DESCRIPTION OF DEBT SECURITIES

        References in this "Description of Debt Securities" section to "we," "us," "our" or "SNH" mean Senior Housing Properties Trust and not any of its consolidated subsidiaries, unless the context otherwise requires. The following is a summary of some general terms and provisions of debt securities that we may offer by this prospectus. Because it is a summary, it does not contain all of the information that may be important to you. If you want more information, you should read our Indenture dated February 18, 2016, as from time to time hereafter amended, supplemented or otherwise modified, or our 2016 Indenture, or the forms of indentures which are filed as exhibits to the registration statement of which this prospectus is a part. If we issue debt securities, we will file any additional final indentures, and any supplemental indentures or officer's certificates related to the particular series of debt securities issued, with the SEC, and you should read those documents for further information about the terms and provisions of such debt securities. See "Where You Can Find More Information." This summary is also subject to and qualified by reference to the descriptions of the particular terms of our debt securities to be described in the applicable prospectus supplement. The applicable prospectus supplement may add to, update or change the terms of such debt securities from those described below.

        The debt securities sold under this prospectus will be direct obligations of SNH and, unless otherwise stated in a prospectus supplement, will not be obligations of any of its subsidiaries. Such debt obligations may be secured or unsecured, and may be senior or subordinated indebtedness. Our debt securities will be issued under one or more indentures between us and a trustee, including, if applicable, our 2016 Indenture. Any indenture will be subject to and governed by the Trust Indenture

7

Table of Contents

Act of 1939, as amended, or the Trust Indenture Act. The statements made in this prospectus relating to our 2016 Indenture and any future indentures and the debt securities to be issued under the indentures are summaries of certain anticipated provisions of the indentures and are not complete.

General

        We may issue debt securities that rank "senior," "senior subordinated" or "junior subordinated," and which may be convertible into another security. The debt securities that we refer to as "senior" will be direct obligations of SNH and will rank equally and ratably in right of payment with our other indebtedness that is not subordinated, without giving effect to collateral arrangements. We may issue debt securities that will be subordinated in right of payment to the prior payment in full of our senior debt, as defined in the applicable prospectus supplement, and may rank equally and ratably with our other senior subordinated indebtedness, if any, without giving effect to collateral arrangements. We refer to these as "senior subordinated" securities. We may also issue debt securities that may be subordinated in right of payment to the senior subordinated securities. These would be "junior subordinated" securities. We have filed with the registration statement, of which this prospectus is a part, three separate forms of indenture, one for the senior securities (including our 2016 Indenture), one for the senior subordinated securities and one for the junior subordinated securities.

        We may issue debt securities without limit as to aggregate principal amount, in one or more series, in each case as we establish in one or more supplemental indentures. We need not issue all debt securities of one series at the same time. Unless we otherwise provide, we may reopen a series, without the consent of the holders of the series, for issuances of additional securities of that series.

        Our 2016 Indenture provides, and we anticipate that any indenture will provide, that we may, but need not, designate more than one trustee under an indenture, each with respect to one or more series of debt securities. Any trustee under any indenture may resign or be removed with respect to one or more series of debt securities, and we may appoint a successor trustee to act with respect to any such series.

        The applicable prospectus supplement will describe the specific terms relating to the series of debt securities we will offer, including, where applicable, the following:

•

the title and series designation and whether they are senior securities, senior subordinated securities or junior subordinated securities;



•

the aggregate principal amount of the debt securities offered and any limit on the aggregate principal amount of that series that may be authenticated and delivered;



•

the percentage of the principal amount at which we will issue the debt securities and, if other than the principal amount of the debt securities, the portion of the principal amount of the debt securities payable upon maturity of the debt securities;



•

if convertible, the initial conversion price, the conversion period and any other terms governing such conversion;



•

the stated maturity date;



•

any fixed or variable interest rate or rates per annum;



•

whether such interest will be payable in cash or additional debt securities of the same series or will accrue and increase the aggregate principal amount outstanding of such series;



•

the place where principal, premium, if any, and interest will be payable and where the debt securities can be surrendered for transfer, exchange or conversion;

8

Table of Contents

•

the date from which interest may accrue and any interest payment dates and any related record dates;



•

any sinking fund requirements;



•

any provisions for redemption or repurchase, including the redemption or repurchase price;



•

whether the debt securities are denominated or payable in U.S. dollars, a foreign currency or units of two or more currencies;



•

whether the amount of payments of principal of or premium, if any, or interest on the debt securities may be determined with reference to an index, formula or other method and the manner in which such amounts shall be determined;



•

the events of default and covenants of the debt securities, to the extent different from or in addition to those described in this prospectus;



•

whether we will issue the debt securities in certificated or book-entry form;



•

whether the debt securities will be in registered or bearer form and, if in registered form, the denominations, if other than $2,000 and integral multiples of $1,000 in excess thereof, or, if in bearer form, the denominations and terms and conditions relating thereto;



•

whether we will issue any of the debt securities in permanent global form and, if so, the terms and conditions, if any, upon which interests in the global security may be exchanged, in whole or in part, for the individual debt securities represented by the global security;



•

any addition or change to the provisions relating to the defeasance or covenant defeasance provisions of, or the satisfaction and discharge of, the debt securities;



•

whether we will pay additional amounts on the debt securities in respect of any tax, assessment or governmental charge and, if so, whether we will have the option to redeem the debt securities instead of making this payment;



•

the subordination provisions, if any, relating to the debt securities;



•

if the debt securities are to be issued upon the exercise of warrants, the time, manner and place for such debt securities to be authenticated and delivered;



•

any restriction or condition on the transferability of debt securities;



•

any addition or change to the provisions related to compensation and reimbursement of the trustee which applies to the debt securities;



•

any addition or change to the provisions related to supplemental indentures both with and without the consent of the holders;



•

provisions, if any, granting special rights to holders upon the occurrence of specified events;



•

any addition or change to the events of default which applies to any debt securities and any change in the right of the trustee or the requisite holders of such debt securities to declare the principal amount thereof due and payable pursuant to the indenture;



•

any addition or change to the covenants set forth in the indenture, or described in this prospectus or any prospectus supplement with respect to such series of debt securities; and



•

any other terms of debt securities of such series (which terms will not be inconsistent with the provisions of the Trust Indenture Act, but may modify, amend, supplement or delete any of the terms of the indenture, including those described in this prospectus or any prospectus supplement, with respect to such series).

9

Table of Contents

        We will describe in the applicable prospectus supplement any material U.S. federal income tax considerations applicable to the debt securities offered by such prospectus supplement.

        We may issue debt securities at less than the principal amount payable at maturity. We refer to these securities as "original issue discount" securities. If material or applicable, we will describe in the applicable prospectus supplement special U.S. federal income tax considerations applicable to original issue discount securities.

        Except as may be described in any prospectus supplement, our 2016 Indenture does not, and any future indenture will not, contain any other provisions that would limit our ability to incur indebtedness or that would afford holders of the debt securities protection in the event of a highly leveraged or similar transaction involving us or in the event of a change in control. You should review carefully the applicable prospectus supplement for information with respect to events of default and covenants applicable to the debt securities being offered.

Denominations, Interest, Registration and Transfer

        Unless otherwise described in the applicable prospectus supplement, we will issue debt securities of any series that are registered securities in minimum denominations of $2,000 and integral multiples of $1,000 in excess thereof, other than global securities, which may be of any denomination.

        Unless otherwise specified in the applicable prospectus supplement, we will pay the interest, principal and any premium at the corporate trust office of the trustee or, at our option, we may make payment of interest by check mailed to the address of the person entitled to the payment as it appears in the applicable register or by wire transfer of funds to that person at an account maintained within the United States or, in the case of global securities, in accordance with the procedures of the depositary for such securities.

        If we do not punctually pay or otherwise provide for interest on any interest payment date, the defaulted interest will be paid either:

•

to the person in whose name the debt security is registered at the close of business on a special record date the trustee will fix; or



•

in any other lawful manner, all as the applicable indenture describes.

        You may have your debt securities divided into more debt securities of smaller authorized denominations or combined into fewer debt securities of larger authorized denominations, as long as the total principal amount is not changed. We call this an "exchange."

        You may exchange or transfer debt securities at the office of the applicable trustee. The trustee acts as our agent for registering debt securities in the names of holders and transferring debt securities. We may change this appointment to another entity or perform this role ourselves. The entity performing the role of maintaining the list of registered holders is called the "registrar." The registrar will also perform transfers.

        You will not be required to pay a service charge to transfer or exchange debt securities, but you may be required to pay for any tax or other governmental charge associated with the exchange or transfer. The registrar will make the transfer or exchange only if it is satisfied with your proof of ownership.

Merger, Consolidation or Sale of Assets

        We may not consolidate with or merge into any other person or convey, transfer or lease all or substantially all of our properties and assets to any other person (other than one of our direct or

10

Table of Contents

indirect wholly owned subsidiaries), and we may not permit any other person (other than one of our direct or indirect wholly owned subsidiaries) to consolidate with or merge into us, unless:

•

we are the surviving entity or, in case we consolidate with or merge into another person, the person formed by such consolidation or merger is, or in case we convey, transfer or lease all or substantially all of our properties and assets to any person, such acquiring person is, an entity organized and validly existing under the laws of the United States, any state thereof or the District of Columbia and expressly assumes, by a supplemental indenture executed and delivered to the trustee, in form satisfactory to the trustee, the due and punctual payment of the principal of and any premium and interest on all applicable debt securities issued under the applicable indenture and the performance or observance of every covenant of the applicable indenture on our part to be performed or observed;



•

immediately after giving effect to such transaction, and treating any indebtedness which becomes an obligation of us or any of our subsidiaries as a result of such transaction as having been incurred by us or such subsidiary at the time of such transaction, no event of default, and no event which, after notice or lapse of time or both, would become an event of default, in each case under the applicable indenture, has happened and is continuing; and



•

we have delivered to the trustee an officer's certificate and an opinion of counsel, each stating that such consolidation, merger, conveyance, transfer or lease and, if a supplemental indenture is required in connection with such transaction, such supplemental indenture comply with the applicable indenture provisions described in this paragraph and that all conditions precedent provided for in the applicable indenture relating to such transaction have been complied with.

Events of Default and Related Matters

        Events of Default.     The term "event of default" for any series of debt securities means any of the following:

•

we do not pay the principal of or any premium on a debt security of that series when due;



•

we do not pay interest on a debt security of that series within 30 days after its due date;



•

we do not deposit any sinking fund payment for that series within 30 days after its due date;



•

we remain in breach of any other covenant of the applicable indenture (other than a covenant added to the indenture solely for the benefit of another series) for 60 days after we receive a notice of default specifying the breach and requiring that it be remedied. Only the trustee or holders of at least a majority in principal amount of outstanding debt securities of the affected series may send the notice;



•

we experience specified events of bankruptcy, insolvency or reorganization; or



•

any other event of default described in the applicable prospectus supplement occurs.

        Remedies if an Event of Default Occurs.     If an event of default has occurred and has not been cured, the trustee or the holders of not less than a majority in principal amount of the outstanding debt securities of the affected series may declare the entire principal amount of all the debt securities of that series to be due and payable immediately. If an event of default occurs because we experience specified events of bankruptcy, insolvency or reorganization, the principal amount of all the debt securities of that series will be automatically accelerated and become immediately due and payable, without any action by the trustee or any holder. At any time after the trustee or the holders have accelerated any series of debt securities, but before a judgment or decree for payment of the money due has been obtained, the holders of a majority in principal amount of the outstanding debt securities of the affected series may, under certain circumstances, rescind and annul such acceleration.

11

Table of Contents

        Except in cases of default where the trustee has some special duties, the trustee is not required to take any action under the applicable indenture at the request of any holders unless the holders offer the trustee reasonable protection from expenses and liability. We refer to this as an "indemnity." If reasonable indemnity is provided, the holders of not less than a majority in principal amount of the outstanding debt securities of the relevant series may direct the time, method and place of conducting any lawsuit or other formal legal action seeking any remedy available to the trustee. These majority holders may also direct the trustee in performing any other action under the applicable indenture, subject to certain limitations.

        Before you bypass the trustee and bring your own lawsuit or other formal legal action or take other steps to enforce your rights or protect your interests relating to the applicable indenture or debt securities issued under such indenture, the following must occur:

•

you must give the trustee written notice that an event of default has occurred and is continuing;



•

the holders of at least a majority in principal amount of all outstanding debt securities of the relevant series must make a written request that the trustee take action because of the default and must offer reasonable indemnity to the trustee against the cost and other liabilities of taking that action; and



•

the trustee must have not taken action for 60 days after receipt of the notice, request and offer of indemnity and must have not received from the holders of a majority in principal amount of all outstanding debt securities of the relevant series other conflicting directions within such 60 day period.

However, you are entitled at any time to bring a lawsuit for the payment of money due on your debt security after its due date.

        Every year we will furnish to the trustee a written statement by certain of our officers certifying that, to their best knowledge, we are in compliance with the applicable indenture and the debt securities, or else specifying any default.

Modification of an Indenture

        There are three types of changes we can make to the indentures and our debt securities:

        Changes Requiring Your Approval.     First, we cannot make certain changes to the indentures and our debt securities without the approval of each holder of debt securities affected by the change. The following is a list of those types of changes:

•

change the stated maturity of the principal of, or interest on, a debt security;



•

reduce the principal of, or the rate of interest on, a debt security;



•

reduce the amount of any premium due upon redemption;



•

reduce the amount of principal of an original issue discount security payable upon acceleration of its maturity;



•

change the currency or place of payment on a debt security;



•

impair a holder's right to sue for payment on or after the stated maturity of a debt security;



•

in the case of a subordinated debt security, modify the subordination provisions of such debt security in a manner that is adverse to the holders;



•

reduce the percentage of holders of debt securities whose consent is needed to modify or amend an indenture;

12

Table of Contents

•

reduce the percentage of holders of debt securities whose consent is needed to waive compliance with certain provisions of an indenture or certain defaults and their consequences;



•

waive past defaults in the payment of principal of or premium, if any, or interest on the debt securities or in respect of any covenant or provision that cannot be modified or amended without the approval of each holder of the debt securities; or



•

modify any of the foregoing provisions.

        Changes Requiring Majority Approval.     Second, certain changes require the approval of holders of not less than a majority in principal amount of the outstanding debt securities of the affected series. We require the same majority vote to obtain a waiver of a past default. However, we cannot obtain a waiver of a payment default or any other aspect of an indenture or the debt securities listed in the first category described above under "—Changes Requiring Your Approval" without the consent of each holder of debt securities affected by the waiver.

        Changes Not Requiring Approval.     Third, certain changes do not require any approval of holders of debt securities. These include:

•

to evidence the assumption by a successor obligor of our obligations;



•

to add to our covenants for the benefit of holders of debt securities of all or any series or to surrender any right or power conferred upon us;



•

to add any additional events of default for the benefit of holders of all or any series of debt securities;



•

to add to or change any provisions necessary to permit or facilitate the issuance of debt securities in bearer form, registrable or not registrable as to principal, and with or without interest coupons, or to permit or facilitate the issuance of debt securities in uncertificated form;



•

to add to, change or eliminate any of the provisions, so long as such addition, change or elimination does not apply to any debt security of any existing series of debt security entitled to the benefit of such provision or modify the rights of the holder of any such debt security with respect to such provision or such addition, change or elimination only becomes effective when there is no such security outstanding;



•

to add guarantees of or to secure all or any series of the debt securities;



•

to establish the forms or terms of debt securities of any series;



•

to evidence and provide for the acceptance of appointment of a successor trustee;



•

to cure any ambiguity, to correct or supplement any provision in the applicable indenture which may be defective or inconsistent with any other provision contained therein or to conform the terms of the indenture that are applicable to a series of debt securities to the description of the terms of such debt securities in the offering memorandum, prospectus supplement or other offering document applicable to such debt securities at the time of initial sale thereof;



•

to permit or facilitate the defeasance or satisfaction and discharge of debt securities of any series; provided that such action does not adversely affect the interests of any holder of debt securities in any material respect;



•

to prohibit the authentication and delivery of additional series of debt securities;



•

to add to or change or eliminate any provision as shall be necessary or desirable in accordance with any amendments to the Trust Indenture Act;



•

to comply with the rules of any applicable depositary; or

13

Table of Contents

•

to change anything that does not adversely affect the interests of the holders of debt securities of any series in any material respect.

        Further Details Concerning Approval.     Debt securities are not considered outstanding, and therefore the holders thereof are not eligible to vote or consent or give their approval or take other action under the applicable indenture, if we have deposited or set aside in trust for you money for their payment or redemption or if we or one of our affiliates own them. Debt securities are also not considered to be outstanding and therefore eligible to vote or consent or give their approval or take other action under the applicable indenture if they have been fully defeased or discharged, as described below under "—Discharge, Defeasance and Covenant Defeasance—Discharge" or "—Full Defeasance."

Discharge, Defeasance and Covenant Defeasance

        Discharge.     We may discharge our obligations to holders of any series of debt securities that have become due and payable or will become due and payable at their stated maturity within one year, or are to be called for redemption within one year, by depositing or causing to be deposited with the trustee, in trust, funds in the applicable currency in an amount sufficient to pay the debt securities of such series, including any premium and interest to the date of such deposit (in the case of debt securities which have become due and payable) or to such stated maturity or redemption date, as applicable.

        Full Defeasance.     We can, under particular circumstances, effect a full defeasance of any series of debt securities. By this we mean we can legally release ourselves from any payment or other obligations on the debt securities if, among other things, we put in place the arrangements described below to pay those debt securities and deliver certain certificates and opinions to the trustee:

•

we must irrevocably deposit (or cause to be deposited), in trust, for the benefit of all direct holders of the debt securities of such series money or government obligations (or, in some circumstances, depository receipts representing such government obligations), or a combination thereof, that will provide funds in an amount sufficient to pay the debt securities of such series, including any premium and interest on the debt securities of such series at their stated maturity or applicable redemption date (a "government obligation" for these purposes means, with respect to any series of debt securities, securities that are not callable or redeemable at the option of the issuer thereof and are (1) direct obligations of the government that issued the currency in which such series is denominated (or, if such series is denominated in euros, the direct obligations of any government that is a member of the European Monetary Union) for the payment of which its full faith and credit is pledged or (2) obligations of a person controlled or supervised by and acting as an agency or instrumentality of such government the payment of which is unconditionally guaranteed as a full faith and credit obligation by such government); and



•

we must deliver to the trustee a legal opinion stating that the current U.S. federal income tax law has changed or an Internal Revenue Service, or IRS, ruling has been issued, in each case to the effect that holders of the outstanding debt securities of such series will not recognize gain or loss for federal income tax purposes as a result of such full defeasance and will be subject to federal income tax on the same amounts and in the same manner and at the same times as would have been the case if such full defeasance had not occurred.

        Notwithstanding the foregoing, the following rights and obligations will survive full defeasance:

•

your right to receive payments from the trust when payments are due;



•

our obligations relating to registration and transfer of debt securities and lost or mutilated certificates; and

14

Table of Contents

•

our obligations to maintain a payment office and to hold moneys for payment in trust.

        Covenant Defeasance.     Under current U.S. federal income tax law, we can make the same type of deposit described above with respect to a series of debt securities and be released from the obligations imposed by most of the covenants with respect to such series and provisions of the applicable indenture with respect to such series, and we may omit to comply with those covenants and provisions without creating an event of default. This is called "covenant defeasance."

        If we accomplish covenant defeasance, the following provisions of an indenture and the debt securities of such series would no longer apply:

•

most of the covenants applicable to such series of debt securities and any events of default for failure to comply with those covenants;



•

any subordination provisions; and



•

certain other events of default as set forth in any prospectus supplement.

Conversion and Exchange Rights

        The terms and conditions, if any, upon which the debt securities are convertible into or exchangeable for common or preferred shares, other debt securities or other property will be set forth in the applicable prospectus supplement. Such terms will include whether the debt securities are convertible into or exchangeable for common or preferred shares, other debt securities or other property, the conversion or exchange price (or manner of calculation thereof), the conversion or exchange period, whether conversion or exchange will be at the option of the holders, the events requiring an adjustment of the conversion or exchange price, provisions affecting conversion or exchange in the event of the redemption of such debt securities and any restrictions on conversion or exchange, including restrictions directed at maintaining our qualification for taxation as a REIT under the Internal Revenue Code of 1986, as amended, or the Code.

Subordination

        We will describe in the applicable prospectus supplement the terms and conditions, if any, upon which any series of senior subordinated securities or junior subordinated securities is subordinated to debt securities of another series or to our other indebtedness. The terms will include a description of:

•

the indebtedness ranking senior to the debt securities being offered;



•

the restrictions, if any, on payments to the holders of the debt securities being offered while a default with respect to the senior indebtedness is continuing;



•

the restrictions, if any, on payments to the holders of the debt securities being offered following an event of default with respect to such debt securities; and



•

provisions requiring holders of the debt securities being offered to remit payments to holders of senior indebtedness.

Global Debt Securities

        We may issue the debt securities of a series in whole or in part in the form of one or more registered global securities that we will deposit with a depositary or with a nominee for a depositary identified in the applicable prospectus supplement and registered in the name of such depositary or nominee. In such case, we will issue one or more registered global securities denominated in an amount equal to the aggregate principal amount of all of the debt securities of the series to be issued and represented by such registered global security or securities.

15

Table of Contents

        Unless and until it is exchanged in whole or in part for debt securities in definitive registered form, a registered global security may not be transferred except as a whole:

•

by the depositary for such registered global security to its nominee;



•

by a nominee of the depositary to the depositary or another nominee of the depositary; or



•

by the depositary or its nominee to a successor of the depositary or a nominee of the successor.

        The prospectus supplement relating to a series of debt securities will describe the specific terms of the depositary arrangement with respect to any portion of such series represented by a registered global security. We currently anticipate that the following provisions will apply to all depositary arrangements for debt securities:

•

ownership of beneficial interests in a registered global security will be limited to persons that have accounts with the depositary for the registered global security, those persons being referred to as "participants," or persons that may hold interests through participants;



•

upon the issuance of a registered global security, the depositary for the registered global security will credit, on its book-entry registration and transfer system, the participants' accounts with the respective principal amounts of the debt securities represented by the registered global security beneficially owned by the participants;



•

any dealers, underwriters or agents participating in the distribution of the debt securities will designate the accounts to be credited; and



•

ownership of any beneficial interest in the registered global security will be shown on, and the transfer of any ownership interest will be effected only through, records maintained by the depositary for the registered global security (with respect to interests of participants) and on the records of participants (with respect to interests of persons holding through participants).

        The laws of some states may require that certain purchasers of securities take physical delivery of the securities in definitive form. These laws may limit the ability of those persons to own, transfer or pledge beneficial interests in registered global securities.

        So long as the depositary for a registered global security, or its nominee, is the registered owner of the registered global security, the depositary or the nominee, as the case may be, will be considered the sole owner or holder of the debt securities represented by the registered global security for all purposes under the applicable indenture. Except as set forth below, owners of beneficial interests in a registered global security:

•

will not be entitled to have the debt securities represented by a registered global security registered in their names;



•

will not receive or be entitled to receive physical delivery of the debt securities in the definitive form; and



•

will not be considered the owners or holders of the debt securities under the applicable indenture.

        Accordingly, each person owning a beneficial interest in a registered global security must rely on the procedures of the depositary for the registered global security and, if the person is not a participant, on the procedures of a participant through which the person owns its interest, to exercise any rights of a holder under the applicable indenture.

16

Table of Contents

        We understand that under currently existing industry practices, if we request any action of holders or if an owner of a beneficial interest in a registered global security desires to give or take any action that a holder is entitled to give or take under an indenture, the depositary for the registered global security would authorize the participants holding the relevant beneficial interests to give or take the action, and those participants would authorize beneficial owners owning through those participants to give or take the action or would otherwise act upon the instructions of beneficial owners holding through them.

        We will make payments of principal of and premium, if any, and interest, if any, on debt securities represented by a registered global security registered in the name of a depositary or its nominee to the depositary or its nominee, as the case may be, as the registered owners of the registered global security. Neither we nor any trustee or any other agent of us or a trustee will be responsible or liable for any aspect of the records relating to, or payments made on account of, beneficial ownership interests in the registered global security or for maintaining, supervising or reviewing any records relating to the beneficial ownership interests.

        We expect that the depositary for any debt securities represented by a registered global security, upon receipt of any payments of principal and premium, if any, and interest, if any, in respect of the registered global security, will immediately credit participants' accounts with payments in amounts proportionate to their respective beneficial interests in the registered global security as shown on the records of the depositary. We also expect that standing customer instructions and customary practices will govern payments by participants to owners of beneficial interests in the registered global security held through the participants, as is now the case with the securities held for the accounts of customers in bearer form or registered in "street name." We also expect that any of these payments will be the responsibility of the participants.

        No registered global security may be exchanged in whole or in part for debt securities registered, and no transfer of a registered global security in whole or in part may be registered, in the name of any person other than the depositary for such registered global security, unless (1) such depositary notifies us that it is unwilling or unable to continue as depositary for such registered global security or has ceased to be a clearing agency registered under the Securities Exchange Act of 1934, as amended, or the Exchange Act, and we fail to appoint an eligible successor depositary within 90 days, (2) an event of default shall have occurred and be continuing with respect to such debt securities, or (3) circumstances, if any, exist in addition to or in lieu of the foregoing as have been specified for that purpose in an applicable prospectus supplement. In any such case, the affected registered global security may be exchanged in whole or in part for debt securities in definitive form and the applicable trustee will register any such debt securities in such name or names as such depositary directs.

        We currently anticipate that certain registered global securities will be deposited with, or on behalf of, The Depository Trust Company, New York, New York, or DTC, and will be registered in the name of Cede & Co., as the nominee of DTC. DTC has advised us that DTC is a limited-purpose trust company organized under the New York Banking Law, a "banking organization" within the meaning of the New York Banking Law, a member of the Federal Reserve System, a "clearing corporation" within the meaning of the New York Uniform Commercial Code and a "clearing agency" registered pursuant to the provisions of Section 17A of the Exchange Act. DTC holds securities that its participants, or direct participants, deposit with DTC. DTC also facilitates the post-trade settlement among direct participants of sales and other securities transactions in deposited securities, through electronic computerized book-entry transfers and pledges between direct participants' accounts. This eliminates the need for physical movement of securities certificates. Direct participants include both U.S. and non-U.S. securities brokers and dealers, banks, trust companies, clearing corporations and certain other organizations. DTC is a wholly owned subsidiary of The Depository Trust & Clearing Corporation, or DTCC. DTCC is the holding company for DTC, National Securities Clearing Corporation and Fixed Income Clearing Corporation, all of which are registered clearing agencies. DTCC is owned by the

17

Table of Contents

users of its regulated subsidiaries. Access to the DTC system is also available to others such as both U.S. and non-U.S. securities brokers and dealers, banks, trust companies and clearing corporations that clear through or maintain a custodial relationship with a direct participant, either directly or indirectly. The rules applicable to DTC and its direct participants are on file with the SEC. The information in this paragraph concerning DTC and DTC's book-entry system has been obtained from sources that we believe to be reliable, but we take no responsibility for the accuracy thereof. In the event registered global securities are deposited with, or on behalf of, a depositary other than DTC, we will describe additional or differing terms of the depositary arrangements in the applicable prospectus supplement relating to that particular series of debt securities.

        We may also issue bearer debt securities of a series in the form of one or more global securities, referred to as "bearer global securities." We currently anticipate that we will deposit these bearer global securities with a common depositary for Euroclear Bank S.A./N.V. and Clearstream Banking, société anonyme, or with a nominee for the depositary identified in the prospectus supplement relating to that series. The prospectus supplement relating to a series of debt securities represented by a bearer global security will describe the specific terms and procedures, including the specific terms of the depositary arrangement and any specific procedures for the issuance of debt securities in definitive form in exchange for a bearer global security, with respect to the portion of the series represented by a bearer global security.

        Neither we nor any trustee assumes any responsibility for the performance by DTC or any other depositary or its participants of their respective obligations, including obligations that they have under the rules and procedures that govern their operations.

Governing Law

        Our 2016 Indenture and any future indentures and our debt securities issued thereunder are and will be governed by and construed in accordance with the laws of the State of New York.

DESCRIPTION OF SHARES OF BENEFICIAL INTEREST

        References in this "Description of Shares of Beneficial Interest" section to "we," "us" or "our" mean Senior Housing Properties Trust and not any of its consolidated subsidiaries, unless the context otherwise requires. The following description of the terms of our shares of beneficial interest is only a summary. For a complete description, please refer to our declaration of trust and bylaws, which have previously been filed with the SEC and are incorporated by reference into this prospectus, and this summary is qualified in its entirety thereby.

        Our declaration of trust authorizes us to issue up to an aggregate of 300,000,000 shares of beneficial interest, all of which are currently designated as common shares of beneficial interest, $.01 par value per share, or common shares. As of June 22, 2018, we had 237,643,781 common shares issued and outstanding. As of the date of this prospectus, no other class or series of shares of beneficial interest has been established and is outstanding.

        Our declaration of trust contains a provision permitting our Board of Trustees, without any action by our shareholders, to amend our declaration of trust to increase or decrease the total number of shares of beneficial interest or the number of shares of any class or series that we have authority to issue. Our declaration of trust further authorizes our Board of Trustees to reclassify any unissued shares from time to time by setting the preferences, conversion or other rights, voting powers, restrictions, limitations as to dividends or other distributions, qualifications or terms or conditions of redemption of our shares of beneficial interest or any new class or series of shares created by our Board of Trustees. We believe that giving these powers to our Board of Trustees will provide us with increased flexibility in structuring possible future financings and acquisitions and in meeting other business needs which might arise. Although our Board of Trustees has no intention at the present time

18

Table of Contents

of doing so, it could authorize us to issue a class or series of shares of beneficial interest that could, depending upon the terms of the class or series, delay or prevent a change in control.

Common Shares

        The following is a summary of some general terms and provisions of our common shares. Because it is a summary, it does not contain all of the information that may be important to you. If you want more information, you should read our declaration of trust and bylaws, copies of which have been filed with the SEC. See "Where You Can Find More Information." This summary is also subject to and qualified by reference to the description of the particular terms of common shares described in the applicable prospectus supplement.

        Except as otherwise described in the applicable prospectus supplement, and subject to the preferential rights of any other class or series of shares then outstanding or which may be issued, and to the ownership restrictions described below, all of our common shares are entitled:

•

to receive distributions on our common shares if, as and when authorized by our Board of Trustees and declared by us out of assets legally available for distribution; and



•

to share ratably in our assets legally available for distribution to our shareholders in the event of our liquidation, dissolution or winding up after payment of or adequate provision for all of our known debts and liabilities.

        Subject to the provisions of our declaration of trust regarding the restriction on the transfer of shares of beneficial interest, each outstanding common share entitles the holder to one vote on all matters submitted to a vote of shareholders, including the election of Trustees. Holders of our common shares do not have cumulative voting rights in the election of Trustees.

        Holders of our common shares have no preference, conversion, exchange, sinking fund, redemption or appraisal rights, or preemptive rights to subscribe for any of our securities.

        We will describe in the applicable prospectus supplement any material U.S. federal income tax considerations applicable to the common shares offered by such prospectus supplement.

        For additional information about our common shares, including the potential effects that provisions in our declaration of trust and bylaws may have in delaying or preventing a change in our control, see "Description of Certain Provisions of Maryland Law and of Our Declaration of Trust and Bylaws" below.

Preferred Shares

        The following is a summary of the general terms and provisions of the preferred shares that we may offer by this prospectus. We may issue preferred shares in one or more classes or series; each class or series of preferred shares will have its own rights and preferences. We will describe in a prospectus supplement (1) the specific terms of the class or series of any preferred shares offered through that prospectus supplement and (2) any general terms outlined in this section that will not apply to such preferred shares. Because this is a summary, it does not contain all of the information that may be important to you. If you want more information, you should read our declaration of trust, including any applicable articles supplementary, and bylaws, copies of which have been filed with the SEC. See "Where You Can Find More Information." This summary is also subject to and qualified by reference to the description of the particular terms of our securities described in the applicable prospectus supplement. The prospectus supplement may add to, update or change the terms of such securities from those described below.

19

Table of Contents

        General.     Our declaration of trust authorizes our Board of Trustees to determine the preferences, conversion or other rights, voting powers, restrictions, limitations as to dividends or other distributions, qualifications and terms and conditions of redemption of any preferred shares.

        The preferred shares will have the distribution, liquidation, redemption, voting and conversion rights described in this section unless we state otherwise in the applicable prospectus supplement. The liquidation preference is not indicative of the price at which the preferred shares will actually trade on or after the date of issuance. You should read the prospectus supplement relating to the particular class or series of the preferred shares for specific terms, including:

•

the distinctive designation of the applicable class or series of preferred shares and the number of shares that will constitute the class or series;



•

the initial offering price of such preferred shares;



•

relative ranking and preference of such preferred shares as to distribution rights and rights upon liquidation, dissolution or winding up of our affairs;



•

the distribution rate or rates (or method of calculation) on that class or series, the distribution periods, the date(s) on which distributions will be payable and whether the distributions will be cumulative, noncumulative or partially cumulative, and, if cumulative, the dates from which the distributions will start to cumulate;



•

any redemption or sinking fund provisions of that class or series;



•

any voting rights;



•

any conversion or exchange provisions;



•

any other specific terms, preferences, rights, limitations or restrictions of such preferred shares;



•

any limitations on issuance of any class or series of preferred shares ranking senior to or on a parity with such preferred shares as to distribution rights and rights upon liquidation, dissolution or winding up of our affairs;



•

any procedures for any auction and remarketing;



•

any listing of such preferred shares on any securities exchange; and



•

any limitations on record or beneficial ownership and restrictions on transfer, including those as may be appropriate to preserve our qualification for taxation as a REIT.

        Holders of our preferred shares have no preemptive rights to subscribe for any of our securities.

        We will describe in the applicable prospectus supplement any material U.S. federal income tax considerations applicable to the preferred shares offered by such prospectus supplement.

        The issuance of preferred shares, the issuance of rights to purchase preferred shares or the possibility of the issuance of preferred shares or such rights could have the effect of delaying or preventing a change in our control. In addition, the rights of holders of common shares will be subject to, and may be adversely affected by, the rights of holders of any preferred shares that we have issued or may issue in the future.

        For additional information about our preferred shares, including the potential effects that provisions in our declaration of trust and bylaws may have in delaying or preventing a change in our control, see "Description of Certain Provisions of Maryland Law and of Our Declaration of Trust and Bylaws" below.

        As described under "Description of Depositary Shares," we may, at our option, elect to offer depositary shares evidenced by depositary receipts. If we elect to do this, each depositary receipt will

20

Table of Contents

represent a fractional interest in a share of the particular class or series of the preferred shares issued and deposited with a depositary. The applicable prospectus supplement will specify that fractional interest.

        Rank.     Unless our Board of Trustees otherwise determines and we so specify in the applicable prospectus supplement, we expect that the preferred shares will, with respect to distribution rights and rights upon liquidation, dissolution or winding up of our affairs, rank senior to all our common shares.

        Distributions.     Holders of preferred shares of each class or series will be entitled to receive cash and/or share distributions at the rates and on the dates shown in the applicable prospectus supplement. We will pay each distribution to holders of record as they appear on our share transfer books on the record dates fixed by our Board of Trustees. In the case of preferred shares represented by depositary receipts, the records of the depositary referred to under "Description of Depositary Shares" will determine the persons to whom distributions are payable.

        We will not authorize or pay any distributions on a class or series of preferred shares or set aside funds for the payment of distributions if restricted or prohibited by law, or if the terms of any of our agreements, including agreements relating to our indebtedness or our other classes or series of preferred shares, prohibit that authorization, payment or setting aside of funds or provide that the authorization, payment or setting aside of funds is a breach of or a default under that agreement. We are now, and may in the future become, a party to agreements which restrict or prevent the payment of distributions on, or the purchase or redemption of, our shares of beneficial interest, including preferred shares. These restrictions may be indirect, such as covenants which require us to maintain specified levels of net worth or assets.

        Distributions on any class or series of preferred shares may be cumulative, noncumulative or partially cumulative, as specified in the applicable prospectus supplement. Cumulative distributions will be cumulative from and after the date shown in the applicable prospectus supplement. If our Board of Trustees fails to authorize a distribution that is noncumulative, the holders of the applicable class or series will have no right to receive, and we will have no obligation to pay, a distribution in respect of the applicable distribution period, whether or not distributions on that class or series are declared payable in the future.

        We refer to our common shares or other shares, now or hereafter issued, that rank junior to an applicable class or series of preferred shares with respect to distribution rights as junior shares. To the extent that the applicable class or series is entitled to a cumulative distribution, we may not declare or pay any distributions, or set aside any funds for the payment of distributions, on junior shares, or redeem or otherwise acquire junior shares, unless we also have declared and either paid or set aside for payment the full cumulative distributions on such class or series of preferred shares and on all our other class or series of preferred shares ranking senior to or on a parity with such class or series of preferred shares for all past distribution periods. The preceding sentence does not prohibit:

•

distributions payable in junior shares or options, warrants or rights to subscribe for or purchase junior shares;



•

conversions into or exchanges for junior shares;



•

pro rata offers to purchase or a concurrent redemption of all, or a pro rata portion of, the outstanding preferred shares of such class or series and any other class or series of shares ranking on a parity with such class or series of preferred shares with respect to distribution rights and rights upon our liquidation, dissolution or winding up; or



•

our redemption, purchase or other acquisition of shares under incentive, benefit or share purchase plans for Trustees, officers or employees, or others performing or providing similar services, for the purposes of enforcing restrictions upon ownership and transfer of our equity

21

Table of Contents

securities contained in our declaration of trust or bylaws or our redemption or other acquisition of rights issued under any shareholder rights plan we may adopt.

        To the extent an applicable class or series is noncumulative, we need only declare, and pay or set aside for payment, the distribution for the then current distribution period, before making distributions on or acquiring junior shares.

        Unless full cumulative distributions on a class or series of preferred shares have been or are contemporaneously declared and either paid or set aside for payment for all past distribution periods, no distributions (other than in junior shares) may be declared or paid or set aside for payment on any other class or series of preferred shares ranking on a parity with such class or series with respect to distribution rights. When distributions are not paid in full upon a class or series of preferred shares and any other class or series ranking on a parity with such class or series with respect to distribution rights, all distributions declared upon such class or series and any class or series ranking on a parity with such class or series with respect to distribution rights shall be allocated pro rata so that the amount of distributions declared per share on such class or series and such other shares shall in all cases bear to each other the same ratio that the accrued distributions per share on such class or series and such other shares bear to each other.

        Unless otherwise specified in the applicable prospectus supplement, we will credit any distribution payment made on an applicable class or series, including any capital gain distribution, first against the earliest accrued but unpaid distribution due with respect to the class or series.

        Redemption.     We may have the right or may be required to redeem one or more classes or series of preferred shares, as a whole or in part, in each case upon the terms, if any, and at the times and at the redemption prices shown in the applicable prospectus supplement.

        If a class or series of preferred shares is subject to mandatory redemption, we will specify in the applicable prospectus supplement the number of shares we are required to redeem, when those redemptions start, the redemption price and any other terms and conditions affecting the redemption. The redemption price will include all accrued and unpaid distributions, except in the case of noncumulative preferred shares. The redemption price may be payable in cash or other property, as specified in the applicable prospectus supplement. If the redemption price for preferred shares of any class or series is payable only from the net proceeds of our issuance of shares of beneficial interest, the terms of the preferred shares may provide that, if no shares of beneficial interest shall have been issued or to the extent the net proceeds from any issuance are insufficient to pay in full the aggregate redemption price then due, the preferred shares will automatically and mandatorily be converted into shares of beneficial interest pursuant to conversion provisions specified in the applicable prospectus supplement.

        Liquidation Preference.     The applicable prospectus supplement will specify the liquidation preference of the applicable class or series. Upon our voluntary or involuntary liquidation, dissolution or winding up of our affairs, before any distribution may be made to the holders of our common shares or any other shares of beneficial interest ranking junior in the distribution of assets upon any liquidation, dissolution or winding up of our affairs, to the applicable class or series, the holders of that class or series will be entitled to receive, out of our assets legally available for distribution to shareholders, liquidating distributions in the amount of the liquidation preference, plus an amount equal to all distributions accrued and unpaid. In the case of a noncumulative applicable class or series, accrued and unpaid distributions include only the then current distribution period. Unless otherwise specified in the applicable prospectus supplement, if liquidating distributions have been made in full to all holders of preferred shares, our remaining assets will be distributed among the holders of any other shares of beneficial interest ranking junior to the preferred shares upon liquidation, according to their rights and preferences and in each case according to their number of shares.

22

Table of Contents

        If, upon any voluntary or involuntary liquidation, dissolution or winding up of our affairs, our available assets are insufficient to pay the amount of the liquidating distributions on all outstanding shares of that class or series and the corresponding amounts payable on all equally ranking shares of beneficial interest upon any liquidation, dissolution or winding up of our affairs, then the holders of that class or series and all other equally ranking shares of beneficial interest shall share ratably in the distribution in proportion to the full liquidating distributions to which they would otherwise be entitled.

        Unless otherwise specified in the applicable prospectus supplement, after payment of the full amount of the liquidating distribution to which they are entitled, the holders of a class or series of preferred shares will have no right or claim to any of our remaining assets. Neither the sale, lease, transfer or conveyance of all or substantially all of our property or business, nor the merger or consolidation of us into or with any other entity or the merger or consolidation of any other entity into or with us or a statutory share exchange by us, shall be deemed to constitute the dissolution, liquidation or winding up of our affairs. In determining whether a distribution (other than upon voluntary or involuntary dissolution), by dividend, redemption or other acquisition of shares or otherwise, is permitted under Maryland law, amounts that would be needed, if we were to be dissolved at the time of the distribution, to satisfy the preferential rights upon dissolution of the holders of a class or series of preferred shares will not be added to our total liabilities.

        Voting Rights.     Holders of our preferred shares will not have any voting rights, except as described below or as otherwise from time to time specified in the applicable prospectus supplement.

        Unless otherwise specified in the applicable prospectus supplement, holders of our preferred shares (voting separately as a single class, together with all other class or series of preferred shares with similar voting rights) will be entitled to elect two additional Trustees to our Board of Trustees at our next annual meeting of shareholders and at each subsequent annual meeting if at any time distributions on the applicable class or series are in arrears for six consecutive quarterly periods. If the applicable class or series has a cumulative distribution, the right to elect additional Trustees described in the preceding sentence shall remain in effect until we declare and pay or set aside for payment all distributions accrued and unpaid on the applicable class or series. If the applicable class or series does not have a cumulative distribution, the right to elect additional Trustees described above shall remain in effect until we declare and pay or set aside for payment distributions accrued and unpaid on four consecutive quarterly periods on the applicable class or series. In the event the preferred shareholders are so entitled to elect Trustees, the entire Board of Trustees will be increased by two Trustees.

        Unless otherwise provided for in an applicable class or series, so long as any preferred shares are outstanding, we may not, without the affirmative vote or consent of a majority of the shares of each affected class or series of preferred shares outstanding at that time:

•

authorize, create or increase the authorized or issued amount of any class or series of shares of beneficial interest ranking senior to that class or series of preferred shares with respect to distribution and liquidation rights;



•

reclassify any authorized shares of beneficial interest into a class or series of shares of beneficial interest ranking senior to that class or series of preferred shares with respect to distribution and liquidation rights;



•

create, authorize or issue any security or obligation convertible into or evidencing the right to purchase any shares of beneficial interest ranking senior to that class or series of preferred shares with respect to distribution and liquidation rights; and



•

amend, alter or repeal the provisions of our declaration of trust or any articles supplementary relating to that class or series of preferred shares, whether by merger, consolidation or otherwise, in a manner that materially and adversely affects the class or series of preferred shares.

23

Table of Contents

The authorization, creation or increase of the authorized or issued amount of any class or series of shares of beneficial interest ranking on parity or junior to a class or series of preferred shares with respect to distribution and liquidation rights will not be deemed to materially and adversely affect that class or series. Further, with respect to any merger, consolidation or similar event, so long as a class or series of preferred shares remains outstanding with the terms thereof materially unchanged or the holders of shares of that class or series receive shares of the successor with substantially identical rights, taking into account that, upon the occurrence of such event, we may not be the surviving entity, the occurrence of such event will not be deemed to materially and adversely affect that class or series.

        The foregoing voting provisions will not apply if all of the outstanding shares of the class or series of preferred shares with the right to vote have been redeemed or called for redemption and sufficient funds have been deposited in trust for the redemption either at or prior to the act triggering these voting rights.

        As more fully described under "Description of Depositary Shares" below, if we elect to issue depositary shares, each representing a fraction of a share of a class or series, each depositary share will in effect be entitled to a fraction of a vote.

        Conversion and Exchange Rights.     We will describe in the applicable prospectus supplement the terms and conditions, if any, upon which you may, or we may require you to, convert or exchange shares of any class or series of preferred shares into common shares or any other class or series of shares of beneficial interest or debt securities or other property. The terms will include the number of common shares or other securities or property into which the preferred shares are convertible or exchangeable, the conversion or exchange price (or the manner of determining it), the conversion or exchange period, provisions as to whether conversion or exchange will be at the option of the holders of the class or series or at our option, the events requiring an adjustment of the conversion or exchange price and provisions affecting conversion or exchange upon the redemption of shares of the class or series.

DESCRIPTION OF DEPOSITARY SHARES

General

        References in this "Description of Depositary Shares" section to "we," "us" or "our" mean Senior Housing Properties Trust and not any of its consolidated subsidiaries, unless the context otherwise requires. The following is a summary of the general terms and provisions of the depositary shares that we may offer by this prospectus. Because it is a summary, it does not contain all of the information that may be important to you. If you want more information, you should read the form of deposit agreement and depositary receipts, which will be filed as exhibits to the registration statement of which this prospectus is a part prior to an offering of depositary shares. See "Where You Can Find More Information." This summary is also subject to and qualified by reference to the descriptions of the particular terms of our securities described in the applicable prospectus supplement. We will describe in a prospectus supplement (1) the specific terms of the depositary shares offered through that prospectus supplement and (2) any general terms outlined in this section that will not apply to such depositary shares. The applicable prospectus supplement also may add to, update or change the terms of such securities from those described below.

24

Table of Contents

        We may, at our option, elect to offer fractional interests in preferred shares, rather than whole preferred shares. If we exercise this option, we will appoint a depositary to issue depositary receipts representing those fractional interests. Preferred shares of each class or series represented by depositary shares will be deposited under a separate deposit agreement between us and the depositary. The prospectus supplement relating to a series of depositary shares will show the name and address of the depositary. Subject to the terms of the applicable deposit agreement, each owner of depositary shares will be entitled to all of the distribution, voting, conversion, redemption, liquidation and other rights and preferences of the preferred shares represented by those depositary shares.

        Depositary receipts issued pursuant to the applicable deposit agreement will evidence ownership of depositary shares. Upon surrender of depositary receipts at the office of the depositary, and upon payment of the charges provided in and subject to the terms of the deposit agreement, a holder of depositary shares will be entitled to receive the preferred shares underlying the surrendered depositary receipts.

        We will describe in the applicable prospectus supplement any material U.S. federal income tax considerations applicable to the depositary shares offered by such prospectus supplement.

Distributions

        The depositary will be required to distribute all cash distributions received in respect of the applicable preferred shares to the record holders of depositary receipts evidencing the related depositary shares, in proportion to the number of depositary receipts owned by such holders on the relevant record date, which will be the same date as the record date fixed by us for the distribution paid on the applicable preferred shares.

        If the distribution is other than in cash, a depositary will be required to distribute property received by it to the record holders of depositary receipts entitled thereto, unless the depositary determines that it is not feasible to make the distribution. In that case, the depositary may, with our approval, sell the property and distribute the net proceeds from the sale to the holders.

        Depositary shares that represent preferred shares converted or exchanged will not be entitled to distributions. The deposit agreement will also contain provisions relating to the manner in which any subscription or similar rights we offer to holders of the preferred shares will be made available to holders of depositary shares. All distributions will be subject to obligations of holders to file proofs, certificates and other information and to pay certain charges and expenses to the depositary.

Withdrawal of Preferred Shares

        You may receive the number of whole preferred shares and any money or other property represented by your depositary receipts after surrendering the depositary receipts at the corporate trust office of the depositary. Partial preferred shares will not be issued. If the depositary shares that you surrender exceed the number of depositary shares that represent the number of whole preferred shares you wish to withdraw, then the depositary will deliver to you at the same time a new depositary receipt evidencing the excess number of depositary shares. Once you have withdrawn your preferred shares, you will not be entitled to re-deposit those preferred shares under the deposit agreement in order to receive depositary shares. We do not expect that there will be any public trading market for withdrawn preferred shares.

Redemption of Depositary Shares

        If we redeem a class or series of the preferred shares underlying the depositary shares, the depositary will redeem those depositary shares from the proceeds received by it. The depositary will mail notice of redemption not less than 30 and not more than 60 days before the date fixed for

25

Table of Contents

redemption to the record holders of the depositary receipts evidencing the depositary shares being redeemed at their addresses appearing in the depositary's books. The redemption price per depositary share will be equal to the applicable fraction of the redemption price per share payable with respect to the class or series of the preferred shares. The redemption date for depositary shares will be the same as that of the preferred shares. If we are redeeming less than all of the depositary shares, the depositary will select the depositary shares we are redeeming by lot or pro rata as the depositary may determine.

        After the date fixed for redemption, the depositary shares called for redemption will no longer be deemed outstanding. All rights of the holders of the depositary shares and the related depositary receipts will cease at that time, except the right to receive the money or other property to which the holders of depositary shares were entitled upon redemption. Receipt of the money or other property is subject to surrender to the depositary of the depositary receipts evidencing the redeemed depositary shares.

Voting of the Preferred Shares

        Upon receipt of notice of any meeting at which the holders of the applicable preferred shares are entitled to vote, a depositary will be required to mail the information contained in the notice of meeting to the record holders of the applicable depositary receipts. Each record holder of depositary receipts on the record date, which will be the same date as the record date for voting preferred shares, will be entitled to instruct the depositary as to the exercise of the voting rights pertaining to the amount of preferred shares represented by the holder's depositary shares. If you do not instruct the depositary how to vote your shares, the depositary will abstain from voting those shares. The depositary will not be responsible for any failure to carry out an instruction to vote or for the effect of any such vote made so long as the action or inaction of the depositary is in good faith and is not the result of the depositary's gross negligence or willful misconduct.

Liquidation Preference

        Upon our liquidation, whether voluntary or involuntary, each holder of depositary shares will be entitled to the fraction of the liquidation preference accorded each preferred share represented by the depositary shares, as described in the applicable prospectus supplement.

Conversion or Exchange of Preferred Shares

        The depositary shares will not themselves be convertible into or exchangeable for common shares, preferred shares or any of our other securities or property. Nevertheless, if so specified in the applicable prospectus supplement, the depositary receipts may be surrendered by holders to the applicable depositary with written instructions to it to instruct us to cause conversion or exchange of the preferred shares represented by the depositary shares. Similarly, if so specified in the applicable prospectus supplement, we may require you to surrender all of your depositary receipts to the applicable depositary upon our requiring the conversion or exchange of the preferred shares represented by the depositary shares. We will agree that, upon receipt of the instruction and any amounts payable in connection with the conversion or exchange, we will cause the conversion or exchange using the same procedures as those provided for delivery of preferred shares to effect the conversion or exchange. If you are converting or exchanging only a part of the depositary shares, the depositary will issue you a new depositary receipt for any unconverted or unexchanged depositary shares.

26

Table of Contents

Amendment and Termination of a Deposit Agreement

        We and the applicable depositary are permitted to amend the provisions of the depositary receipts and the deposit agreement. However, the holders of a majority of the applicable depositary shares then outstanding must approve any amendment that adds or increases fees or charges or prejudices an important right of holders. Every holder of an outstanding depositary receipt at the time any amendment becomes effective, by continuing to hold the receipt, will be bound by the applicable deposit agreement, as amended.

        Any deposit agreement may be terminated by us upon not less than 30 days' prior written notice to the applicable depositary if (1) the termination is necessary to preserve our qualification for taxation as a REIT or (2) a majority of each class or series of preferred shares affected by the termination consents to the termination. When either event occurs, the depositary will be required to deliver or make available to each holder of depositary receipts, upon surrender of the depositary receipts held by the holder, the number of whole or fractional preferred shares as are represented by the depositary shares evidenced by the depositary receipts, together with any other property held by the depositary with respect to the depositary receipts. In addition, a deposit agreement will automatically terminate if:

•

all depositary shares have been redeemed;



•

there shall have been a final distribution in respect of the related preferred shares in connection with our liquidation and the distribution has been made to the holders of depositary receipts evidencing the depositary shares representing the preferred shares; or



•

each related preferred share shall have been converted or exchanged into securities not represented by depositary shares.

Charges of a Depositary

        We will pay all transfer and other taxes and governmental charges arising solely from the existence of a deposit agreement. In addition, we will pay the fees and expenses of a depositary in connection with the initial deposit of the preferred shares and any redemption of preferred shares. However, holders of depositary receipts will pay any transfer or other governmental charges and the fees and expenses of a depositary for any duties the holders request to be performed that are outside of those expressly provided for in the applicable deposit agreement.

Resignation and Removal of Depositary

        A depositary may resign at any time by delivering to us notice of its election to do so. In addition, we may at any time remove a depositary. Any resignation or removal will take effect when we appoint a successor depositary and it accepts the appointment. We must appoint a successor depositary within 60 days after delivery of the notice of resignation or removal. A depositary must be a bank or trust company having its principal office in the United States that has a combined capital and surplus of at least $50 million.

Miscellaneous

        The depositary will be required to forward to holders of depositary receipts any reports and communications from us that it receives with respect to the related preferred shares. Holders of depository receipts will be able to inspect the transfer books of the depository and the list of holders of depositary receipts upon reasonable notice.

        Neither we nor the depositary will be liable if the depositary is prevented from or delayed in performing its obligations under a deposit agreement by law or any circumstances beyond its control. Our obligations and those of the depositary under a deposit agreement will be limited to performing

27

Table of Contents

duties in good faith and without gross negligence or willful misconduct. Neither we nor the depositary will be obligated to prosecute or defend any legal proceeding in respect of any depositary receipts, depositary shares or related preferred shares unless satisfactory indemnity is furnished. We and the depositary will be permitted to rely on written advice of counsel or accountants, on information provided by persons presenting preferred shares for deposit, by holders of depositary receipts, or by other persons believed in good faith to be competent to give the information, and on documents believed in good faith to be genuine and signed by a proper party.

        If the depositary receives conflicting claims, requests or instructions from any holders of depositary receipts, on the one hand, and us, on the other hand, the depositary shall be entitled to act on the claims, requests or instructions received from us.

DESCRIPTION OF WARRANTS

        References in this "Description of Warrants" section to "we," "us" or "our" mean Senior Housing Properties Trust and not any of its consolidated subsidiaries, unless the context otherwise requires. The following is a summary of the general terms and provisions of the warrants that we may offer by this prospectus. Because it is a summary, it does not contain all of the information that may be important to you. If you want more information, you should read the forms of warrants and the warrant agreement which will be filed as exhibits to the registration statement of which this prospectus is a part. See "Where You Can Find More Information." This summary is also subject to and qualified by reference to the descriptions of the particular terms of our securities described in the applicable prospectus supplement. We will describe in a prospectus supplement (1) the specific terms of the warrants offered through that prospectus supplement and (2) any general terms outlined in this section that will not apply to such warrants. The applicable prospectus supplement also may add to, update or change the terms of such securities from those described below.

        We may issue, together with any other securities being offered or separately, warrants entitling the holder to purchase from or sell to us, or to receive from us the cash value of the right to purchase or sell, debt securities, preferred shares, depositary shares or common shares. We and a warrant agent will enter a warrant agreement pursuant to which the warrants will be issued. The warrant agent will act solely as our agent in connection with the warrants and will not assume any obligation or relationship of agency or trust for or with any holders or beneficial owners of warrants. We will file a copy of the forms of warrants and the warrant agreement with the SEC at or before the time of the offering of the applicable series of warrants.

        In the case of each series of warrants, the applicable prospectus supplement will describe the terms of the warrants being offered thereby. These include the following, if applicable:

•

the offering price;



•

the currencies in which such warrants are being offered;



•

the number of warrants offered;



•

the securities underlying the warrants;



•

the exercise price, the procedures for exercise of the warrants and the circumstances, if any, that will cause the warrants to be automatically exercised;



•

the date on which the warrants will expire;



•

the rights, if any, we have to redeem the warrants;



•

the name of the warrant agent; and



•

the other terms of the warrants.

28

Table of Contents

        We will describe in the applicable prospectus supplement any material U.S. federal income tax considerations applicable to the warrants offered by such prospectus supplement.

        Warrants may be exercised at the appropriate office of the warrant agent or any other office indicated in the applicable prospectus supplement. Before the exercise of warrants, holders will not have any of the rights of holders of the securities purchasable upon exercise and will not be entitled to payments made to holders of those securities.

        The warrant agreement may be amended or supplemented without the consent of the holders of the warrants to which the amendment or supplement applies to effect changes that are not inconsistent with the provisions of the warrants and that do not adversely affect the interests of the holders of the warrants. However, any amendment that materially and adversely alters the rights of the holders of warrants will not be effective unless the holders of a majority of the applicable warrants then outstanding approve the amendment. Every holder of an outstanding warrant at the time any amendment becomes effective, by continuing to hold the warrant, will be bound by the applicable warrant agreement as amended thereby. The prospectus supplement applicable to a particular series of warrants may provide that certain provisions of the warrants, including the securities for which they may be exercisable, the exercise price and the expiration date may not be altered without the consent of the holder of each warrant.

DESCRIPTION OF CERTAIN PROVISIONS OF MARYLAND LAW
AND OF OUR DECLARATION OF TRUST AND BYLAWS

        We are organized as a Maryland REIT. The following is a summary of our declaration of trust and bylaws and material provisions of Maryland law applicable to Maryland REITs, or the Maryland REIT Law. Because it is a summary, it does not contain all the information that may be important to you. If you want more information, you should read our declaration of trust and bylaws, copies of which are filed with the SEC or refer to the provisions of the Maryland REIT Law.

Restrictions on Transfer and Ownership of Shares

        Our declaration of trust provides that no person may own, or be deemed to own by virtue of the attribution provisions of the Code, more than 9.8% in value or in number of our outstanding shares or 9.8% in value or in number, whichever is more restrictive, of our outstanding common shares. Our declaration of trust also prohibits (1) any person from beneficially or constructively owning our shares if that ownership would result in us being "closely held" under Section 856(h) of the Code or otherwise cause us to fail to qualify for taxation as a REIT and (2) any person from transferring our shares if the transfer would result in our shares being owned by fewer than 100 persons.

        Our Board of Trustees, in its discretion, may exempt a person from the share ownership limitation if (1) it obtains such representations and undertakings from the person who makes a request therefor, as are reasonably necessary to ascertain that no individual's ownership of shares would result in our being "closely held" under Section 856(h) of the Code or otherwise failing to qualify for taxation as a REIT; (2) such person does not and represents that it will not own, actually or constructively, an interest in one of our tenants (or a tenant of any entity which we own or control) that would cause us to own, actually or constructively, more than a 9.9% interest in the tenant; and (3) such person agrees that any violation or attempted violation of such representations or undertakings (or other action which is contrary to the restrictions contained in our declaration of trust) will result in such shares being automatically transferred to a charitable trust in accordance with our declaration of trust. In connection with any requested exemption, our Board of Trustees may require such rulings from the IRS or opinions of counsel as it deems advisable in order to determine or ensure our qualification for taxation as a REIT and such representations, undertakings and agreements it deems advisable in order for it to make the foregoing determinations.

29

Table of Contents

        In determining whether to grant an exemption, our Board of Trustees may consider, among other factors, the following:

•

the general reputation and moral character of the person requesting an exemption;



•

whether the person's ownership of shares would be direct or through ownership attribution;



•

whether the person's ownership of shares would adversely affect our ability to acquire additional properties or engage in other business; and



•

whether granting an exemption would adversely affect any of our existing contractual arrangements.

        Any attempted transfer of our shares which, if effective, would result in our shares being owned by fewer than 100 persons shall be void ab initio, and the intended transferee shall acquire no rights in such shares.

        If a person attempts a transfer of our shares in violation of the ownership limitations described above, then the number of shares which would cause the violation shall (a) be automatically transferred to a charitable trust for the exclusive benefit of one or more charitable beneficiaries designated by us or (b) if such transfer is not effective to prevent the violation of the ownership limitations, be void ab initio. A transfer to the charitable trust will be deemed to be effective as of the close of business on the business day prior to the purported transfer or other event that results in the transfer to the charitable trust. The prohibited owner will not acquire any rights in these excess shares (except to the extent provided below upon sale of the shares), will not benefit economically from ownership of any excess shares, will have no rights to distributions and will not possess any rights to vote.

        Shares of beneficial interest held in the trust shall be issued and outstanding shares of beneficial interest. The trustee of the charitable trust shall have all voting rights and rights to distributions with respect to shares of beneficial interest held in the charitable trust, which rights shall be exercised for the exclusive benefit of the charitable beneficiary. Any dividend or other distribution paid prior to the discovery by us that shares of beneficial interest have been transferred to the trustee shall be paid by the recipient of such distribution to the trustee upon demand, and any distribution authorized but unpaid shall be paid when due to the trustee. Any dividend or other distribution so paid to the trustee shall be held in trust for the charitable beneficiary. The prohibited owner shall have no voting rights with respect to shares of beneficial interest held in the trust and, subject to Maryland law, the trustee of the charitable trust will have the authority to rescind as void any vote cast by the proposed transferee prior to our discovery that the shares have been transferred to the trust and to recast the vote in accordance with the desires of the trustee acting for the benefit of the charitable beneficiary. However, if we have already taken irreversible trust action, then the trustee will not have the authority to rescind and recast the vote.

        Within 20 days of receiving notice from us that our shares have been transferred to a charitable trust, the trustee will sell the shares held in the charitable trust to a person designated by the trustee whose ownership of the shares will not violate the ownership limitations set forth in our declaration of trust. Upon this sale, the interest of the charitable beneficiary in the shares sold will terminate and the trustee will distribute the net proceeds of the sale to the prohibited owner and to the charitable beneficiary as follows:

•

the prohibited owner will receive the lesser of:



(1)

the price paid by the prohibited owner for the shares or, if the prohibited owner did not give value for the shares in connection with the event causing the shares to be held in the charitable trust, for example, in the case of a gift, devise or other similar transaction, the market price (as defined in our declaration of trust) of the shares on the day of the event causing the shares to be transferred to the charitable trust; and

30

Table of Contents

(2)

the price per share received by the trustee from the sale or other disposition of the shares held in the charitable trust.



•

any net sale proceeds in excess of the amount payable to the prohibited owner shall be immediately paid to the charitable beneficiary.

        If, prior to our discovery that shares have been transferred to the charitable trust, a prohibited owner sells those shares, then:

•

those shares will be deemed to have been sold on behalf of the charitable trust; and



•

to the extent that the prohibited owner received an amount for those shares that exceeds the amount that the prohibited owner was entitled to receive from a sale by the trustee, the prohibited owner must pay the excess to the trustee upon demand.

        Also, shares held in the charitable trust will be offered for sale to us, or our designee, at a price per share equal to the lesser of:

•

the price per share in the transaction that resulted in the transfer to the charitable trust or, in the case of a devise or gift, the market price at the time of the devise or gift; and



•

the market price on the date we or our designee accepts the offer.

        We will have the right to accept the offer until the trustee has sold the shares held in the charitable trust. The net proceeds of the sale to us will be distributed to the prohibited owner.

        Any person who acquires or attempts or intends to acquire beneficial or constructive ownership of any shares that will or may violate the foregoing share ownership limitations, or any person who would have owned shares that resulted in a transfer to a charitable trust, is required to immediately give written notice to us of such event, or in the case of such a proposed or attempted transaction, give at least 15 days' prior written notice, and to provide to us such other information as we may request.

        Every owner of more than 5% of our shares is required to give written notice to us within 30 days after the end of each taxable year stating the name and address of the owner, the number of our shares which the owner beneficially owns and a description of the manner in which those shares are held. If the Code or applicable tax regulations specify a threshold below 5%, this notice provision will apply to those persons who own our shares of beneficial interest at the lower percentage. In addition, each shareholder is required to provide us upon demand with any additional information that we may request, in good faith, in order to determine our qualification for taxation as a REIT, to ensure compliance with the foregoing share ownership limitations and determine our compliance with the requirements of any taxing authority or other governmental authority.

        The restrictions in our declaration of trust described above will not preclude the settlement of any transaction entered into through the facilities of any national securities exchange or automated interdealer quotation system. Our declaration of trust provides, however, that the fact that the settlement of any transaction occurs will not negate the effect of any of the foregoing limitations and any transferee in this kind of transaction will be subject to all of the provisions and limitations described above.

        All certificates evidencing our shares and any share statements for our uncertificated shares may bear legends referring to the foregoing restrictions.

        The restrictions on transfer in our declaration of trust are intended to assist with REIT compliance under the Code and otherwise to promote our orderly governance. These restrictions do not apply to the Advisor (as defined in our declaration of trust) or its affiliates.

31

Table of Contents

Trustees

        Our declaration of trust and bylaws provide for a Board of Trustees of five members and that our Board of Trustees may change the number of Trustees, but there may be not less than three nor more than seven Trustees.

        Our Board of Trustees is divided into three classes. At each annual meeting, shareholders elect the successors of the class of Trustees whose term expires at that meeting for a term expiring at the annual meeting held in the third year following the year of their election. We believe that classification of our Board of Trustees helps to assure the continuity of our business strategies and policies. The classified board provision could have the effect of making the replacement of incumbent Trustees more time consuming and difficult. At least two annual meetings of shareholders will generally be required to effect a change in a majority of our Board of Trustees.

        There is no cumulative voting in the election of Trustees. Except as may be mandated by any applicable law or the listing requirements of the principal exchange on which our common shares are listed, and subject to the voting rights of any class or series of our shares of beneficial interest which may be hereafter created, (1) a plurality of all the votes cast at a meeting of our shareholders duly called and at which a quorum is present shall be sufficient to elect a Trustee in an uncontested election and (2) a majority of all the shares entitled to vote at a meeting of shareholders duly called and at which a quorum is present shall be sufficient to elect a Trustee in a contested election (which is an election at which the number of nominees exceeds the number of Trustees to be elected at such meeting). Under our Governance Guidelines, if an incumbent Trustee does not receive a majority of the votes cast in an uncontested election, the Trustee will submit an offer to resign from the Board of Trustees. In such circumstance, the Nominating and Governance Committee of our Board of Trustees will make a recommendation to the Board of Trustees on whether to accept or reject the resignation, or whether other action should be taken.

        In case of failure to elect Trustees at an annual meeting of shareholders, the incumbent Trustees will hold over and continue to direct the management of our business and affairs until they resign or their successors are elected and qualify. Any vacancy on our Board of Trustees may be filled only by a majority of the remaining Trustees, even if the remaining Trustees do not constitute a quorum, for the remaining term of the class in which the vacancy exists and until a successor is elected and qualifies. Our declaration of trust and bylaws provide that a Trustee may be removed only for cause, subject to conditions, by the affirmative vote of the holders of not less than two thirds of our common shares entitled to vote in the election of Trustees. This provision precludes shareholders from removing our incumbent Trustees unless they can obtain the requisite affirmative vote of shares. Under our bylaws, a Trustee may also be removed by the affirmative vote of all the remaining Trustees.

        Under our bylaws, a Trustee must be at least 21 years of age, not under legal disability, have substantial expertise or experience relevant to our business (as determined by our Board of Trustees), not have been convicted of a felony and meet the qualifications of an Independent Trustee or a Managing Trustee. An "Independent Trustee" is one who is not an employee of our Advisor (as defined in our declaration of trust), who is not involved in our day to day activities, who meets the qualifications of an independent trustee under our declaration of trust and who meets the qualifications of an independent director under the applicable rules of the principal securities exchange on which our common shares are listed for trading and the SEC, as those requirements may be amended from time to time. A "Managing Trustee" is one who has been an employee, officer or director of our Advisor or involved in our day to day activities for at least one year prior to his or her election. A majority of the Trustees holding office shall at all times be Independent Trustees, except for temporary periods due to vacancies. If the number of Trustees, at any time, is set at less than five, at least one Trustee will be a Managing Trustee. So long as the number of Trustees shall be five or greater, at least two Trustees will be Managing Trustees.

32

Table of Contents

Advance Notice of Trustee Nominations and New Business

        Annual Meetings of Shareholders.     Our bylaws provide that nominations of individuals for election to our Board of Trustees and proposals of other business to be considered at an annual meeting of shareholders may be made only (1) in our notice of the meeting, or otherwise properly brought before the meeting by or at the direction of our Board of Trustees, or (2) by a shareholder who is entitled to vote at the meeting, is entitled to make nominations or proposals and has complied with the advance notice procedures set forth in our bylaws.

        Under our bylaws, a shareholder's written notice of nominations of individuals for election to our Board of Trustees or other matters to be considered at an annual meeting of shareholders must be delivered to our Secretary at our principal executive offices not later than 5:00 p.m. (Eastern Time) on the 120th day nor earlier than the 150th day prior to the first anniversary of the date of our proxy statement for the preceding year's annual meeting; provided, however, that if the annual meeting is called for a date that is more than 30 days earlier or later than the first anniversary of the date of the preceding year's annual meeting, the notice must be delivered by not later than 5:00 p.m. (Eastern Time) on the 10th day following the earlier of the day on which (1) notice of the date of the annual meeting is mailed or otherwise made available or (2) public announcement of the date of the annual meeting is first made by us. Neither the postponement or adjournment of an annual meeting, nor the public announcement of such postponement or adjournment, commences a new time period for the giving of a shareholder's notice.

        Our bylaws set forth procedures for submission of nominations of individuals for election to our Board of Trustees and other proposals by our shareholders for consideration at an annual meeting of shareholders, including, among other things:

•

requiring that any one or more shareholders wishing to make a nomination or proposal of other business have continuously owned our shares of beneficial interest entitled to vote in the election of Trustees or propose other business for at least three years as of the date of the giving of the notice of the proposed nomination or proposal of other business, the record date for determining the shareholders entitled to vote at the meeting and the time of the annual meeting, with the aggregate shares owned by such shareholder(s) as of each such date during such three year period representing at least 1% of our shares of beneficial interest, that the shareholder(s) hold a certificate evidencing the aggregate number of shares of beneficial interest owned at the time of submitting a notice as of each such date, and that the shareholder(s) submit the proposal to our Secretary in accordance with the requirements of our bylaws;



•

providing that the advance notice provisions in our bylaws are the exclusive means for shareholders to make nominations or propose business for consideration at an annual meeting of our shareholders, except to the extent of matters which are required to be presented to our shareholders by applicable law, which have been properly presented in accordance with the requirements of such law;



•

requiring certain information and documentation be provided regarding any proposed nominee for election to our Board of Trustees by the proposing shareholder(s);



•

requiring certain information be provided with respect to any business other than the election of Trustees that the shareholder(s) propose(s) to bring before a meeting of our shareholders;



•

requiring certain information and documentation be provided as to the proposing shareholder(s) and certain of its (their) affiliates; and



•

providing that the proposing shareholder(s) is (are) responsible for ensuring compliance with the advance notice provisions, that any responses of the shareholder(s) to any request for information will not cure any defect in the notice of the proposing shareholder(s) and that

33

Table of Contents

neither we, our Board of Trustees, any committee of our Board of Trustees nor any of our officers has any duty to request clarification or updating information or to inform the proposing shareholder(s) of any defect in the notice of the proposing shareholder(s).

        Special Meetings of Shareholders.     With respect to special meetings of shareholders, our bylaws provide that only business brought before the meeting pursuant to our notice of the meeting or otherwise properly brought before the meeting by or at the direction of our Board of Trustees may be considered at such meeting. Nominations of individuals for election to our Board of Trustees may be made at a special meeting of shareholders at which Trustees are to be elected pursuant to our notice of meeting, by or at the direction of our Board of Trustees, or, provided that our Board of Trustees has determined that Trustees will be elected at such special meeting, by a shareholder who is a shareholder of record both at the time of giving of the notice provided for in our bylaws through and including the time of the special meeting, who is entitled to vote at the meeting and has complied with the advance notice procedures set forth in our bylaws. Under our bylaws, if we call a special meeting of shareholders for the purpose of electing one or more Trustees, any one or more shareholders may nominate an individual or individuals (as the case may be) for election to our Board of Trustees if the shareholder(s) satisfies the ownership, holding and certificate requirements required by our bylaws, as described above, for submitting nominations for consideration at an annual meeting of shareholders. To be timely, a shareholder's notice must be delivered not earlier than the 150th day prior to such special meeting and not later than 5:00 p.m. (Eastern Time) on the later of (1) the 120th day prior to such special meeting or (2) the 10th day following the day on which public announcement is first made of the date of the special meeting. Neither the postponement or adjournment of a special meeting, nor the public announcement of such postponement or adjournment, shall commence a new time period for the giving of a shareholder's notice.

Meetings of Shareholders; Voting by Shareholders

        Under our declaration of trust and bylaws, our annual meetings of shareholders will be held at a date and time set by our Board of Trustees. Meetings of our shareholders, including the annual meeting and any special meetings, may be called only by our Board of Trustees.

        Whenever shareholders are required or permitted to take any action by a vote, the action may only be taken by a vote at a shareholders meeting. Under our bylaws, shareholders do not have the right to take any action by written consent. With respect to matters brought before a meeting of shareholders other than the election of Trustees, except where a different voting standard is required by any applicable law, the listing requirements of the principal securities exchange on which our common shares are listed or a specific provision of our declaration of trust, 75% of all common shares entitled to vote at the meeting shall be required to approve the matter unless such matter has been previously approved by our Board of Trustees, in which case the vote required for approval is a majority of votes cast at the meeting.

        Under our declaration of trust, subject to the provisions of any class or series of our shares then outstanding, our shareholders are entitled to vote on the following matters: (1) the election of Trustees and the removal of Trustees; (2) any amendment to our declaration of trust; (3) termination of the Trust; (4) merger or consolidation of the Trust to the extent required by Title 8 of the Maryland General Corporation Law, or the MGCL, or the sale or disposition of substantially all our assets, in each case, to the extent a shareholder vote is required under the Maryland REIT Law, provided that such action has first been approved by our Board of Trustees; and (5) such other matters with respect to which our Board of Trustees has adopted a resolution declaring that a proposed action is advisable and directing that the matter be submitted to our shareholders for approval or ratification. Our shareholders will also be entitled to vote on such matters as may be required by our declaration of trust, bylaws or applicable law.

34

Table of Contents

Liability and Indemnification of Trustees and Officers

        The Maryland REIT Law permits a Maryland REIT to include in its declaration of trust a provision limiting the liability of its trustees and officers to the REIT and its shareholders for money damages except for liability resulting from (1) actual receipt of an improper benefit or profit in money, property or services or (2) active and deliberate dishonesty by the trustee or officer that was established by a final judgment as being material to the cause of action adjudicated. Our declaration of trust contains a provision which eliminates the liability of our Trustees and officers to the maximum extent permitted by the Maryland REIT Law.

        The Maryland REIT Law also permits a Maryland REIT to indemnify and advance expenses to its trustees, officers, employees and agents to the same extent permitted by the MGCL, for directors and officers of Maryland corporations. The MGCL permits a corporation to indemnify its present and former directors and officers, among others, against judgments, penalties, fines, settlements and reasonable expenses actually incurred by them in connection with any proceeding to which they may be made, or are threatened to be made, a party by reason of their service in those capacities. However, a Maryland corporation is not permitted to provide this type of indemnification if the following is established:

•

the act or omission of the director or officer was material to the matter giving rise to the proceeding and (1) was committed in bad faith or (2) was the result of active and deliberate dishonesty;



•

the director or officer actually received an improper personal benefit in money, property or services; or



•

in the case of any criminal proceeding, the director or officer had reasonable cause to believe that the act or omission was unlawful.

        Under Maryland law, a Maryland corporation may not indemnify a director or officer in a suit by the corporation or in its right in which the director or officer was adjudged liable to the corporation or in a suit in which the director or officer was adjudged liable on the basis that a personal benefit was improperly received. A court may order indemnification if it determines that the director or officer is fairly and reasonably entitled to indemnification, even though the director or officer did not meet the prescribed standard of conduct or was adjudged liable on the basis that personal benefit was improperly received. However, indemnification for an adverse judgment in a suit by the corporation or in its right, or for a judgment of liability on the basis that a personal benefit was improperly received, is limited to expenses. The MGCL permits a corporation to advance reasonable expenses to a director or officer upon the corporation's receipt of the following:

•

a written affirmation by the director or officer of his or her good faith belief that he or she has met the standard of conduct necessary for indemnification by the corporation; and



•

a written undertaking by him or her, or on his or her behalf, to repay the amount paid or reimbursed by the corporation if it is ultimately determined that this standard of conduct was not met.

        Our declaration of trust requires us, to the maximum extent permitted by Maryland law, in effect from time to time, to indemnify (1) any present or former Trustee or officer of us or (2) any individual who, while a Trustee of us and at our request, serves or has served as a trustee, director, officer, partner, employee or agent of another REIT, corporation, partnership, joint venture, trust, employee benefit plan or other enterprise and who is made or threatened to be made a party to a proceeding by reason of his or her service in that capacity and to pay or reimburse their reasonable expenses in advance of final disposition of the proceeding. Our declaration of trust also permits us to indemnify and advance expenses to any person who served any predecessor of ours in the capacities described

35

Table of Contents

above and any present or former shareholder, employee or agent of us or any such predecessor. Our declaration of trust also obligates us to pay or reimburse the people described above for reasonable expenses in advance of final disposition of a proceeding.

        We have also entered into indemnification agreements with our Trustees and officers providing for procedures for indemnification by us to the maximum extent permitted by Maryland law and advancements by us of certain expenses and costs relating to claims, suits or proceedings arising from their service to us.

        The SEC has expressed the opinion that indemnification of trustees, officers or persons otherwise controlling a company for liabilities arising under the Securities Act is against public policy and is therefore unenforceable.

Shareholder Liability

        Under the Maryland REIT Law, a shareholder is generally not personally liable for the obligations of a REIT formed under Maryland law solely as a result of his or her status as a shareholder. Our declaration of trust provides that no shareholder will be liable for any debt, claim, demand, judgment or obligation of any kind by reason of being a shareholder. While we intend to conduct our business in a manner designed to minimize potential shareholder liability, we can give no assurance that you can avoid liability in all instances in all jurisdictions. We have not provided in the past and do not intend to provide insurance covering these risks to our shareholders.

        Our declaration of trust and bylaws provide that, to the fullest extent permitted by law, any shareholder who violates the declaration of trust or bylaws will indemnify us and hold us harmless from and against all costs, expenses, penalties, fines and other amounts, including attorneys' and other professional fees, arising from the shareholder's violation, together with interest on such amounts. Our bylaws further provide that matters for which a shareholder is liable and obligated to indemnify and hold us harmless include any breach or failure to fully comply with any covenant, condition or provision of our declaration of trust or bylaws, including the advance notice provisions pertaining to shareholder nominations and other proposals, and these provisions of our declaration of trust and bylaws apply to derivative actions brought against us in which the shareholder is not the prevailing party.

Disputes by Shareholders

        Our bylaws provide that actions brought against us or any Trustee, officer, manager (including RMR LLC or its successor), agent or employee of ours, by a shareholder, including derivative and class actions, shall, on the demand of any party to such dispute, be resolved through binding arbitration in accordance with the procedures set forth in our bylaws.

Forum for Certain Disputes

        Our bylaws provide that the Circuit Court for Baltimore City, Maryland will be the sole and exclusive forum for (1) any derivative action or proceeding brought on our behalf, (2) any action asserting a claim of breach of a duty owed by any of our Trustees, officers, managers, agents or employees to us or our shareholders, (3) any action asserting a claim against us or any of our Trustees, officers, managers, agents or employees arising pursuant to Maryland law or our declaration of trust or bylaws, including any disputes, claims or controversies brought by or on behalf of any of our shareholders or (4) any action asserting a claim against us or any of our Trustees, officers, managers, agents or employees governed by the internal affairs doctrine of the State of Maryland. Any person or entity purchasing or otherwise acquiring any interest in our shares of beneficial interest is deemed to have notice of and consented to this provision. This choice of forum provision will limit a shareholder's ability to bring a claim in another judicial forum, including in a judicial forum that the shareholder believes is favorable for disputes with us or our Trustees, officers, managers, agents or employees,

36

Table of Contents

which may discourage lawsuits against us and our Trustees, officers, managers, agents or employees. This provision of our bylaws does not abrogate or supersede other provisions of our contracts which may require the resolution of such disputes by arbitration.

Transactions with Affiliates

        Our declaration of trust allows us to enter into contracts and transactions of any kind with any person, including any of our Trustees, officers, employees or agents or any person affiliated with them. Other than general legal principles applicable to self dealing by Trustees and interested Trustee transactions, there are no prohibitions in our declaration of trust or bylaws which would prohibit dealings between us and our affiliates.

Regulatory Compliance and Disclosure

        Our bylaws provide that any shareholder who, by virtue of such shareholder's ownership of our shares of beneficial interest or actions taken by the shareholder affecting us, triggers the application of any requirement or regulation of any federal, state, municipal or other governmental or regulatory body on us or any of our subsidiaries shall promptly take all actions necessary and fully cooperate with us to ensure that such requirements or regulations are satisfied without restricting, imposing additional obligations on or in any way limiting the business, assets, operations or prospects of us or any of our subsidiaries. If the shareholder fails or is otherwise unable to promptly take such actions so as to cause satisfaction of such requirements or regulations, such shareholder shall promptly divest a sufficient number of our shares necessary to cause the application of such requirement or regulation to not apply to us or any of our subsidiaries. If the shareholder fails to cause such satisfaction or divest itself of such sufficient number of our shares by not later than the 10th day after triggering such requirement or regulation referred to in the bylaws, then any of our shares beneficially owned by such shareholder at and in excess of the level triggering the application of such requirement or regulation shall, to the fullest extent permitted by law, be deemed to constitute shares held in violation of the ownership limitations set forth in our declaration of trust. Also, our bylaws provide that if the shareholder who triggers the application of any regulation or requirement fails to satisfy the requirements or regulations or to take curative actions within such 10 day period, we may take all other actions which our Board of Trustees deems appropriate to require compliance or to preserve the value of our assets, and we may charge the offending shareholder for our costs and expenses as well as any damages which may result.

        Our bylaws also provide that if a shareholder, by virtue of such shareholder's ownership of our shares of beneficial interest or its receipt or exercise of proxies to vote shares owned by other shareholders, would not be permitted to vote such shareholder's shares or proxies for such shares in excess of a certain amount pursuant to applicable law but our Board of Trustees determines that the excess shares or shares represented by the excess proxies are necessary to obtain a quorum, then such shareholder shall not be entitled to vote any such excess shares or proxies, and instead such excess shares or proxies may, to the fullest extent permitted by law, be voted by the Advisor (as defined in our declaration of trust) or another person designated by our Board of Trustees, in proportion to the total shares otherwise voted on such matter.

Business Combinations

        The MGCL contains a provision which regulates business combinations with interested shareholders. This provision applies to REITs formed under Maryland law like us. Under the MGCL, business combinations such as mergers, consolidations, share exchanges, or, in circumstances specified in the statute, an asset transfer or issuance or reclassification of equity securities between a REIT formed under Maryland law and an interested shareholder or an affiliate of an interested shareholder are prohibited for five years after the most recent date on which the interested shareholder becomes an

37

Table of Contents

interested shareholder. Under the MGCL the following persons are deemed to be interested shareholders:

•

any person who beneficially owns, directly or indirectly, 10% or more of the voting power of the trust's outstanding voting shares; or



•

an affiliate or associate of the trust who, at any time within the two year period immediately prior to the date in question, was the beneficial owner, directly or indirectly, of 10% or more of the voting power of the then outstanding voting shares of the trust.

        After the five year prohibition period has ended, a business combination between a trust and an interested shareholder generally must be recommended by the board of trustees of the trust and must receive the following shareholder approvals:

•

the affirmative vote of at least 80% of the votes entitled to be cast by holders of outstanding voting shares of the trust; and



•

the affirmative vote of at least two thirds of the votes entitled to be cast by holders of voting shares other than shares held by the interested shareholder with whom or with whose affiliate or associate the business combination is to be effected or held by an affiliate or associate of the interested shareholder.

        The shareholder approvals discussed above are not required if the trust's shareholders receive the minimum price set forth in the MGCL for their shares and the consideration is received in cash or in the same form as previously paid by the interested shareholder for its shares.

        The foregoing provisions of the MGCL do not apply, however, to business combinations that are approved or exempted by our Board of Trustees prior to the time that the interested shareholder becomes an interested shareholder. A person is not an interested shareholder under the statute if the board of trustees approves in advance the transaction by which that shareholder otherwise would have become an interested shareholder. The board of trustees may provide that its approval is subject to compliance with any terms and conditions determined by the board of trustees. Our Board of Trustees has adopted a resolution that any business combination between us and any other person is exempted from the provisions of the MGCL described in the preceding paragraphs, provided that the business combination is first approved by our Board of Trustees, including the approval of a majority of the members of our Board of Trustees who are not affiliates or associates of the interested shareholder. This resolution, however, may be altered or repealed in whole or in part at any time.

Control Share Acquisitions

        The MGCL contains a provision which regulates control share acquisitions. This provision applies to REITs formed under Maryland law like us. The MGCL provides that control shares of a REIT formed under Maryland law acquired in a control share acquisition have no voting rights except to the extent that the acquisition is approved by a vote of two thirds of the votes entitled to be cast on the matter, excluding shares owned by the acquiror, by officers or by trustees who are employees of the trust. Control shares are voting shares, which, if aggregated with all other shares previously acquired by the acquiror, or in respect of which the acquiror is able to exercise or direct the exercise of voting power (except solely by virtue of a revocable proxy), would entitle the acquiror to exercise voting power in electing trustees within one of the following ranges of voting power:

•

one tenth or more but less than one third;



•

one third or more but less than a majority; or



•

a majority or more of all voting power.

38

Table of Contents

        An acquiror must obtain the necessary shareholder approval each time it acquires control shares in an amount sufficient to cross one of the thresholds noted above.

        Control shares do not include shares which the acquiring person is entitled to vote as a result of having previously obtained shareholder approval. The MGCL provides for certain exceptions from the definition of control share acquisition.

        A person who has made or proposes to make a control share acquisition, upon satisfaction of the conditions set forth in the statute, including an undertaking to pay the expenses of the meeting, may compel the board of trustees of the trust to call a special meeting of shareholders to be held within 50 days of demand to consider the voting rights of the shares. If no request for a meeting is made, the trust may itself present the matter at any shareholders meeting.

        If voting rights are not approved at the meeting or if the acquiring person does not deliver an acquiring person statement as required by the MGCL, then the trust may redeem for fair value any or all of the control shares, except those for which voting rights have previously been approved. The right of the trust to redeem control shares is subject to conditions and limitations. Fair value is determined, without regard to the absence of voting rights for the control shares, as of the date of the last control share acquisition by the acquiror or of any meeting of shareholders at which the voting rights of the shares are considered and not approved. If voting rights for control shares are approved at a shareholders meeting and the acquiror becomes entitled to vote a majority of the shares entitled to vote, all other shareholders may exercise appraisal rights. The fair value of the shares as determined for purposes of appraisal rights may not be less than the highest price per share paid by the acquiror in the control share acquisition.

        The control share acquisition statute of the MGCL does not apply to the following:

•

shares acquired in a merger, consolidation or share exchange if the trust is a party to the transaction; or



•

acquisitions approved or exempted by a provision in the declaration of trust or bylaws of the trust adopted before the acquisition of shares.

        Our bylaws contain a provision exempting any and all acquisitions by any person of our common shares from the control share acquisition statute. This provision may be amended or eliminated at any time in the future.

Subtitle 8

        Subtitle 8 of Title 3 of the MGCL permits a Maryland REIT with a class of equity securities registered under the Exchange Act and at least three independent trustees to elect to be subject, by provision in its declaration of trust or bylaws or a resolution of its board of trustees and notwithstanding any contrary provision in the declaration of trust or bylaws, to any or all of five provisions:

•

a classified board;



•

a two thirds vote requirement for removing a trustee;



•

a requirement that the number of trustees be fixed only by vote of the trustees;



•

a requirement that a vacancy on the board be filled only by the remaining trustees in office and for the replacement trustee to serve for the remainder of the full term of the class of trustees in which the vacancy occurred; and



•

a majority requirement for the calling of a shareholder requested special meeting of shareholders.

39

Table of Contents

        Through other provisions in our declaration of trust and bylaws unrelated to Subtitle 8, we (1) require the affirmative vote of the holders of not less than two thirds of all of the votes entitled to be cast in the election of such Trustee for the removal of any Trustee from our Board of Trustees, which removal will be allowed only for cause, subject to conditions, (2) vest in our Board of Trustees the exclusive power to fix the number of our Trustees, (3) require that only our Board of Trustees may fill vacancies on our Board of Trustees, and (4) vest in our Board of Trustees the exclusive power to call meetings of our shareholders. We have made an election pursuant to Subtitle 8 to classify our Board of Trustees.

Amendments to Our Declaration of Trust, Dissolution and Mergers

        Under the Maryland REIT Law, a Maryland REIT generally cannot dissolve, amend its declaration of trust, convert or merge unless these actions are approved by at least two thirds of all shares entitled to be cast on the matter. The Maryland REIT Law allows a trust's declaration of trust to set a lower percentage, so long as the percentage is not less than a majority of the votes entitled to be cast on the matter. Our declaration of trust provides for approval of any of the foregoing actions (except amendments to certain provisions of the declaration of trust) by a majority of shares entitled to vote on these actions provided the action in question has been approved by a majority of our Board of Trustees. Our declaration of trust further provides that if permitted in the future by Maryland law, the majority required to approve any of the foregoing actions (subject to such exceptions) will be the majority of shares voted. Under the Maryland REIT Law, a declaration of trust may permit the trustees by a two thirds vote to amend the declaration of trust from time to time to qualify as a REIT under the Code or the Maryland REIT Law without the affirmative vote or written consent of the shareholders. Our declaration of trust permits this type of action by our Board of Trustees. Our declaration of trust also permits our Board of Trustees to increase or decrease the aggregate number of shares that we may issue and to effect changes in our unissued shares, as described more fully above, and to change our name, in each case without shareholder approval, and provides that, to the extent permitted in the future by Maryland law, our Board of Trustees may amend any other provision of our declaration of trust without shareholder approval. The Maryland REIT Law provides that a majority of our entire Board of Trustees, without action by the shareholders, may, among other things, amend our declaration of trust to change the name, other designation or the par value of any class or series of our shares and the aggregate par value of our shares. Our declaration of trust and bylaws also provide that our bylaws may only be amended by our Board of Trustees.

Anti-Takeover Effect of Maryland Law and of Our Declaration of Trust and Bylaws

        The following provisions in our declaration of trust and bylaws and in Maryland law could delay or prevent a change in our control:

•

the prohibition in our declaration of trust of any shareholder other than excepted holders and RMR LLC and its affiliates from owning more than 9.8% in value or in number, whichever is more restrictive, of any class or series of our outstanding shares, including our common shares;



•

the division of our Trustees into three classes, with the term of one class expiring each year and, in each case, until a successor is elected and qualifies;



•

shareholder voting rights and standards for the election of Trustees and other matters which generally require larger majorities for approval of actions which are not approved by our Trustees or for the election of Trustees in contested elections than for actions which are approved by our Trustees or for the election of Trustees in uncontested elections;



•

the authority of our Board of Trustees, and not our shareholders, to adopt, amend or repeal our bylaws and to fill vacancies on our Board of Trustees;

40

Table of Contents

•

the fact that only our Board of Trustees, or if there are no Trustees, our officers, may call shareholder meetings and that shareholders are not entitled to act without a meeting;



•

required qualifications for an individual to serve as a Trustee and a requirement that certain of our Trustees be Managing Trustees and other Trustees be Independent Trustees;



•

limitations on the ability of, and various requirements that must be satisfied in order for, our shareholders to propose nominees for election to our Board of Trustees and propose other business to be considered at a meeting of our shareholders;



•

the requirement that an individual Trustee may be removed only for cause, subject to conditions, by the affirmative vote of the holders of not less than two thirds of our common shares entitled to vote in the election of Trustees or, with or without cause, by the affirmative vote of all the remaining Trustees;



•

the authority of our Board of Trustees to adopt certain amendments to our declaration of trust without shareholder approval, including the authority to increase or decrease the number of authorized shares, to create new classes or series of shares (including a class or series of shares that could delay or prevent a transaction or a change in our control that might involve a premium for our shares or otherwise be in the best interests of our shareholders), to increase or decrease the number of shares of any class or series, and to classify or reclassify any unissued shares from time to time by setting or changing the preferences, conversion or other rights, voting powers, restrictions, limitations as to distributions, qualifications or terms or conditions of redemption of our shares or any new class or series of shares created by our Board of Trustees;



•

the requirement that amendments to our declaration of trust may be made only if approved by a majority of our Trustees;



•

the business combination provisions of the MGCL, if the applicable resolution of our Board of Trustees is rescinded or if our Board's approval of a combination is not obtained; and



•

the control share acquisition provisions of the MGCL, if the provision in our bylaws exempting acquisitions of our shares from such provisions is amended or eliminated.

        In addition, our revolving credit and term loan agreements and our shareholders agreement with AIC each also contain change in control provisions, which are further described below, and our business management and property management agreements with RMR LLC contain provisions that allow for termination for convenience and termination for a performance reason but require the payment of a termination fee, as further described in those agreements.

        For all of these reasons, among others, our shareholders may be unable to realize a change of control premium for any of our shares they own or otherwise effect a change of our policies.

Liability of Shareholders for Breach of Restrictions on Ownership

        Our revolving credit facility and term loan agreements provide that a change in our control, as defined in those agreements and including RMR LLC ceasing to act as our business and property manager, constitutes a default under those agreements, and a default under those agreements could result in a cross-default under our senior unsecured notes or our other debt. In addition, our shareholders agreement with respect to AIC provides that AIC and the other shareholders of AIC may have rights to acquire our interests in AIC if such an acquisition occurs or if we experience some other change in control. If a breach of the ownership limitations or other provisions of our declaration of trust or bylaws results in a default under our revolving credit facility or term loan agreements or our other debt or a loss of our ownership interests in AIC or other costs or expenses we may incur as a result of the breach, the shareholder or shareholders causing the breach may be liable to us and may be liable to our other shareholders for damages. These damages may be in addition to the loss of

41

Table of Contents

beneficial ownership and voting rights of the shares owned by the breaching shareholder or shareholders, as described above, and these damages may be material.