on the New York Stock Exchange during the 20 business days prior to the closing of the transactions contemplated by the Transaction Agreement.</footnote>
        <footnote id="F5">Includes 5,414.343 shares acquired under the Senior Housing Properties Trust Dividend Reinvestment Plan since the last Section 16 filing by Mr. Portnoy.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Barry M. Portnoy</signatureName>
        <signatureDate>2015-06-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
