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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549

SCHEDULE 14A
Proxy Statement Pursuant to Section 14(a) of the Securities
Exchange Act of 1934 (Amendment No.    )

Senior Housing Properties Trust

(Name of Registrant as Specified In Its Charter)
(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

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Senior Housing Properties Trust

Notice of 2018 Annual Meeting
of Shareholders and Proxy Statement

Tuesday, May 22, 2018 at 9:30 a.m., Eastern time
Two Newton Place, 255 Washington Street, Suite 100, Newton, Massachusetts 02458

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Senior Housing Properties Trust

It is our pleasure to invite you to join our Board of Trustees and executive officers at Senior Housing Properties Trust's 2018 Annual Meeting of Shareholders in Newton, Massachusetts. The enclosed Notice of 2018 Annual Meeting of Shareholders and Proxy Statement provides you with information about our Company and the matters to be voted on at the 2018 Annual Meeting of Shareholders.

We are committed to effectively communicating with our shareholders and explaining the matters to be addressed at our 2018 Annual Meeting of Shareholders. This Proxy Statement includes a Question and Answer section with information that we believe may be useful to our shareholders.

Your support is important to us and to our Company. I encourage you to use telephone or internet methods, or sign and return a proxy card/voting instruction form, to authorize your proxy prior to the meeting so that your shares will be represented and voted at the meeting.

Thank you for being a shareholder and for your continued investment in our Company.

April 3, 2018

On behalf of the Board of Trustees,

Lisa Harris Jones
Chair of the Nominating and Governance Committee

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NOTICE OF 2018 ANNUAL MEETING OF SHAREHOLDERS

Tuesday, May 22, 2018

9:30 a.m., Eastern time

Two Newton Place, 255 Washington Street, Suite 100
Newton, Massachusetts 02458

ITEMS OF BUSINESS

1.

Elect the Trustee nominees identified in the accompanying Proxy Statement to the Company's Board of Trustees;

2.

Advisory vote to approve executive compensation;

3.

Ratify the appointment of Ernst & Young LLP as independent auditors to serve for the 2018 fiscal year; and

4.

Transact such other business as may properly come before the meeting and at any postponements or adjournments of the meeting.

RECORD DATE

The Board of Trustees set February 1, 2018 as the record date for the meeting. This means that owners of record of the common shares of the Company as of the close of business on that date are entitled:

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to receive notice of the meeting; and



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to vote at the meeting and any postponements or adjournments of the meeting.

PROXY VOTING

Shareholders as of the close of business on the record date are invited to attend the 2018 Annual Meeting. All shareholders are encouraged to vote in advance of the 2018 Annual Meeting by using one of the methods described in the accompanying Proxy Statement.

April 3, 2018
Newton, Massachusetts

By Order of the Board of Trustees,

Jennifer B. Clark
Secretary

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VOTING INFORMATION

WE WANT TO HEAR FROM YOU – VOTE TODAY

Your vote is important.

ELIGIBILITY TO VOTE

You can vote if you were a shareholder of record at the close of business on February 1, 2018.

PROPOSALS THAT REQUIRE YOUR VOTE

You can vote in advance in one of three ways:

If the meeting is postponed or adjourned, these times will be extended to 11:59 p.m., Eastern time, on the day before the reconvened meeting.

PLEASE VISIT: www.proxyvote.com

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Review and download easy to read versions of our Proxy Statement and Annual Report.

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Sign up for future electronic delivery to reduce the impact on the environment.

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PROXY SUMMARY

This summary highlights matters for consideration by shareholders at our 2018 Annual Meeting. You should read this entire Proxy Statement carefully before voting. Page references are supplied to help you find further information in this Proxy Statement.

BOARD NOMINEES (page 17)

The following two Trustees are up for election to our Company's Board of Trustees.

ADVISORY VOTE TO APPROVE EXECUTIVE COMPENSATION (page 60)

Shareholders are asked to approve the executive compensation of the Company's named executive officers through a non-binding advisory vote. In evaluating the executive compensation paid by the Company in 2017, the Compensation Committee considered that the Company has no employees and the Company's manager, The RMR Group LLC ("RMR LLC"), conducts the day to day operations of the Company and provides the services that otherwise would be provided by employees, including employing and compensating the Company's executive officers. RMR LLC is compensated for its services to the Company pursuant to business and property management agreements and the Company does not reimburse RMR LLC for compensation that RMR LLC pays to the Company's executive officers. In this evaluation, the Company also generally considered the results of the advisory vote of the Company's shareholders on the compensation of the executive officers named in the proxy statement for the Company's 2017 annual meeting of shareholders.

RATIFICATION OF THE APPOINTMENT OF ERNST & YOUNG LLP AS INDEPENDENT AUDITORS (page 61)

Shareholders are asked to ratify the appointment of Ernst & Young LLP as independent auditors of Senior Housing Properties Trust for the Company's fiscal year ending December 31, 2018. The Company's Audit Committee evaluates the performance of the Company's independent auditors and determines whether to reengage the current independent auditors or consider other audit firms. In doing so, the Audit Committee considers the quality and efficiency of the services provided by the auditors, the auditors' technical expertise and knowledge of the Company's operations and industry, the auditors' independence, legal proceedings involving the auditors, the results of PCAOB inspections and peer quality reviews of the auditors and the auditors' reputation in the marketplace. Based on its consideration of these matters, the Audit Committee has appointed Ernst & Young LLP to serve as the Company's independent auditors for the fiscal year ending December 31, 2018.

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GOVERNANCE HIGHLIGHTS (page 27)

The Company is committed to good corporate governance, which promotes the long term interests of its shareholders, strengthens the Board, increases management's accountability and helps build public trust in the Company. This commitment is reflected in various aspects of the Company's corporate governance, including:

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TWO NEWTON PLACE
255 WASHINGTON STREET, SUITE 300
NEWTON, MASSACHUSETTS 02458

April 3, 2018

PROXY STATEMENT

The Board of Trustees (the "Board") is furnishing this Proxy Statement to solicit proxies to be voted at the 2018 Annual Meeting of Shareholders (the "2018 Annual Meeting") of Senior Housing Properties Trust, a Maryland real estate investment trust (together with its direct or indirect subsidiaries, the "Company," "we," "us" or "our"). The meeting will be held at Two Newton Place, 255 Washington Street, Suite 100, Newton, Massachusetts 02458 on Tuesday, May 22, 2018, at 9:30 a.m., Eastern time.

The mailing address of the Company's principal executive offices is Two Newton Place, 255 Washington Street, Suite 300, Newton, Massachusetts 02458. The Company commenced mailing to its shareholders a Notice Regarding the Availability of Proxy Materials containing instructions on how to access the Company's Proxy Statement and its 2017 Annual Report on Form 10-K on or about April 3, 2018.

All properly executed written proxies, and all properly completed proxies submitted by telephone or internet, that are delivered pursuant to this solicitation will be voted at the 2018 Annual Meeting in accordance with the directions given in the proxy, unless the proxy is revoked prior to it being exercised at the meeting. These proxies also may be voted at any postponements or adjournments of the meeting.

Only owners of record of common shares of beneficial interest, par value $0.01 per share, of the Company ("Common Shares") as of the close of business on February 1, 2018, the record date for the meeting (the "Record Date"), are entitled to notice of, and to vote at, the meeting and at any postponements or adjournments of the meeting. Holders of Common Shares are entitled to one vote for each Common Share held on the Record Date. On February 1, 2018, there were approximately 237,625,781 Common Shares issued and outstanding.

   

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QUESTIONS AND ANSWERS

Proxy Materials and Voting Information

The proxy materials for the 2018 Annual Meeting include the Notice Regarding the Availability of Proxy Materials, Notice of 2018 Annual Meeting, this Proxy Statement and the Company's Annual Report on Form 10-K for the fiscal year ended December 31, 2017 (the "Annual Report" and, together with the other materials, the "proxy materials"). If you request a paper copy of these materials, the proxy materials will also include a proxy card or voting instruction form.

A proxy statement is a document that the Securities and Exchange Commission ("SEC") regulations require the Company to give you when it asks you to return a proxy designating individuals to vote on your behalf. A proxy is your legal designation of another person to vote the shares you own. That other person is called your proxy. We are asking you to designate the following three persons as your proxies for the 2018 Annual Meeting: Jennifer B. Clark, Managing Trustee and Secretary; Adam D. Portnoy, Managing Trustee; and Richard W. Siedel, Chief Financial Officer and Treasurer.

If your shares are registered directly in your name with the Company's registrar and transfer agent, Equiniti Trust Company (formerly known as Wells Fargo Shareowner Services), you are considered a shareholder of record of those shares. If you are a shareholder of record, you should receive only one notice or proxy card for all the Common Shares you hold in certificate form and in book entry form.

If your shares are held in an account you own at a bank or brokerage or you hold shares through another nominee, you are considered the "beneficial owner" of those shares. If you are a beneficial owner, you will receive voting instruction information from the bank, broker or other nominee through which you own your Common Shares.

If you hold some shares of record and some shares beneficially, you should receive a notice or proxy card for all the Common Shares you hold of record and a separate voting instruction form for the shares from the bank, broker or other nominee through which you own Common Shares.

By Written Proxy. All shareholders of record can submit voting instructions by written proxy card. If you are a shareholder of record and receive a Notice Regarding the Availability of Proxy Materials, you may request a written proxy card by following the instructions included in the notice. If you are a beneficial owner, you may request a written proxy card or a voting instruction form from your bank, broker or other nominee. Proxies submitted by mail must be received by 11:59 p.m., Eastern time, on May 21, 2018 or, if the meeting is postponed or adjourned to a later date, by 11:59 p.m., Eastern time, on the day immediately preceding the date of the reconvened meeting.

By Telephone or Internet. All shareholders of record also can authorize a proxy to vote their shares by touchtone telephone by calling 1-800-690-6903, or through the internet at www.proxyvote.com, using the procedures and instructions described in your Notice Regarding the Availability of Proxy Materials or

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proxy card. Beneficial owners may authorize a proxy by telephone or internet if their bank, broker or other nominee makes those methods available, in which case the bank, broker or nominee will include the instructions with the proxy voting materials. To authorize a proxy by telephone or internet, you will need the 16 digit control number provided on your Notice Regarding the Availability of Proxy Materials, proxy card or voting instruction form. The telephone and internet proxy authorization procedures are designed to authenticate shareholder identities, to allow shareholders to vote their shares and to confirm that their instructions have been recorded properly. Proxies submitted by telephone or through the internet must be received by 11:59 p.m., Eastern time, on May 21, 2018 or, if the meeting is postponed or adjourned to a later date, by 11:59 p.m., Eastern time, on the day immediately preceding the date of the reconvened meeting.

In Person. All shareholders of record may vote in person at the meeting. Beneficial owners may vote in person at the meeting if they have a legal proxy, as described in the response to question 15.

If you have any questions or need assistance in voting your shares or authorizing your proxy, please call the firm assisting the Company in the solicitation of proxies:

Morrow Sodali LLC
470 West Avenue
Stamford, Connecticut 06902
Shareholders Call Toll Free: (800) 662-5200
Banks and Brokers Call Collect: (203) 658-9400

Holders of record of Common Shares as of the close of business on February 1, 2018, the Record Date, may vote at the meeting. Holders of Common Shares are entitled to one vote for each Common Share held on the Record Date.

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If you return a signed proxy card or authorize a proxy by internet or telephone and do not specify a choice for a matter, you will be instructing your proxy to vote in the manner recommended by the Board on that matter:

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FOR the election of both Trustee nominees identified in this Proxy Statement;



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FOR the advisory vote to approve executive compensation; and



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FOR the ratification of the appointment of Ernst & Young LLP as independent auditors.

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If you are a beneficial owner and do not provide voting instructions to your bank, broker or other nominee, the following applies:

Non-Discretionary Items. The election of the Trustees and the advisory vote to approve executive compensation are non-discretionary items and may not be voted on by brokers, banks or other nominees who have not received specific voting instructions from beneficial owners. The result of the inability of a broker, bank or other nominee to vote on a non-discretionary item for which it has not received specific voting instructions from beneficial owners is referred to as a broker non-vote.

Discretionary Items. The ratification of the appointment of Ernst & Young LLP as independent auditors is a discretionary item. Generally, banks, brokers and other nominees that do not receive voting instructions from beneficial owners may vote on this proposal in their discretion.

A quorum of shareholders is required for shareholders to take action at the 2018 Annual Meeting. The presence, in person or by proxy, of shareholders entitled to cast a majority of all the votes entitled to be cast at the 2018 Annual Meeting constitutes a quorum.

Abstentions and broker non-votes are included in determining whether a quorum is present. Abstentions are not votes cast and, therefore, will not be included in vote totals and will have no effect on the outcome of any Item to be voted on at the 2018 Annual Meeting. Broker non-votes are not votes cast and, therefore, will not be included in vote totals and will have no effect on the outcome of Items 1 or 2. There can be no broker non-votes on Item 3 as it is a matter on which, if you hold your shares in street name and do not provide voting instructions to the broker, bank or other nominee that holds your shares, the nominee has discretionary authority to vote on your behalf.

With respect to Item 1, a proxy marked "WITHHOLD" will have the same effect as an abstention and will not be counted for purposes of determining a plurality of votes cast, but will be counted as a vote "AGAINST" for purposes of determining a majority of votes cast under the Company's Trustee resignation policy. Pursuant to the Company's Governance Guidelines, if a Trustee nominee fails to receive a majority of votes cast, she will offer to resign from the Board and the Board will decide whether to accept or reject the resignation offer.

Shareholders have the right to revoke a proxy at any time before it is voted at the 2018 Annual Meeting, subject to the proxy voting deadlines described above. Shareholders may revoke a proxy by authorizing a proxy again on a later date by internet or by telephone (only the last internet or telephone proxy submitted prior to the meeting will be counted) or by signing and returning a later dated proxy card or by attending the meeting and voting in person. If you are a beneficial owner, see the response to question 15.

A shareholder's attendance at the 2018 Annual Meeting will not revoke that shareholder's proxy unless that shareholder votes again at the meeting or sends an original written statement to the Secretary of the Company revoking the prior proxy. An original written notice of revocation or subsequent proxy should be delivered to Senior Housing Properties Trust, Two Newton Place, 255 Washington Street, Suite 300, Newton, Massachusetts 02458, Attention: Secretary, or hand delivered to the Secretary before the taking of the vote at the 2018 Annual Meeting.

Beneficial owners who wish to change their votes should contact the organization that holds their shares.

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The Notice of 2018 Annual Meeting, this Proxy Statement and the Annual Report are available at www.proxyvote.com. You may access these proxy materials on the internet through the conclusion of the 2018 Annual Meeting.

Instead of receiving future copies of the Company's proxy materials by mail, shareholders of record and most beneficial owners may elect to receive these materials electronically. Opting to receive your future proxy materials electronically will save us the cost of printing and mailing documents, and also will give you an electronic link to our proxy voting site. Your Notice Regarding the Availability of Proxy Materials instructs you as to how you may request electronic delivery of future proxy materials.

The Company will report the final results in a Current Report on Form 8-K filed with the SEC following the completion of the 2018 Annual Meeting.

The Company bears all expenses incurred in connection with the solicitation of proxies. The Company has engaged Morrow Sodali LLC ("Morrow") to assist with the solicitation of proxies for an estimated fee of $20,000 plus reimbursement of expenses. The Company has agreed to indemnify Morrow against certain liabilities arising out of the Company's agreement with Morrow. We will request banks, brokers and other nominees to forward proxy materials to the beneficial owners of Common Shares and to obtain their voting instructions. We will reimburse those firms for their expenses of forwarding proxy materials.

Proxies may also be solicited, without additional compensation, by the Company's Trustees and officers, and by The RMR Group LLC ("RMR LLC"), its officers and employees and its parent's and subsidiaries' directors, officers and employees, by mail, telephone or other electronic means or in person.

As permitted by the Securities Exchange Act of 1934, as amended (the "Exchange Act"), we may deliver only one copy of the Notice Regarding the Availability of Proxy Materials, Notice of 2018 Annual Meeting, this Proxy Statement and the Annual Report to Shareholders residing at the same address, unless the shareholders have notified us of their desire to receive multiple copies of those documents. This practice is known as "householding."

We will deliver a separate copy of any of those documents to you if you write to the Company at Investor Relations, Senior Housing Properties Trust, Two Newton Place, 255 Washington Street, Suite 300, Newton, Massachusetts 02458, or call the Company at (617) 796-8234. If you want to receive separate copies of our notices regarding the availability of proxy materials, notices of annual meetings, proxy statements and annual reports in the future, or if you are receiving multiple copies and would like to receive only one copy per household, you should contact your bank, broker or other nominee, or you may contact us at the above address or telephone number.

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2018 Annual Meeting Information

All attendees need to bring photo identification for admission. Please note that cameras and audio or video recorders are not permitted at the meeting. Any cell phones, pagers or similar electronic devices must be shut off for the duration of the meeting.

Attendance at the meeting is limited to the Company's Trustees and officers, shareholders as of the Record Date (February 1, 2018) or their duly authorized representatives or proxies, and other persons permitted by the Chairman of the meeting.

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Record owners: If you are a shareholder as of the Record Date who holds shares directly, you need not present any documentation to attend the 2018 Annual Meeting, other than photo identification.



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Beneficial owners: If you are a shareholder as of the Record Date who holds shares indirectly through a brokerage firm, bank or other nominee, you may be required to present evidence of your beneficial ownership of shares. For this purpose, a letter or account statement from the applicable brokerage firm, bank or other nominee confirming such ownership will be acceptable. Please note that you will not be able to vote your shares at the meeting without a legal proxy, as described in the response to question 15.



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Authorized named representatives: If you are a shareholder as of the Record Date and intend to appoint an authorized named representative to attend the meeting on your behalf, including if you are a corporation, partnership, limited liability company or other entity, you must notify us of your intent by regular mail to our Secretary or by email to secretary@snhreit.com. Requests for authorized named representatives to attend the meeting must be received no later than Tuesday May 15, 2018, or if the meeting is postponed or adjourned to a later date, on or before the 5^th business day before the reconvened meeting.

Please include the following information when submitting your request:

(1)

Your name and complete mailing address;

(2)

Proof that you owned shares of the Company as of February 1, 2018 (such as a copy of the portion of your voting instruction form showing your name and address, a bank or brokerage firm account statement or a letter from the bank, broker or other nominee holding your shares); and

(3)

A signed authorization appointing such individual to be your authorized named representative at the meeting, which includes the name, address, telephone number and email address of the authorized named representative.

Upon receipt of proper documentation, you and your named representative will receive confirmation that your named representative has been authorized to attend the meeting. For admission to the meeting, the photo ID presented must match the documentation provided in response to item (3) above. The Company reserves the right to limit the number of representatives who may attend the meeting.

If you have questions regarding these admission procedures, please call Investor Relations at (617) 796-8234.

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If you are a beneficial owner and want to vote your shares at the 2018 Annual Meeting, you need a legal proxy from your bank, broker or other nominee. You also need to follow the procedures described in the response to question 14 and to bring the legal proxy with you to the meeting and hand it in with a signed ballot that will be provided to you at the meeting. You will not be able to vote your shares at the meeting without a legal proxy. If you do not have a legal proxy, you can still attend the meeting by following the procedures described in the response to question 14. However, you will not be able to vote your shares at the meeting without a legal proxy. The Company encourages you to vote your shares in advance, even if you intend to attend the meeting.

Company Documents, Communications and Shareholder Proposals

You can visit our website to view our Governance Guidelines, Board committee charters and Code of Business Conduct and Ethics (the "Code"). To view these documents, go to www.snhreit.com, click on "Investors" and then click on "Governance." To view the Company's SEC filings and Forms 3, 4 and 5 filed by the Company's Trustees and executive officers, go to www.snhreit.com, click on "Investors," click on "Financial Information" and then click on "SEC Filings."

We will deliver free of charge, upon request, a copy of the Company's Governance Guidelines, Board committee charters, Code or Annual Report to any shareholder requesting a copy. Requests should be directed to Investor Relations at Two Newton Place, 255 Washington Street, Suite 300, Newton, Massachusetts 02458.

Any shareholder or other interested person who wants to communicate with the Company's Trustees, individually or as a group, should write to the party for whom the communication is intended, c/o Secretary, Senior Housing Properties Trust, Two Newton Place, 255 Washington Street, Suite 300, Newton, Massachusetts 02458 or email secretary@snhreit.com. The communication will then be delivered to the appropriate party or parties.

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A proposal for action to be presented by any shareholder at the Company's 2019 annual meeting of shareholders must be submitted as follows:

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For a proposal to be eligible to be included in the proxy statement pursuant to Rule 14a-8 under the Exchange Act, the proposal must be received at the Company's principal executive offices by December 4, 2018.

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If the proposal is not to be included in the proxy statement pursuant to Rule 14a-8, the proposal must be made in accordance with the procedures and requirements set forth in our Amended and Restated Bylaws (our "Bylaws") and must be received by the Company not later than 5:00 p.m., Eastern time, on December 4, 2018 and not earlier than November 4, 2018.

Proposals should be sent to the Company's Secretary at Two Newton Place, 255 Washington Street, Suite 300, Newton, Massachusetts 02458.

For additional information regarding how to submit a shareholder proposal, see page 36 of this Proxy Statement.

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ELECTION OF TRUSTEES (ITEM 1)

The Board serves as the decision making body of the Company, except for those matters reserved to the shareholders. The Board selects and oversees the Company's officers, who are charged by the Board with conducting the day to day business of the Company.

In accordance with our Amended and Restated Declaration of Trust (our "Declaration of Trust") and Bylaws, the Board currently consists of five members, three of whom are Independent Trustees and two of whom are Managing Trustees. Our Declaration of Trust, as supplemented by Articles Supplementary filed with the State Department of Assessments and Taxation of Maryland on June 30, 2017, provides that the Board is divided into three classes, with each Trustee of each class elected at an annual meeting of shareholders serving for a term that continues until the third annual meeting of shareholders following his or her election and until his or her successor is elected and qualifies. In accordance with our Declaration of Trust and Bylaws, on March 29, 2018, pursuant to a recommendation of the Nominating and Governance Committee, the Board elected Jennifer B. Clark as a Managing Trustee in Class I to fill the vacancy created by the death of Barry M. Portnoy on February 25, 2018 and to serve the remainder of the full term of the Class I Trustees, the Class of Trustees which stands for election at the 2018 Annual Meeting.

Assuming a quorum is present at the meeting, a plurality of all the votes cast is required to elect a Trustee at the 2018 Annual Meeting. Pursuant to the Company's 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. In such circumstance, the Nominating and Governance Committee will make a recommendation to the Board as to whether to accept or reject the resignation offer. The Board will act on the resignation offer taking into account the recommendation of the Nominating and Governance Committee and make its decision within 90 days following the certification of the election results.

The Nominating and Governance Committee is responsible for identifying and evaluating nominees for Trustee and for recommending to the Board nominees for election at each annual meeting of shareholders. The Nominating and Governance Committee may consider candidates suggested by the Company's Trustees, officers or shareholders or by others.

Shareholder Recommendations for Nominees. Shareholders who would like to recommend a nominee for the position of Trustee should submit their recommendations in writing by mail to the Chair of the Nominating and Governance Committee, c/o Senior Housing Properties Trust, Secretary, at Two Newton Place, 255 Washington Street, Suite 300, Newton, Massachusetts 02458 or by email to secretary@snhreit.com. A shareholder's recommendation should include any information that the recommending shareholder believes relevant to the Nominating and Governance Committee's consideration. The Nominating and Governance Committee may request additional information about the shareholder recommended nominee or about the shareholder recommending the nominee. Recommendations by shareholders will be considered by the Nominating and Governance Committee in its discretion using the same criteria as other candidates it considers.

Shareholder Nominations for Trustee. Our Bylaws also provide that a shareholder of the Company may nominate a person for election to the Board provided the shareholder complies with the advance notice provisions set forth in our Bylaws, which include, among other things, requirements as to the proposing shareholder's timely delivery of advance notice, continuous requisite ownership of Common Shares and submission of specified documentation and information. For more information on how shareholders can

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nominate Trustees for election to the Board, see "Shareholder Nominations and Other Proposals" beginning on page 36.

Trustees are responsible for overseeing the Company's business. This significant responsibility requires highly skilled individuals with various qualities, attributes and professional experience. The Board believes that there are general requirements that are applicable to all Trustees, qualifications applicable to Independent Trustees and other skills and experience that should be represented on the Board as a whole, but not necessarily by each Trustee. In accordance with our Declaration of Trust and Bylaws, the Board currently consists of five Trustees: two Managing Trustees and three Independent Trustees. As set forth in our Bylaws, Independent Trustees are Trustees who are not employees of RMR LLC, who are not involved in the Company's day to day activities and who meet the qualifications of independent directors under the applicable rules of The Nasdaq Stock Market LLC (the "Nasdaq") and the SEC. As set forth in our Bylaws, Managing Trustees are Trustees who have been employees, officers or directors of RMR LLC or who have been involved in the Company's day to day activities for at least one year prior to their election as Trustees. The Board and the Nominating and Governance Committee consider the qualifications of Trustees and Trustee candidates individually and in the broader context of the Board's overall composition and the Company's current and future needs.

Qualifications for All Trustees

In its assessment of each potential candidate, including those recommended by shareholders, the Nominating and Governance Committee considers the potential nominee's integrity, experience, achievements, judgment, intelligence, competence, personal character, likelihood that a candidate will be able to serve on the Board for an extended period and other matters that the Nominating and Governance Committee deems appropriate. The Nominating and Governance Committee also takes into account the ability of a potential nominee to devote the time and effort necessary to fulfill his or her responsibilities to the Company.

The Board and Nominating and Governance Committee require that each Trustee candidate be a person of high integrity with a proven record of success in his or her field. Each Trustee candidate must demonstrate the ability to make independent analytical inquiries, familiarity with and respect for corporate governance requirements and practices and a commitment to serving the Company's long term best interests. In addition, the Nominating and Governance Committee may conduct interviews of potential Trustee candidates to assess intangible qualities, including the individual's ability to ask appropriate questions and to work collegially. The Board does not have a specific diversity policy in connection with the selection of nominees for Trustee, but due consideration is given to the Board's overall balance of diversity, including professional background, experience, perspective, gender and ethnicity.

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Specific Qualifications, Attributes, Skills and Experience to be Represented on the Board

The Board has identified particular qualifications, attributes, skills and experience that are important to be represented on the Board as a whole, in light of the Company's long term interests. The following table summarizes certain key characteristics of the Company's business and the associated qualifications, attributes, skills and experience that the Board believes should be represented on the Board.

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The following table sets forth the names of the Trustee nominees and those Trustees who will continue to serve after the 2018 Annual Meeting:

Upon the recommendation of the Nominating and Governance Committee, the Board has nominated Ms. Lisa Harris Jones for election as an Independent Trustee in Class I and Jennifer B. Clark for election as a Managing Trustee in Class I. Each Trustee nominee currently serves on the Board. If elected, each nominee would serve until the Company's 2021 annual meeting of shareholders and until her successor is duly elected and qualifies, subject to the individual's earlier death, resignation, retirement, disqualification or removal.

We expect that each nominee for election as a Trustee will be able to serve if elected. However, if a nominee should become unable or unwilling to serve, proxies may be voted for the election of a substitute nominee designated by the Board.

The Board believes that the combination of the various qualifications, attributes, skills and experiences of the Trustee nominees would contribute to an effective Board serving the Company's long term best interests. The Board and the Nominating and Governance Committee believe that the Trustee nominees possess the necessary qualifications to provide effective oversight of the business and quality advice and counsel to the Company's management. Below is a summary of the key experiences, qualifications, attributes and skills that led the Nominating and Governance Committee and the Board to conclude each such person is currently qualified to serve as a Trustee.

The Board of Trustees recommends a vote "FOR" the election of both Trustee nominees.

The following is some important biographical information, including the ages and recent principal occupations, as of March 30, 2018, of the Company's Trustees, Trustee nominees and executive officers. The business address of the Trustees, Trustee nominees and executive officers is c/o Senior Housing Properties Trust, Two Newton Place, 255 Washington Street, Suite 300, Newton, Massachusetts 02458. Included in each Trustee's biography below are the attributes of that Trustee consistent with the qualifications, attributes, skills and experience the Board has determined are important to be represented on the Board. For a general discussion of the particular Trustee qualifications, attributes, skills and experience, and the process for selecting and nominating individuals for election to serve as a Trustee, please see "Election of Trustees" beginning on page 14.

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Trustee Nominees

Lisa Harris Jones

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Jennifer B. Clark

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Trustees

John L. Harrington

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Adam D. Portnoy

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Jeffrey P. Somers

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Executive Officers

David J. Hegarty

Richard W. Siedel, Jr.

There are no family relationships among any of the Company's Trustees or executive officers. The Company's executive officers serve at the discretion of the Board.

RMR LLC or its subsidiaries provide management services to public and private companies, including the Company, Government Properties Income Trust, Hospitality Properties Trust, Industrial Logistics Properties Trust, Select Income REIT, Tremont Mortgage Trust, Five Star Senior Living Inc., TravelCenters of America LLC, Sonesta International Hotels Corporation and Affiliates Insurance Company. Government Properties Income Trust is a public REIT that primarily invests in properties that are majority leased to government tenants and office properties in the metropolitan Washington, D.C. market area that are leased to government and private sector tenants ("GOV"). Hospitality Properties Trust is a public REIT that owns hotels and travel centers ("HPT"). Industrial Logistics Properties Trust is a public REIT that owns industrial and logistics properties ("ILPT"). Select Income REIT is a public REIT that primarily owns net leased, single tenant properties ("SIR"). Tremont Mortgage Trust is a public REIT that focuses primarily on originating and investing in first mortgage loans secured by middle market and transitional CRE ("TRMT" and, together with GOV, HPT, ILPT and SIR, the "Other RMR Managed REITs"). Five Star Senior Living Inc. is a public real estate based operating company in the healthcare and senior living services business ("FVE"). TravelCenters of America LLC is a public real estate based operating company in the travel center, convenience store and restaurant businesses ("TA"). Sonesta International Hotels Corporation is a private company that operates and franchises hotels, resorts and cruise ships ("Sonesta"). Affiliates Insurance Company is a private Indiana insurance company ("AIC"). RMR LLC is a majority owned subsidiary of RMR Inc., a public company whose controlling shareholder is ABP Trust, which is controlled by its sole trustee, Adam D. Portnoy, one of our Managing Trustees, and to which RMR LLC provides management services. RMR Advisors LLC, a subsidiary of RMR LLC, is an SEC registered investment adviser to the RMR Real Estate Income Fund, which is an investment company registered under the Investment Company Act of 1940, as amended ("RIF"). Tremont Realty

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Advisors LLC, a subsidiary of RMR LLC, is an SEC registered investment adviser that provides investment advisory services to its investment advisory clients, which include TRMT, a private fund and separately managed accounts that invest in CRE debt, including secured mortgage debt and mezzanine financing opportunities. Tremont Realty Advisors LLC also provides management services to certain of its investment advisory clients, including originating, underwriting, closing and managing certain real estate loans or other real estate investments. Tremont Realty Advisors LLC, as an intermediary, also provides mortgage brokerage services, originating and arranging CRE loans for third parties who are not investment advisory clients. The foregoing entities may be considered to be affiliates of the Company.

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TRUSTEE COMPENSATION

The Compensation Committee is responsible for reviewing and determining the Common Share awards granted to Trustees and making recommendations to the Board regarding cash compensation paid to Trustees, in each case, for Board, committee and committee chair services. Managing Trustees do not receive cash compensation for their services as Trustees but do receive Common Share awards for their Board service. The number of Common Shares awarded to each Managing Trustee for Board service is the same as the number awarded to each Independent Trustee.

All Trustees receive compensation in Common Shares to align the interests of Trustees with those of the Company's shareholders. To this end, the Company's Governance Guidelines codify our expectation that, subject to certain exemptions, each Trustee retain at least 20,000 Common Shares by the later of: (i) the date of the 2019 annual meeting of shareholders of the Company and (ii) five years from the annual meeting of shareholders of the Company at which the Trustee was initially elected or, if earlier, the first annual meeting of shareholders of the Company following the initial appointment of the Trustee to the Board.

In determining the amount and composition of our Trustees' compensation, the Compensation Committee and the Board take various factors into consideration, including, but not limited to, the responsibilities of Trustees generally, as well as for service on committees and as committee chairs, and the forms of compensation paid to trustees or directors by comparable companies, including the compensation of trustees and directors of other companies managed by RMR LLC or its subsidiaries. The Board reviews the Compensation Committee's recommendations regarding Trustee cash compensation and determines the amount of such compensation.

In 2017, each Independent Trustee received an annual fee of $40,000 for services as a Trustee, plus a fee of $1,250 for each meeting attended. Up to two $1,250 fees were paid if a Board meeting and one or more Board committee meetings, or two or more Board committee meetings, were held on the same date. Each Independent Trustee and Managing Trustee received an award of 3,000 Common Shares in 2017.

Each Independent Trustee who served as a committee chair of the Board's Audit, Compensation or Nominating and Governance Committees received an additional annual fee of $15,000, $10,000 and $10,000, respectively. The Lead Independent Trustee received an additional annual cash retainer fee of $12,500 for serving in this role. Trustees were reimbursed for travel expenses they incurred in connection with their duties as Trustees and for out of pocket costs they incurred in connection with their attending certain continuing education programs.

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The following table details the total compensation of the Trustees for the year ended December 31, 2017 for services as a Trustee.

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CORPORATE GOVERNANCE

The Board is committed to corporate governance that promotes the long term interests of our shareholders. The Board has established Governance Guidelines that provide a framework for effective governance. The guidelines address matters such as general qualification standards for the Board, Trustee responsibilities, Board meetings and communications, Board committees, Trustee access to management and independent advisers, Trustee compensation and share ownership guidelines, Trustee orientation and continuing education, executive development and succession planning, related person transactions, annual performance evaluation of the Board and other matters. The Board regularly reviews developments in corporate governance and updates our Governance Guidelines and other governance materials as it deems necessary and appropriate.

The governance section of our website makes available our corporate governance materials, including the Governance Guidelines, the charter for each Board committee, the Code and information about how to report matters directly to management, the Board or the Audit Committee. To access these documents on the Company's website, www.snhreit.com, click on "Investors" and then click on "Governance." In addition, instructions on how to obtain copies of the Company's corporate governance materials are included in the response to question 16 in the "Questions and Answers" section on page 12.

In accordance with our Declaration of Trust and Bylaws, the Board is currently comprised of five Trustees, including three Independent Trustees and two Managing Trustees. All Trustees play an active role in overseeing the Company's business both at the Board and committee levels. As set forth in the Company's Governance Guidelines, the core responsibility of our Trustees is to exercise sound, informed and independent business judgment in overseeing the Company and its strategic direction. Our Trustees are skilled and experienced leaders and currently serve or have served as members of senior management in public and private for profit organizations and law firms, and have also served in academia. Our Trustees may be called upon to provide solutions to various complex issues and are expected to, and do, ask hard questions of the Company's officers and advisors. The Board is small, which facilitates informal discussions and communication from management to the Board and among Trustees.

We do not have a Chairman of the Board. In 2015, the Board amended the Company's Governance Guidelines to provide for the role and responsibilities of a Lead Independent Trustee to be selected annually by a majority of the Independent Trustees, and our Independent Trustees selected Mr. Somers to serve in such role. Among other things, the Lead Independent Trustee's responsibilities include: serving as a liaison between the Company's management and the Independent Trustees; presiding at all meetings of the Board at which the Managing Trustees are not present, including each executive session of the Independent Trustees; assisting the Compensation Committee in its annual evaluation of the performance of the Company's management; being reasonably available for consultation and direct communication with shareholders upon request; and such other responsibilities as the Board may determine. The Lead Independent Trustee may call meetings of the Independent Trustees or executive sessions of Independent Trustees and presides at any such meeting.

Our President and Treasurer are not members of the Board, but they regularly attend Board and Board committee meetings, as does our Director of Internal Audit. Other officers of RMR LLC also sometimes attend Board meetings at the invitation of the Board. Special meetings of the Board may be called at any time by any Managing Trustee, the President or pursuant to the request of any two Trustees then in office. Our Managing Trustees, in consultation with the Company's management and the Director of Internal Audit, set the agenda for Board meetings. The Lead Independent Trustee may place an item on an agenda, and any other Independent Trustee may suggest agenda items by submitting such a request

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to the Lead Independent Trustee. Discussions at Board meetings are led by the Managing Trustee or Independent Trustee who is most knowledgeable on a subject.

Pursuant to the Company's Governance Guidelines, the Company's Independent Trustees are expected to meet in regularly scheduled meetings at which only Independent Trustees are present. It is expected that these executive sessions may occur at least twice per year. Our Independent Trustees also meet separately with the Company's officers, with the Company's Director of Internal Audit and with the Company's independent auditors.

In 2017, the Board held eight meetings. In 2017, each then Trustee attended 75% or more of the aggregate of all meetings of the Board and the committees on which he or she served. All of the then Trustees attended last year's annual meeting of shareholders. The Company's policy with respect to Board members' attendance at meetings of the Board and annual meetings of shareholders can be found in the Company's Governance Guidelines, the full text of which appears at the Company's website, www.snhreit.com.

Under the corporate governance listing standards of the Nasdaq, the Board must consist of a majority of Independent Trustees. To be considered independent:

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a trustee must not have a disqualifying relationship, as defined in the corporate governance section of the Nasdaq rules; and



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the Board must affirmatively determine that the trustee otherwise has no relationship which would interfere with the exercise of independent judgment in carrying out the responsibilities of a trustee. To facilitate the trustee independence assessment process, the Board has adopted written Governance Guidelines as described below.

Our Bylaws also require that a majority of the Board be Independent Trustees. Under our Bylaws, Independent Trustees are Trustees who are not employees of RMR LLC, are not involved in the Company's day to day activities and who meet the qualifications of independent directors under the applicable rules of the Nasdaq and the SEC.

The Board affirmatively determines whether Trustees have a direct or indirect material relationship with the Company, including the Company's subsidiaries, other than serving as the Company's Trustees or trustees or directors of the Company's subsidiaries. In making independence determinations, the Board observes the Nasdaq and SEC criteria, as well as the criteria set forth in our Bylaws. When assessing a Trustee's relationship with the Company, the Board considers all relevant facts and circumstances, not merely from the Trustee's standpoint, but also from that of the persons or organizations with which the Trustee has an affiliation. Based on this review, the Board has determined that John L. Harrington, Lisa Harris Jones and Jeffrey P. Somers currently qualify as independent trustees under applicable Nasdaq and SEC criteria and as Independent Trustees under our Bylaws. In making these independence determinations, the Board reviewed and discussed additional information provided by the Trustees and the Company with regard to each of the Trustees' relationships with the Company, RMR Inc. or RMR LLC and the other companies to which RMR LLC or its subsidiaries provide management services. The Board has concluded that none of these three Trustees possessed or currently possesses any relationship that could impair his or her judgment in connection with his or her duties and responsibilities as a Trustee or that could otherwise be a direct or indirect material relationship under applicable Nasdaq and SEC standards.

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The Board has an Audit Committee, Compensation Committee and Nominating and Governance Committee. The Audit Committee, Compensation Committee and Nominating and Governance Committee have each adopted a written charter, which is available on the Company's website, www.snhreit.com, by clicking on "Investors" and then clicking on "Governance." Shareholders may also request copies free of charge by writing to Investor Relations, Senior Housing Properties Trust, Two Newton Place, 255 Washington Street, Suite 300, Newton, Massachusetts 02458.

Our Audit Committee, Compensation Committee and Nominating and Governance Committee are comprised entirely of Independent Trustees, and an Independent Trustee serves as Chair of each committee. The Director of Internal Audit, with the assistance of Company management, proposes the agenda for committee meetings under the oversight and direction of the Committee Chairs. Additionally, the charter of each of our Audit Committee, Compensation Committee and Nominating and Governance Committee provides that the committee may form and delegate authority to subcommittees of one or more members when appropriate. Subcommittees are subject to the provisions of the applicable committee's charter. Additional information about the committees is provided below.

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The Board is elected by shareholders to oversee the Company's business and long term strategy. As part of fulfilling its responsibilities, the Board oversees the safeguarding of the assets of the Company, the maintenance of appropriate financial and other internal controls and the Company's compliance with applicable laws and regulations. Inherent in these responsibilities is the Board's understanding and oversight of the various risks facing the Company. The Board considers that risks should not be viewed in isolation and should be considered in virtually every business decision and as part of the Company's business strategy.

The Board oversees risk as part of its general oversight of the Company. Oversight of risk is addressed as part of various Board and Board committee activities and through regular and special Board and Board committee meetings. The actual day to day business of the Company is conducted by RMR LLC, and RMR LLC and the Company's officers and Director of Internal Audit are responsible to incorporate risk management in their activities. The Company's Director of Internal Audit provides the Company advice and assistance with the Company's risk management function.

In discharging their oversight responsibilities, the Board and Board committees review regularly a wide range of reports provided to them by RMR LLC and other service providers, including:

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reports on market and industry conditions;



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operating and regulatory compliance reports;



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financial reports;



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reports on risk management activities;



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regulatory and legislative updates that may impact the Company;



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reports on the security of the Company's information technology processes and the Company's data; and



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legal proceedings updates and reports on other business related matters.

The Board and Board committees discuss these matters among themselves and with representatives of RMR LLC, officers of the Company, the Director of Internal Audit, counsel and the Company's independent auditors.

The Audit Committee takes a leading role in helping the Board fulfill its responsibilities for oversight of the Company's financial reporting, internal audit function, risk management and the Company's compliance with legal and regulatory requirements. The Audit Committee meets at least quarterly and reports its findings to the Board. The Board and Audit Committee review periodic reports from the Company's independent auditors regarding potential risks, including risks related to the Company's internal control over financial reporting. The Audit Committee also reviews annually, approves and oversees an internal audit plan developed by the Company's Director of Internal Audit with the goal of helping the Company systematically evaluate the effectiveness of its risk management, control and governance processes. The Audit Committee also meets periodically with the Company's Director of Internal Audit to review the results of the Company's internal audits, and directs or recommends to the Board actions or changes it determines appropriate to enhance or improve the effectiveness of the Company's risk management.

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The Compensation Committee evaluates the performance of the Company's Director of Internal Audit and RMR LLC's performance under the Company's business and property management agreements, including any perceived risks created by compensation arrangements. Also, the Compensation Committee and the Board consider that the Company has a share award program that requires share awards to executive officers to vest over a period of years. The Company believes that the use of share awards vesting over time rather than stock options mitigates the incentives for the Company's management to undertake undue risks and encourages management to make longer term and appropriately risk balanced decisions.

It is not possible to identify all of the risks that may affect the Company or to develop processes and controls to eliminate all risks and their possible effects, and processes and controls employed to address risks may be limited in their effectiveness. Moreover, it is necessary for the Company to bear certain risks to achieve its objectives. As a result of the foregoing and other factors, the Company's ability to manage risk is subject to substantial limitations.

To learn more about the risks facing the Company, you can review the matters discussed in Part I, "Item 1A. Risk Factors" and "Warning Concerning Forward Looking Statements" in our Annual Report. The risks described in the Annual Report are not the only risks facing the Company. Additional risks and uncertainties not currently known or that may currently be deemed to be immaterial also may materially adversely affect the Company's business, financial condition or results of operations in future periods.

Shareholders may effectively communicate a point of view to the Board in a number of ways, including:

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recommending candidates for election to the Board;



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participating in the advisory vote to approve executive compensation;



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directing communications to individual Trustees or the entire Board; and



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attending the annual meeting of shareholders.

The Board has established a process to facilitate communication by shareholders and other interested parties with Trustees. Communications should be addressed to Trustees in care of the Secretary, Senior Housing Properties Trust, Two Newton Place, 255 Washington Street, Suite 300, Newton, Massachusetts 02458 or by email to secretary@snhreit.com.

The Company has adopted the Code to, among other things, provide guidance to our Trustees and officers and RMR LLC, its officers and employees and its parent's and subsidiaries' directors, officers and employees to ensure compliance with applicable laws and regulations.

The Company's shareholders, Trustees, executive officers and persons involved in the Company's business can ask questions about the Code and other ethics and compliance issues, or report potential violations as follows: by writing to the Director of Internal Audit at Senior Housing Properties Trust, Two Newton Place, 255 Washington Street, Suite 300, Newton, Massachusetts 02458; by calling toll free (866) 511-5038; by emailing Internal.Audit@snhreit.com; or by filling out a report by visiting the Company's website, www.snhreit.com, clicking "Investors," clicking "Governance" and then clicking "Governance Hotline." We intend to satisfy the requirements under Item 5.05 of Form 8-K regarding disclosure of amendments to, or waivers from, provisions of our Code that apply to the principal executive officer, principal financial officer or controller, or persons performing similar functions, by posting such information on our website.

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Trustee Share Ownership Policy.    All Trustees receive compensation in Common Shares to align the interests of Trustees with those of the Company's shareholders. The Company's Governance Guidelines codify our expectation that, subject to certain exemptions, each Trustee retain at least 20,000 Common Shares by the later of: (i) the date of the 2019 annual meeting of shareholders of the Company and (ii) five years from the annual meeting of shareholders of the Company at which the Trustee was initially elected or, if earlier, the first annual meeting of shareholders of the Company following the initial appointment of the Trustee to the Board.

Trustee Resignation Policy.    The Governance Guidelines provide that 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. In such circumstance, the Nominating and Governance Committee will make a recommendation to the Board on whether to accept or reject the resignation offer, or whether other action should be taken. The Board will act on the resignation offer taking into account the recommendation of the Nominating and Governance Committee and make its decision within 90 days following the certification of the election results.

Pursuant to the Company's insider trading policy, Trustees and executive officers are required to obtain pre-approval from at least two designated individuals before trading or agreeing to trade in, including by entering into a share trading plan such as a 10b5-1 trading plan, with respect to any Company security, except for regular reinvestments in the Company's securities made pursuant to a dividend reinvestment plan.

The Company's insider trading policy generally prohibits (i) the Company's Trustees and officers, (ii) the trustees and officers of the Company's subsidiaries, (iii) RMR Inc. and its directors and officers and (iv) RMR LLC and its officers and employees, to the extent they are involved in RMR LLC's services to the Company, from, directly or indirectly through family members or others, purchasing or selling Common Shares or the Company's other equity or debt securities while in possession of material, non-public information concerning the Company. Similar prohibitions also apply to trading in the securities of RMR Inc. and the other public companies to which RMR LLC provides management services on the basis of material, non-public information learned in the course of performing services for those companies.

The Company's business strategy incorporates and values environmental sustainability principles. The Company seeks to operate its properties in a manner that improves the environmental efficiency of their operations. The Company regularly considers ways to improve the Company's internal culture and the communities in which it operates. The Company's environmental sustainability and community engagement strategies are primarily implemented by its manager, RMR LLC, and focus on a complementary set of objectives, including the following:

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Responsible Investment: During the acquisition of properties, RMR LLC assesses, among other things, environmental sustainability opportunities and climate related risks as part of the due diligence process. The Company regularly seeks to invest in sustainability practices that improves environmental performance and enhances asset value.



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Environmental Stewardship: The Company, through RMR LLC, seeks to improve the environmental footprint of its properties, including by reducing energy consumption and water usage at the Company's properties, especially when doing so may reduce operating costs and improve the properties' competitive positions.

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Corporate Citizenship: The Company seeks to be a responsible corporate citizen and to strengthen the communities in which it owns properties. The Company has no employees but the Company's manager, RMR LLC, regularly encourages its employees to engage in a variety of charitable and community programs, including participation in a company wide service day and a matching charitable giving program.

To learn more about the Company's and RMR LLC's sustainability initiatives, visit www.rmrgroup.com/corporate-sustainability.

See the "Compensation Discussion and Analysis" beginning on page 50 for a detailed discussion of the Company's executive compensation program.

Trustee Nominations and Shareholder Proposals for the 2019 Annual Meeting of Shareholders: In order for a shareholder to propose a nominee for election to the Board or propose business outside of Rule 14a-8 under the Exchange Act at the 2019 annual meeting of shareholders, the shareholder must comply with the advance notice and other requirements set forth in our Declaration of Trust and Bylaws, which include, among other things, requirements as to the shareholder's timely delivery of advance notice, continuous requisite ownership of Common Shares, holding of a share certificate for such shares at the time of the advance notice and submission of specified information.

Deadline to Submit Nominations and Proposals for the 2019 Annual Meeting of Shareholders under our Bylaws: To be timely, shareholder nominations and proposals intended to be made outside of Rule 14a-8 under the Exchange Act at the 2019 annual meeting of shareholders must be received by the Company's Secretary at the Company's principal executive offices, in accordance with the requirements of our Declaration of Trust and Bylaws, not later than 5:00 p.m., Eastern time, on December 4, 2018 and not earlier than November 4, 2018; provided, that, if the date of the 2019 annual meeting of shareholders is more than 30 days earlier or later than May 22, 2019, then a shareholder's notice must be so delivered not later than 5:00 p.m., Eastern time, on the tenth day following the earlier of the day on which (i) notice of the date of the 2019 annual meeting of shareholders is mailed or otherwise made available or (ii) public announcement of the date of the 2019 annual meeting of shareholders is first made by the Company.

Deadline to Submit Proposals for the 2019 Annual Meeting of Shareholders for Purposes of Rule 14a-8: Shareholder proposals pursuant to Rule 14a-8 under the Exchange Act must be received at the Company's principal executive offices on or before December 4, 2018 in order to be eligible to be included in the proxy statement for the 2019 annual meeting of shareholders; provided, that, if the date of the 2019 annual meeting of shareholders is more than 30 days before or after May 22, 2019, such a proposal must be submitted within a reasonable time before the Company begins to print its proxy materials. Under Rule 14a-8, the Company is not required to include shareholder proposals in its proxy materials in certain circumstances or if conditions specified in the rule are not met.

The foregoing description of the requirements for a shareholder to propose a nomination for election to the Board at an annual meeting of shareholders or other business for consideration at an annual meeting of shareholders is only a summary and is not a complete listing of all requirements. Copies of our Declaration of Trust and Bylaws, including the requirements for shareholder nominations and other proposals, may be obtained by writing to the Company's Secretary at Senior Housing Properties Trust, Two Newton Place, 255 Washington Street, Suite 300, Newton, Massachusetts 02458, or from the SEC's website, www.sec.gov. Any shareholder considering making a nomination or other proposal should carefully review and comply with those provisions.

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The descriptions of agreements in this "Related Person Transactions" section do not purport to be complete and are subject to, and qualified in their entirety by, reference to the actual agreements, copies of certain of which are filed as exhibits to the Annual Report.

A "related person transaction" is a transaction, arrangement or relationship (or any series of similar transactions, arrangements or relationships) in which (i) the Company was, is or will be a participant, (ii) the amount involved exceeds $120,000 and (iii) any related person had, has or will have a direct or indirect material interest.

A "related person" means any person who is, or at any time since January 1, 2017 was:

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a Trustee, a nominee for Trustee or an executive officer of the Company;



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known to the Company to be the beneficial owner of more than 5.0% of the outstanding Common Shares when a transaction in which such person had a direct or indirect material interest occurred or existed;



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an immediate family member of any of the persons referenced in the preceding two bullets, which means any child, stepchild, parent, stepparent, spouse, sibling, mother-in-law, father-in-law, son-in-law, daughter-in-law, brother-in-law or sister-in-law of any of the persons referenced in the preceding two bullets, and any person (other than a tenant or employee) sharing the household of any of the persons referenced in the preceding two bullets; or



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a firm, corporation or other entity in which any of the foregoing persons is a partner or principal or in a similar position or in which such person has a 10.0% or greater beneficial ownership interest.

The Company has adopted written Governance Guidelines that describe the consideration and approval of related person transactions. Under these Governance Guidelines, the Company may not enter a transaction in which any Trustee or executive officer, any member of the immediate family of any Trustee or executive officer or other related person, has or will have a direct or indirect material interest unless that transaction has been disclosed or made known to the Board and the Board reviews and approves or ratifies the transaction by the affirmative vote of a majority of the disinterested Trustees, even if the disinterested Trustees constitute less than a quorum. If there are no disinterested Trustees, the transaction must be reviewed, authorized and approved or ratified by both (i) the affirmative vote of a majority of the Board and (ii) the affirmative vote of a majority of the Independent Trustees. In determining whether to approve or ratify a transaction, the Board, or disinterested Trustees or Independent Trustees, as the case may be, also act in accordance with any applicable provisions of the Company's Declaration of Trust and Bylaws and consider all of the relevant facts and circumstances and approve only those transactions that they determine are fair and reasonable to the Company. All related person transactions described below were reviewed and approved or ratified by a majority of the disinterested Trustees or otherwise in accordance with the Company's policies, Declaration of Trust and Bylaws, each as described above. In the case of transactions with the Company by employees of RMR Inc. and its subsidiaries who are subject to the Code but who are not Trustees or executive officers of the Company, the employee must seek approval from an executive officer who has no interest in the matter for which approval is being requested. Copies of the Company's Governance Guidelines and the Code are available on the Company's website, www.snhreit.com.

Certain Related Person Transactions

Relationship with FVE. FVE was the Company's 100% owned subsidiary until the Company distributed its common shares to the Company's shareholders in 2001. The Company is currently one of FVE's largest stockholders, owning, as of December 31, 2017, 4,235,000 FVE common shares, or 8.5% of FVE's outstanding common shares. FVE is the Company's largest tenant and the manager of the Company's managed senior living communities.

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RMR LLC provides management services to both the Company and FVE. RMR Inc., the managing member of RMR LLC, is controlled by ABP Trust, which is controlled by one of the Company's Managing Trustees, Adam D. Portnoy. As of December 31, 2017, Adam D. Portnoy and Barry M. Portnoy, the Company's then Managing Trustees, beneficially owned an aggregate of 18,382,121 FVE common shares, or 36.7% of FVE's outstanding common shares. Adam D. Portnoy also serves as a managing director of FVE, and Barry M. Portnoy also served as a managing director of FVE until his death on February 25, 2018. FVE's president and chief executive officer, chief financial officer and treasurer and senior vice president and general counsel are officers and employees of RMR LLC, and FVE's chief financial officer and treasurer was formerly the Company's Chief Financial Officer and Treasurer from 2007 through 2015.

In order to effect the distribution of FVE common shares to the Company's shareholders in 2001 and to govern the Company's relations with FVE thereafter, FVE entered agreements with the Company and others, including RMR LLC. Since then, the Company has entered various leases, management agreements and other agreements with FVE that include provisions that confirm and modify these undertakings. Among other things, these agreements provide that:

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so long as the Company remains a REIT, FVE may not waive the share ownership restrictions in its charter that prohibit any person or group from acquiring more than 9.8% (in value or number of shares, whichever is more restrictive) of the outstanding shares of any class of FVE stock without the Company's consent;



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so long as FVE is the Company's tenant or manager, FVE will not permit nor take any action that, in the Company's reasonable judgment, might jeopardize the Company's qualification for taxation as a REIT;



•

the Company has the right to terminate the leases and management agreements it has with FVE upon the acquisition by a person or group of more than 9.8% of FVE's voting stock or other change in control events, as defined therein, affecting FVE, including the adoption of any shareholder proposal (other than a precatory proposal) or the election to FVE's board of directors of any individual, if such proposal or individual was not approved, nominated or appointed, as the case may be, by a majority of FVE's directors in office immediately prior to the making of such proposal or the nomination or appointment of such individual; and



•

so long as FVE is a tenant of the Company or manager for the Company or has a business management agreement with RMR LLC, FVE will not acquire or finance any real estate of a type then owned or financed by the Company or any other company managed by RMR LLC without first giving the Company or such company managed by RMR LLC, as applicable, the opportunity to acquire or finance that real estate.

The Company's Senior Living Communities Leased by FVE. The Company is FVE's largest landlord and FVE is the Company's largest tenant. As of December 31, 2017, the Company leased 185 senior living communities to FVE pursuant to the following five leases with FVE:

•

Lease No. 1, which expires in 2024 and includes 83 independent living communities, assisted living communities and skilled nursing facilities ("SNFs").



•

Lease No. 2, which expires in 2026 and includes 47 independent living communities, assisted living communities and SNFs.



•

Lease No. 3, which expires in 2028 and includes 17 independent living communities and assisted living communities.



•

Lease No. 4, which expires in 2032 and includes 29 independent living communities, assisted living communities and SNFs.



•

Lease No. 5, which expires in 2028 and includes nine assisted living communities.

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Under the Company's leases with FVE, FVE pays the Company annual rent plus percentage rent equal to 4.0% of the increase in gross revenues at certain of the Company's senior living communities over base year gross revenues as specified in the applicable lease. FVE's obligation to pay percentage rent under Lease No. 5 commenced in 2018. The Company determines percentage rent due under these leases annually and recognize it at year end when all contingencies are met. The Company recognized total rental income from FVE of approximately $210.5 million (including percentage rent of approximately $5.5 million) for the year ended December 31, 2017. As of December 31, 2017, FVE's total annual rent payable to the Company was approximately $206.3 million, excluding percentage rent. Under the Company's leases with FVE, FVE has the option to extend the lease term for two consecutive 10 or 15 year terms. The Company has the right, in connection with a financing or other capital raising transaction, to reassign one or more of the communities covered by Lease No. 3 or Lease No. 5 to another of our long term lease agreements with FVE.

The Company's leases with FVE are "triple net" leases, which generally require FVE to pay rent and all property operating expenses, to indemnify the Company from liability which may arise by reason of the Company's ownership of the properties, to maintain the properties at FVE's expense, to remove and dispose of hazardous substances on the properties in compliance with applicable law and to maintain insurance on the properties for FVE's and the Company's benefit. In the event of any damage, or immaterial condemnation, of a leased property, FVE is generally required to rebuild with insurance or condemnation proceeds or, if such proceeds are insufficient, other amounts made available by the Company, if any, but if other amounts are made available by the Company, the rent will be increased accordingly. In the event of any material or total condemnation of a leased property, the lease will terminate with respect to that leased property, in which event the Company will be entitled to the condemnation proceeds and the rent will be reduced accordingly. In the event of any material or total destruction of a leased property, FVE may terminate the lease with respect to that leased property, in which event FVE will be required to pay the Company any shortfall in the amount of proceeds the Company receives from insurance compared to the replacement cost of that leased property and the rent will be reduced accordingly.

Under the Company's leases with FVE, FVE may request that the Company purchase certain improvements to the leased communities in return for rent increases in accordance with a formula specified in the applicable lease; however, the Company is not obligated to purchase such improvements and FVE is not obligated to sell them to the Company. During the year ended December 31, 2017, the Company purchased approximately $39.8 million of such improvements and FVE's annual minimum rent payable to the Company increased by approximately $3.2 million, in accordance with the terms of the applicable leases.

In August 2017, the Company acquired a land parcel from FVE adjacent to a senior living community located in Delaware that the Company leases to FVE for approximately $750,000, excluding closing costs. This land parcel was added to the applicable lease and FVE's annual minimum rent payable to the Company increased by approximately $33,000 in accordance with the terms of that lease.

During the quarter ended June 30, 2017, the Company and FVE agreed to amend the applicable lease for certain construction, expansion and development projects at two senior living communities the Company owns and leases to FVE. If and when FVE requests that the Company purchase improvements related to these specific projects from them, FVE's annual rent payable to the Company will increase by an amount equal to the interest rate then applicable to the Company's borrowings under its revolving credit facility plus 2.0% per annum of the amount the Company purchased. This amount of increased rent will apply until 12 months after a certificate of occupancy is issued with respect to the project; thereafter, FVE's annual rent payable to the Company will be revised to equal the amount otherwise determined pursuant to the capital improvement formula specified in the applicable lease.

The Company's Senior Living Communities Managed by FVE. As of December 31, 2017, the Company owned 70 senior living communities that were managed by FVE. The Company leases its senior living communities that are managed by FVE and include assisted living units or SNF units to the Company's

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taxable REIT subsidiaries ("TRSs"), and FVE manages these communities pursuant to long term management agreements.

The Company and FVE have pooling agreements that combine most of the Company's AL Management Agreements. The pooling agreements combine various calculations of revenues and expenses from the operations of the applicable communities covered by such agreements. The Company's AL Management Agreements and pooling agreements generally provide that FVE receives:

•

a management fee equal to either 3.0% or 5.0% of the gross revenues realized at the applicable communities,



•

reimbursement for its direct costs and expenses related to such communities,



•

an annual incentive fee equal to either 35.0% or 20.0% of the annual net operating income of such communities remaining after the Company realizes an annual minimum return equal to either 8.0% or 7.0% of its invested capital, or, in the case of certain of the communities, a specified amount plus 7.0% of the Company's invested capital since December 31, 2015, and



•

a fee for its management of capital expenditure projects equal to 3.0% of amounts funded by the Company.

The Company's management agreement with FVE for the part of the senior living community located in New York that is not subject to the requirements of New York healthcare licensing laws, as described elsewhere herein, and the management agreement for one of the Company's assisted living communities located in California, are not currently included in any of the Company's pooling agreements with FVE.

The Company also has a pooling agreement with FVE that combines the Company's management agreements with FVE for senior living communities consisting only of independent living units.

The Company's management agreements with FVE generally expire between 2030 and 2041, and are subject to automatic renewal for two consecutive 15 year terms, unless earlier terminated or timely notice of nonrenewal is delivered. These management agreements also generally provide that the Company, and in some cases FVE, each have the option to terminate the agreements upon the acquisition by a person or group of more than 9.8% of the other's voting stock and upon certain change in control events affecting the other party, as defined in the applicable agreements, including the adoption of any shareholder proposal (other than a precatory proposal) with respect to the other party, or the election to the board of directors or trustees, as applicable, of the other party of any individual, if such proposal or individual was not approved, nominated or appointed, as the case may be, by a majority of the other party's board of directors or board of trustees, as applicable, in office immediately prior to the making of such proposal or the nomination or appointment of such individual.

During the quarter ended June 30, 2017, the Company and FVE agreed to amend the applicable management and pooling agreements for a construction, expansion and development project at a senior living community that the Company owns and that is managed by FVE. The Company's minimum return on invested capital for this specific project will increase by an amount equal to the interest rate then applicable to the Company's borrowings under its revolving credit facility plus 2.0% per annum. This amount of increased minimum return will apply until 12 months after a certificate of occupancy is issued with respect to the project; thereafter, the amount of annual minimum return on invested capital will be revised to equal the amount otherwise determined pursuant to the applicable management and pooling agreements. The Company and FVE also agreed that the commencement of the measurement period for determining whether the specified annual minimum return under the applicable management and pooling agreements has been achieved will be deferred until 12 months after a certificate of occupancy is issued with respect to the project.

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Transaction Agreement with FVE. In November 2017, the Company entered a transaction agreement with FVE pursuant to which the Company agreed to acquire six senior living communities from FVE. Pursuant to this transaction agreement, the Company also agreed that, as the Company acquires these communities, (i) the Company and FVE would enter new management agreements for FVE to manage these senior living communities for us and (ii) the new management agreements would be combined pursuant to two new pooling agreements to be entered between the Company and FVE. In December 2017, January 2018 and February 2018, the Company acquired, and FVE began managing for the Company's account, two of these senior living communities located in Alabama and Indiana, one of these senior living communities located in Tennessee and one of these senior living communities located in Arizona, respectively and, in connection with those acquisitions, the Company entered management agreements with FVE for each of these senior living communities and two new pooling agreements with FVE. Pursuant to the terms of the management and pooling agreements for five of these senior living communities, the Company will pay FVE a management fee equal to 5.0% of the gross revenues realized at these communities plus reimbursement for FVE's direct costs and expenses related to its operation of these communities, as well as an annual incentive fee equal to 20.0% of the annual net operating income of such communities remaining after the Company realizes an annual minimum return equal to 7.0% of its invested capital for these senior living communities. The terms of the management and pooling agreement for one of these senior living communities that is subject to an ongoing construction, expansion and development project are substantially the same as the terms of the management and pooling agreements for the other five senior living communities, except that the Company's annual minimum return on invested capital related to the ongoing construction and development project at this community will be an amount equal to the interest rate then applicable to borrowings under the Company's revolving credit facility plus 2.0% per annum. This amount of minimum return will apply until the earlier of 12 months after a certificate of occupancy is issued with respect to the project and the third anniversary of the Company's acquisition of this community; thereafter, the amount of annual minimum return on invested capital related to this project will be 7.0% of the Company's invested capital. Also pursuant to the terms of the management and pooling agreements for these senior living communities, the Company will pay FVE a fee for its management of capital expenditure projects at these senior living communities equal to 3.0% of amounts funded by the Company. The terms of these management and pooling agreements will expire in 2041 and will be subject to automatic renewals for two 15 year periods thereafter, unless earlier terminated or timely notices of nonrenewal are delivered. The remaining acquisitions under the transaction agreement are subject to conditions, including the Company's assumption of certain applicable mortgage debt and receipt of any applicable regulatory approvals. The conditions to these acquisitions may not be met and some or all of these acquisitions may not be completed, may be delayed or the terms of these acquisitions or the management and pooling agreements for these communities may change.

Also in November 2017, the Company amended its preexisting pooling agreements with FVE, among other things, to provide that, with respect to its right to terminate all of the management agreements covered by a preexisting pooling agreement if the Company does not receive its annual minimum return under such agreement in each of three consecutive years, the commencement year for the measurement period for determining whether the specified annual minimum return under the applicable pooling agreement has been achieved will be 2017.

The Company incurred management fees of approximately $14.1 million for the year ended December 31, 2017 with respect to the communities FVE manages for the Company. In addition to management services to the Company, FVE also provides certain other services to residents at some of the senior living communities it manages for the Company, such as rehabilitation services. At senior living communities FVE manages for the Company where FVE provides rehabilitation services on an outpatient basis, the residents, third party payers or government programs pay FVE for those rehabilitation services. At senior living communities FVE manages for the Company where FVE provides both inpatient and outpatient rehabilitation services, the Company generally pays FVE for these services and charges for these services are included in amounts charged to residents, third party payers or government programs. The Company incurred fees of $7.5 million for the year ended December 31, 2017 with respect to rehabilitation services FVE provided at senior living communities it manages for the Company that are payable by the Company.

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D&R Yonkers LLC. The Company owns a senior living community in New York with 310 living units, a part of which is managed by FVE pursuant to a long term management agreement with the Company with respect to the senior living units at this community that are not subject to the requirements of New York healthcare licensing laws. The terms of this management agreement are substantially consistent with the terms of the Company's other management agreements with FVE for communities that include assisted living units, and provide for a management fee payable to FVE equal to 5.0% of the gross revenues realized, except there is no incentive fee payable by the Company to FVE. This management agreement expires on December 31, 2031.

In order to accommodate certain requirements of New York healthcare licensing laws, one of the Company's TRSs subleases the part of this community that is subject to the requirements of those laws to D&R Yonkers LLC, an entity which is owned by the Company's President and Chief Operating Officer and FVE's chief financial officer and treasurer. FVE manages this part of the community pursuant to a long term management agreement with D&R Yonkers LLC under which FVE earns a management fee equal to 3.0% of the gross revenues realized at that part of the community and no incentive fee is payable to FVE. D&R Yonkers LLC's management agreement with FVE expires on August 31, 2022, and is subject to renewal for eight consecutive five year terms, unless earlier terminated or timely notice of nonrenewal is delivered. The Company has entered into an indemnification agreement with the owners of D&R Yonkers LLC, pursuant to which the Company has agreed to indemnify them for costs, losses and expenses they may sustain by reason of being a member, director or officer of D&R Yonkers LLC or in connection with any costs, losses or expenses under the Company's TRS's sublease with D&R Yonkers LLC or the management agreement between D&R Yonkers LLC and FVE.

Relationships with RMR LLC and Others Related to It. The Company has relationships and historical and continuing transactions with RMR LLC, RMR Inc. and others related to them. RMR LLC is a majority owned subsidiary of RMR Inc. Adam D. Portnoy, one of our Managing Trustees, is the sole trustee of, and owns beneficial interest in, ABP Trust, the controlling shareholder of RMR Inc. A former Managing Trustee of the Company, Barry M. Portnoy, served as a trustee of, and owned a majority of the beneficial interest in, ABP Trust until his death on February 25, 2018. Adam D. Portnoy is a managing director and an officer of RMR Inc. and is an officer of ABP Trust and RMR LLC. Adam D. Portnoy, as the sole trustee of ABP Trust, beneficially owns all the class A membership units of RMR LLC not owned by RMR Inc. Barry M. Portnoy served as a Managing Trustee of the Company and as a managing director and an officer of RMR Inc. and an officer of RMR LLC until his death on February 25, 2018. Jennifer B. Clark, the other current Managing Trustee of the Company, also serves as a managing director and an officer of RMR Inc. and an officer of RMR LLC. Each of the Company's executive officers is also an officer and employee of RMR LLC. Adam D. Portnoy serves, and until his death Barry M. Portnoy served, as a managing trustee or managing director of all of the public companies to which RMR LLC or its subsidiaries provide management services. The Company's Independent Trustees also serve as independent trustees or independent directors of other public companies to which RMR LLC or its subsidiaries provide management services. In addition, officers of RMR LLC and RMR Inc. serve as the Company's officers and officers of other companies to which RMR LLC or its subsidiaries provide management services.

On March 29, 2018, David J. Hegarty announced his decision to resign from his position as an executive vice president of RMR LLC and as the Company's President and Chief Operating Officer effective April 30, 2018. In connection with his retirement, RMR LLC entered into a retirement agreement with Mr. Hegarty on March 29, 2018. Pursuant to his retirement agreement, Mr. Hegarty will remain an employee of RMR LLC until September 30, 2018 or such earlier date as he may elect. In connection with his retirement, the Compensation Committee fully accelerated the vesting of all of the Common Shares previously awarded to Mr. Hegarty effective upon the date of his retirement from RMR LLC that remain unvested as of such date, subject to conditions. Pursuant to his retirement agreement, Mr. Hegarty agreed that, as long as he owns shares in the Company, he will vote those shares at shareholders' meetings in favor of nominees for Trustees and proposals recommended by the Board. Mr. Hegarty made a similar agreement for the benefit of RMR Inc. and the other public companies to which RMR LLC provides management services.

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The Company has no employees. The personnel and various services the Company requires to operate its business are provided to it by RMR LLC. The Company has two agreements with RMR LLC to provide management services to the Company: (i) a business management agreement, which relates to the Company's business generally, and (ii) a property management agreement, which relates to the property level operations of the Company's properties leased to medical providers, medical related businesses, clinics and biotech laboratory tenants ("MOBs"), both of which are described below, see "—Management Agreements With RMR LLC."

Interest in RMR Inc. The Company currently holds 2,637,408 shares of class A common stock of RMR Inc., the parent and managing member of RMR LLC. The Company and three Other RMR Managed REITs, HPT, GOV and SIR, acquired shares of class A common stock of RMR Inc. in a transaction completed on June 5, 2015 (the "Up-C Transaction"). Through their ownership of class A common stock of RMR Inc., class B-1 common stock of RMR Inc., class B-2 common stock of RMR Inc. and class A membership units of RMR LLC, as of February 1, 2018, Adam D. Portnoy and Barry M. Portnoy, in aggregate held, directly and indirectly (including as trustees of ABP Trust), a 51.9% economic interest in RMR LLC and controlled 91.4% of the voting power of outstanding capital stock of RMR Inc. As part of the Up-C Transaction, on June 5, 2015, the Company entered into a registration rights agreement with RMR Inc. covering the class A common stock of RMR Inc. that the Company received in the Up-C Transaction, pursuant to which the Company received demand and piggyback registration rights, subject to certain limitations, and the Company entered into a lock up and registration rights agreement with ABP Trust and Adam D. Portnoy and Barry M. Portnoy pursuant to which ABP Trust and Adam D. Portnoy and Barry M. Portnoy agreed not to transfer the 2,345,000 Common Shares that ABP Trust received in the Up-C Transaction for a 10 year period ending on June 5, 2025, and the Company granted them certain registration rights, subject to certain exceptions.

Management Agreements with RMR LLC. The Company's management agreements with RMR LLC provide for an annual base management fee, an annual incentive management fee and property management and construction supervision fees, payable in cash, among other terms:

•

Base Management Fee. The annual base management fee payable to RMR LLC by the Company for each applicable period is equal to the lesser of:



◦

the sum of (a) 0.5% of the daily weighted average of the aggregate book value of the Company's real estate assets owned by the Company or its subsidiaries as of October 12, 1999 (the "Transferred Assets"), plus (b) 0.7% of the average aggregate historical cost of the Company's real estate investments excluding the Transferred Assets up to $250.0 million, plus (c) 0.5% of the average aggregate historical cost of the Company's real estate investments excluding the Transferred Assets exceeding $250.0 million; and



◦

the sum of (a) 0.7% of the average closing price per share of the Common Shares on the stock exchange on which such Common Shares are principally traded during such period, multiplied by the average number of the Common Shares outstanding during such period, plus the daily weighted average of the aggregate liquidation preference of each class of the Company's preferred shares outstanding during such period, plus the daily weighted average of the aggregate principal amount of the Company's consolidated indebtedness during such period (together, the "Company's Average Market Capitalization"), up to $250.0 million, plus (b) 0.5% of the Company's Average Market Capitalization exceeding $250.0 million.

The average aggregate historical cost of the Company's real estate investments includes its consolidated assets invested, directly or indirectly, in equity interests in or loans secured by real estate and personal property owned in connection with such real estate (including acquisition related costs and costs which may be allocated to intangibles or are unallocated), all before reserves for depreciation, amortization, impairment charges or bad debts or other similar non cash reserves.

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•

Incentive Management Fee. The incentive management fee which may be earned by RMR LLC for an annual period is calculated as follows:



◦

An amount, subject to a cap, based on the value of the outstanding Common Shares, equal to 12.0% of the product of:



•

the Company's equity market capitalization on the last trading day of the year immediately prior to the relevant three year measurement period, and



•

the amount (expressed as a percentage) by which the total return per share, as defined in the business management agreement and further described below, of the holders of Common Shares (i.e., share price appreciation plus dividends) exceeds the total shareholder return of the SNL U.S. REIT Healthcare Index, or the benchmark return per share, for the relevant measurement period.

For purposes of the total return per share of the holders of Common Shares, share price appreciation for a measurement period is determined by subtracting (1) the closing price of our common shares on the Nasdaq on the last trading day of the year immediately before the first year of the measurement period from (2) the average closing price of our common shares on the 10 consecutive trading days having the highest average closing prices during the final 30 trading days in the last year of the measurement period.

◦

The calculation of the incentive management fee (including the determinations of our equity market capitalization and the total return per share of holders of Common Shares) is subject to adjustments if additional Common Shares are issued during the measurement period.



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No incentive management fee is payable by the Company unless its total return per share during the measurement period is positive.



◦

The measurement periods are three year periods ending with the year for which the incentive management fee is being calculated.



◦

If the Company's total return per share exceeds 12.0% per year in any measurement period, the benchmark return per share is adjusted to be the lesser of the total shareholder return of the SNL U.S. REIT Healthcare Index for such measurement period and 12.0% per year, or the adjusted benchmark return per share. In instances where the adjusted benchmark return per share applies, the incentive management fee will be reduced if the Company's total return per share is between 200 basis points and 500 basis points below the SNL U.S. REIT Healthcare Index by a low return factor, as defined in the business management agreement, and there will be no incentive management fee paid if, in these instances, the Company's total return per share is more than 500 basis points below the SNL U.S. REIT Healthcare Index.



◦

The incentive management fee is subject to a cap. The cap is equal to the value of the number of Common Shares which would, after issuance, represent 1.5% of Common Shares then outstanding multiplied by the average closing price of Common Shares during the 10 consecutive trading days having the highest average closing prices during the final 30 trading days of the relevant measurement period.



◦

Incentive management fees the Company paid to RMR LLC for any period may be subject to "clawback" if the Company's financial statements for that period are restated due to material non-compliance with any financial reporting requirements under the securities laws as a result of the bad faith, fraud, willful misconduct or gross negligence of RMR LLC and the amount of the incentive management fee the Company paid was greater than the amount the Company would have paid based on the restated financial statements.

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44    SENIOR HOUSING PROPERTIES TRUST     2018 Proxy Statement

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Property Management and Construction Supervision Fees. The property management fees payable to RMR LLC by the Company for each applicable period are equal to 3.0% of gross collected rents and the construction supervision fees payable to RMR LLC by the Company for each applicable period are equal to 5.0% of construction costs.

Pursuant to the Company's business management agreement with RMR LLC, the Company recognized business management fees of approximately $38.6 million for the year ended December 31, 2017, which amount reflects a reduction of approximately $3.0 million for the amortization of the liability the Company recorded in accordance with generally accepted accounting principles in connection with the Up-C Transaction.

Pursuant to the Company's business management agreement, in January 2018, the Company paid RMR LLC an incentive management fee of $55.7 million for the year ended December 31, 2017. In calculating the incentive management fee payable by the Company, the Company's total shareholder return per share¹ was adjusted in accordance with the business management agreement to reflect an aggregate increase in the number of Common Shares outstanding as a result of certain share issuances and repurchases by the Company in 2017.

Pursuant to the Company's property management agreement with RMR LLC, the Company recognized aggregate net property management and construction supervision fees of approximately $10.9 million for the year ended December 31, 2017, which amount reflects a reduction of approximately $798 million for the amortization of the liability the Company recorded in accordance with generally accepted accounting principles in connection with the Up-C Transaction.

•

Expense Reimbursement. The Company is generally responsible for all of its operating expenses, including certain expenses incurred by RMR LLC on its behalf. The Company's property level operating expenses are generally incorporated into rents charged to its tenants, including certain payroll and related costs incurred by RMR LLC. The Company reimbursed RMR LLC approximately $10.0 million for property management related expenses for the year ended December 31, 2017. The Company is generally not responsible for payment of RMR LLC's employment, office or administrative expenses incurred to provide management services to the Company, except for the employment and related expenses of RMR LLC's employees assigned to work exclusively or partly at the Company's properties, its share of the wages, benefits and other related costs of centralized accounting personnel and its share of RMR LLC's costs for providing the Company's internal audit function. The Audit Committee appoints the Company's Director of Internal Audit and the Compensation Committee approves the costs of the Company's internal audit function. The amounts recognized as expense for internal audit costs were approximately $0.3 million for the year ended December 31, 2017.



•

Term. The Company's management agreements with RMR LLC have terms that end on December 31, 2037, and automatically extend on December 31st of each year for an additional year, so that the terms of its management agreements thereafter end on the 20th anniversary of the date of the extension.



•

Termination Rights. The Company has the right to terminate one or both of its management agreements with RMR LLC: (i) at any time on 60 days' written notice for convenience, (ii) immediately on written notice for cause, as defined therein, (iii) on written notice given within

   

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¹

"Total shareholder return" for purposes of the incentive management fee calculation differs from "total shareholder return" presented in the performance graph in the Annual Report because "total shareholder return" for purposes of the incentive management fee calculation has been determined in accordance with the terms of the business management agreement and includes adjustments for Common Shares issued and repurchased during the period and other items whereas "total shareholder return" presented in the performance graph is determined in the same or similar manner as each index reflected in the performance graph and does not include such adjustments and other items.

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60 days after the end of an applicable calendar year for a performance reason, as defined therein, and (iv) by written notice during the 12 months following a change of control of RMR LLC, as defined therein. RMR LLC has the right to terminate the management agreements for good reason, as defined therein.

•

Termination Fee. If the Company terminates one or both of its management agreements with RMR LLC for convenience, or if RMR LLC terminates one or both of its management agreements for good reason, the Company has agreed to pay RMR LLC a termination fee in an amount equal to the sum of the present values of the monthly future fees, as defined therein, for the terminated management agreement(s) for the term that was remaining prior to such termination, which, depending on the time of termination would be between 19 and 20 years. If the Company terminates one or both of its management agreements with RMR LLC for a performance reason, the Company has agreed to pay RMR LLC the termination fee calculated as described above, but assuming a 10 year term was remaining prior to the termination. The Company is not required to pay any termination fee if it terminates its management agreements with RMR LLC for cause or as a result of a change of control of RMR LLC.



•

Transition Services. RMR LLC has agreed to provide certain transition services to the Company for 120 days following an applicable termination by the Company or notice of termination by RMR LLC, including cooperating with the Company and using commercially reasonable efforts to facilitate the orderly transfer of the management and real estate investment services provided under its business management agreement and to facilitate the orderly transfer of the management of the managed properties under its property management agreement, as applicable.



•

Vendors. Pursuant to the Company's management agreements with RMR LLC, RMR LLC may from time to time negotiate on the Company's behalf with certain third party vendors and suppliers for the procurement of goods and services to the Company. As part of this arrangement, the Company may enter agreements with RMR LLC and other companies to which RMR LLC provides management services for the purpose of obtaining more favorable terms from such vendors and suppliers.



•

Investment Opportunities. Under the Company's business management agreement with RMR LLC, the Company acknowledges that RMR LLC may engage in other activities or businesses and act as the manager to any other person or entity (including other REITs) even though such person or entity has investment policies and objectives similar to the Company's and the Company is not entitled to preferential treatment in receiving information, recommendations and other services from RMR LLC.

Share Awards to RMR LLC Employees. The Company has historically granted share awards to certain RMR LLC employees under the Company's equity compensation plans. During the year ended December 31, 2017, the Company granted annual share awards of 88,100 Common Shares to the Company's officers and to other employees of RMR LLC valued at approximately $1.7 million, based upon the closing price of the Common Shares on the Nasdaq on the date of grant. One fifth of those share awards vested on the grant date and one fifth vests on each of the next four anniversaries of the grant date. These share awards to such RMR LLC employees are in addition to the share awards granted to Adam D. Portnoy and Barry M. Portnoy, as the Company's then Managing Trustees, and the fees the Company paid to RMR LLC. In 2017, the Company purchased 16,654 Common Shares, at the closing price of the Common Shares on the Nasdaq on the date of purchase, from certain of the Company's officers and certain other employees of RMR LLC in satisfaction of tax withholding and payment obligations in connection with the vesting of awards of Common Shares.

On occasion, the Company has entered into arrangements with former employees of RMR LLC in connection with the termination of their employment with RMR LLC, providing for the acceleration of vesting of Common Share awards previously granted to them under the Company's equity compensation plans. Additionally, each of the Company's executive officers during 2017 received share awards of other

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46    SENIOR HOUSING PROPERTIES TRUST     2018 Proxy Statement

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companies to which RMR LLC or its subsidiaries provide management services, including FVE, in their capacities as officers or employees of RMR LLC.

Leases with RMR LLC. The Company leases office space to RMR LLC in certain of the Company's properties for RMR LLC's property management offices. Pursuant to the Company's lease agreements with RMR LLC, the Company recognized rental income from RMR LLC for leased office space of approximately $0.3 million for the year ended December 31, 2017. The Company's office space leases with RMR LLC are terminable by RMR LLC if the Company's management agreements with RMR LLC are terminated.

Other. The Company has in the past held, and likely will in the future hold, business meetings at hotels operated by Sonesta, which is owned in part by one of the Company's Managing Trustees, Adam D. Portnoy, and the remainder was owned by Barry M. Portnoy until his death and which manages certain hotels owned by HPT, and the Company's Trustees and officers have in the past stayed, and are likely in the future to stay, overnight at hotels operated by Sonesta when traveling for Company business. The Company pays Sonesta for the use of meeting space and related services and pays Sonesta or reimburses the Company's Trustees and officers for the costs of these hotel stays.

Relationship with AIC. The Company, ABP Trust, FVE and four other companies to which RMR LLC provides management services currently own AIC, an Indiana insurance company, in equal amounts and are parties to a shareholders agreement regarding AIC.

All of the Company's Trustees (other than Jennifer B. Clark) and most of the trustees and directors of the other AIC shareholders currently serve on the board of directors of AIC. Jennifer B. Clark serves as president and secretary of AIC. RMR LLC provides management and administrative services to AIC pursuant to a management and administrative services agreement with AIC. Pursuant to this agreement, AIC pays RMR LLC a service fee equal to 3.0% of the total annual net earned premiums payable under then active policies issued or underwritten by AIC or by a vendor or an agent of AIC on its behalf or in furtherance of AIC's business.

The Company and the other AIC shareholders participate in a combined property insurance program arranged and insured or reinsured in part by AIC. The Company also has a one year standalone insurance policy that provides coverage for the MOB (two buildings) located in Boston, Massachusetts that is owned in the Company's joint venture arrangement, which it obtained as a part of this insurance program. The Company (including the consolidated joint venture) paid aggregate annual premiums, including taxes and fees, of approximately $2.4 million in connection with this insurance program for the policy year ending June 30, 2018, which amount may be adjusted from time to time as the Company acquires or disposes of properties that are included in this insurance program.

Directors' and Officers' Liability Insurance. The Company, RMR Inc. and certain other companies to which RMR LLC or its subsidiaries provide management services, including FVE, participate in a combined directors' and officers' liability insurance policy. This combined policy expires in September 2019. The Company paid an aggregate premium of approximately $0.3 million for this policy.

The foregoing descriptions of the Company's agreements with RMR Inc., RMR LLC, FVE, AIC and other related persons are summaries and are qualified in their entirety by the terms of the agreements. A further description of the terms of certain of those agreements is included in the Annual Report. In addition, copies of certain of the agreements evidencing these relationships are filed with the SEC and may be obtained from the SEC's website, www.sec.gov. The Company may engage in additional transactions with related persons, including businesses to which RMR LLC or its subsidiaries provide management services.

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SECTION 16(a) BENEFICIAL OWNERSHIP REPORTING COMPLIANCE

Executive officers, Trustees and certain persons who own more than 10.0% of the outstanding Common Shares are required by Section 16(a) of the Exchange Act and related regulations:

•

to file reports of their ownership of Common Shares with the SEC and the Nasdaq; and



•

to furnish the Company with copies of the reports.

To the Company's knowledge, based solely on review of the copies of such reports furnished to us and written representations that no other reports were required, during the fiscal year ended December 31, 2017, our executive officers, Trustees and greater than 10.0% beneficial owners timely filed all required Section 16(a) reports.

OWNERSHIP OF EQUITY SECURITIES OF THE COMPANY

The following table sets forth information regarding the beneficial ownership of then outstanding Common Shares by each Trustee nominee, each Trustee, each of our named executive officers, and our Trustees, Trustee nominees and executive officers as a group, all as of March 30, 2018. Unless otherwise noted, to the Company's knowledge, voting power and investment power in the Common Shares are exercisable solely by the named person and the principal business address of the named person is c/o Senior Housing Properties Trust, Two Newton Place, 255 Washington Street, Suite 300, Newton, Massachusetts 02458.

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Set forth in the table below is information about the number of shares held by persons the Company knows to be the beneficial owners of more than 5.0% of the Common Shares.

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COMPENSATION DISCUSSION AND ANALYSIS

This Compensation Discussion and Analysis provides a detailed description of the Company's executive compensation philosophy and programs, the compensation decisions the Compensation Committee made under those programs in 2017 and the factors that impacted those decisions. This Compensation Discussion and Analysis discusses the compensation of the Company's "named executive officers" for 2017, who are the officers for whom compensation disclosure is required to be made in this Proxy Statement under SEC rules. For 2017, the Company's named executive officers were:

The Company does not have any employees. The Company's manager, RMR LLC, provides services that otherwise would be provided by employees. The Company's named executive officers are employees of RMR LLC. RMR LLC conducts the Company's day to day operations on the Company's behalf and compensates the Company's named executive officers, Messrs. Hegarty and Siedel, directly and in its sole discretion in connection with their services rendered to the Company and to RMR LLC. The Company does not pay its named executive officers salaries or bonuses or provide other compensatory benefits except for the grants of shares under the Company's 2012 Equity Compensation Plan (the "Share Award Plan"), discussed below. The Company does not reimburse RMR LLC for compensation RMR LLC pays to the Company's named executive officers. Neither of the Company's named executive officers has an employment agreement with the Company. In addition, except for the share award agreements discussed below under "Potential Payments upon Termination or Change in Control," neither of the Company's named executive officers has an agreement that provides for payments or benefits upon or in connection with his termination or a change in control of the Company. Although the Compensation Committee reviews and approves the Company's business management and property

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management agreements with RMR LLC, it is not involved in compensation decisions made by RMR LLC for its employees other than the employee serving as the Company's Director of Internal Audit. The Company's payments to RMR LLC are described in "Certain Related Person Transactions" beginning on page 37 of this Proxy Statement. For information regarding the compensation paid by RMR LLC and RMR Inc. to the named executive officers of RMR Inc., please see the below "RMR LLC and RMR Inc. Compensation Practices" section and the documents filed by RMR Inc. with the SEC, including its Annual Report on Form 10-K for the fiscal year ended September 30, 2017 and its Proxy Statement on Schedule 14A for its 2018 Annual Meeting of Shareholders. RMR Inc.'s filings with the SEC are not incorporated by reference into this Proxy Statement.

The Company's compensation program for its executive officers consists of grants of shares under the Share Award Plan. The Compensation Committee believes that these share grants recognize the Company's executive officers' scope of responsibilities, reward demonstrated performance and leadership, motivate future performance and further align the interests of the executive officers with those of the Company's shareholders.

In September 2017, the Chair of the Compensation Committee met with Mr. Barry M. Portnoy, our then Managing Trustee, and the chairs of the compensation committees of RMR Inc. and of the then other public companies to which RMR LLC provides management services, which included: the Company; GOV; HPT; SIR; FVE; and TA. The purposes of this meeting were, among other things, to discuss compensation philosophy and factors that may affect compensation decisions, to consider the compensation payable to the Company's Director of Internal Audit (who provides services to the Company and to other companies to which RMR LLC provides management services), to consider the allocation of internal audit and related services costs among RMR Inc., the Company and other companies to which RMR LLC provides such services, to provide a comparative understanding of potential share grants by the Company and the other companies to which RMR LLC provides management services and to hear and consider recommendations from the Company's then Managing Trustees concerning potential share grants. The share grants made by the other companies managed by RMR LLC are considered to be appropriate comparisons because of the similarities between certain services the Company requires from the Company's share grantees and the services provided by grantees providing similar services to these other companies. Subsequent to this meeting, the members of the Compensation Committee held a meeting at which the Committee Chair provided a report of the information discussed with Mr. Barry M. Portnoy and others, and made recommendations for share grants to the Company's named executive officers. The Compensation Committee then discussed these recommendations and other factors, including the following factors for the 2017 share grants: (i) the value of the proposed share grants; (ii) the historical awards previously granted to each named executive officer and the corresponding values at the time of the grants; (iii) the recommendations of RMR LLC as presented by Mr. Barry M. Portnoy; (iv) the value of share grants to executive officers providing comparable services at the applicable Other RMR Managed REITs and companies to which RMR LLC provides management services; (v) the scope of, and any changes to, the responsibilities assigned to, or assumed by, each named executive officer during the past year and on a going forward basis; (vi) the length of historical services by each named executive officer; (vii) the Compensation Committee's perception regarding the quality of the services provided by each named executive officer in carrying out those responsibilities; and (viii) the Company's financial and operating performance in the past year and the Company's perceived future prospects. The Compensation Committee considered these multiple factors in determining whether to increase or decrease the amounts of the prior year's grants. There was no formulaic approach in the use of these various factors in determining the number of shares to award to each named executive officer. The share amounts were determined on a subjective basis, using the various factors in the Compensation Committee's sole discretion. The named executive officers did not participate in these meetings and were not involved in determining or recommending the amount or form of named executive compensation they receive from the Company.

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Although the Company does not pay any cash compensation directly to its officers and has no employees, the Company has adopted the Share Award Plan to reward the Company's named executive officers and other RMR LLC employees who provide services to the Company and to foster a continuing identity of interest between them and the Company's shareholders. The Company awards shares under the Share Award Plan to recognize the named executive officers' scope of responsibilities, reward demonstrated performance and leadership, motivate future performance, align the interests of the Company's executives with those of the Company's other shareholders and motivate the executives to remain employees of the Company's manager and to continue to provide services to the Company through the term of the awards.

Under its charter, the Compensation Committee evaluates, approves and administers the Company's equity compensation plans, which currently consist solely of the Share Award Plan. The Compensation Committee has historically determined to use grants of Common Share awards under the Share Award Plan rather than stock options as equity compensation. Because the value of the Common Shares may be determined in part by reference to its dividend yield relative to market interest rates rather than by its potential for capital appreciation, the Company believes a conventional stock option plan might not provide appropriate incentives for management for a business like that of the Company, but a share grant plan may create a better identity of interests between management and other shareholders. Also, because the Company believes a stock option plan could have the potential to encourage excessive short term risk taking, the Company has historically granted share awards rather than stock options.

The Compensation Committee uses comparative information about the applicable Other RMR Managed REITs as additional data to help it determine whether it is awarding share amounts that are reasonable based on the characteristics of those REITs and their respective officers. The Compensation Committee also considers the size and structure of the Other RMR Managed REITs and other RMR LLC managed businesses, and the experience, length of service and scope of duties and responsibilities of the officers at these other companies to assess the appropriateness of the value of the share awards proposed for the Company's officers in light of the proposed awards for officers with comparable roles at the other companies. The Compensation Committee reviewed the compensation data regarding the applicable Other RMR Managed REITs and their officers, together with the other factors discussed above, but the Compensation Committee did not undertake a detailed comparison of the named executive officers across the REITs or other companies managed by RMR LLC or assign weight to any particular characteristic of these other companies or their officers because the Compensation Committee determines the share amounts in its sole discretion on a non-formulaic basis. In 2017, the Compensation Committee considered the foregoing factors and decided to award a greater number of shares to Mr. Siedel than were awarded in 2016 and the same number of shares to Mr. Hegarty as were awarded in 2016, in accordance with the recommendation of the Company's Managing Trustees and the Chair of the Compensation Committee. The Compensation Committee determined to grant a larger number of shares to Mr. Hegarty than to Mr. Siedel due to Mr. Hegarty's more senior position and his greater length of service to the Company. The Compensation Committee also determined that it would be appropriate to provide that such share awards would vest upon the occurrence of certain corporate "change in control" or termination events. For more information on potential payments upon such events, see page 58.

The Company determines the fair market value of the shares granted based on the closing price of the Common Shares on the date of grant. The Compensation Committee has imposed, and may impose, vesting and other conditions on the granted Common Shares because it believes that time based vesting encourages the recipients of the share awards to remain employed by RMR LLC and to continue to provide services to the Company. The Compensation Committee currently uses a vesting schedule under which one fifth of the shares vest immediately and the remaining shares vest in four equal, consecutive annual installments commencing on the first anniversary of the date of grant. The Compensation Committee utilizes a four year time based vesting schedule to provide an incentive to provide services for a long term and in consideration of the tax treatment of the share grants to the Company and to the recipients. In the event a recipient who has been granted a share award ceases to perform duties for the Company or ceases to be an officer or an employee of RMR LLC or any company that RMR LLC or its

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subsidiaries manage during the vesting period, the Company may cause the forfeiture of, or the Company may repurchase for nominal consideration, the Common Shares that have not yet vested. As with other issued Common Shares, vested and unvested shares awarded under the Share Award Plan are entitled to receive distributions that the Company makes, if any, on the Common Shares.

Because the consideration of share awards by the Compensation Committee and the Board is determined on a regular schedule (i.e., in September for the Company's officers and employees of RMR LLC and at the first meeting of the Board after the annual meeting of shareholders for the Trustees), the proximity of any grants to earnings announcements or other market events, if any, is coincidental.

The Compensation Committee believes that its compensation philosophy and programs are designed to foster a business culture that aligns the interests of its named executive officers with those of its shareholders. The Compensation Committee believes that the equity compensation of its named executive officers is appropriate to the goal of providing shareholders dependable, long term returns.

The Company's current policy, consistent with the prior vote of the Company's shareholders, is to provide shareholders with an opportunity to approve, on an advisory basis, the compensation of named executive officers each year at the annual meeting of shareholders. Accordingly, the Company is providing shareholders with an opportunity to approve the compensation of the named executive officers in this Proxy Statement. For more information, see Item 2 on page 60 of this Proxy Statement.

In evaluating the Company's compensation process for 2017, the Compensation Committee generally considered the results of the most recent advisory vote of the Company's shareholders on the compensation of the executive officers named in the proxy statement for the Company's 2017 annual meeting of shareholders.

As explained above, the Company's manager, RMR LLC, provides services that otherwise would be provided by employees, conducts the Company's day to day operations on the Company's behalf and compensates the Company's named executive officers, Messrs. Hegarty and Siedel, directly and in its sole discretion in connection with their services rendered to the Company and to RMR LLC. The Company does not pay its named executive officers salaries or bonuses or provide other compensatory benefits except for the grants of share awards under the Share Award Plan. The Company does not reimburse RMR LLC for compensation RMR LLC or RMR Inc. pays to the Company's named executive officers.

RMR LLC has advised the Company that in 2017 RMR LLC paid each of the Company's named executive officers cash compensation comprised of a fixed salary and a cash bonus. RMR LLC did not provide guaranteed cash bonuses to the Company's named executive officers during 2017 and did not set specific performance targets on which bonuses would be payable to them. Instead, the annual cash bonuses paid by RMR LLC to the Company's named executive officers in 2017 were discretionary in amount and were based on a performance evaluation conducted by the compensation committee of RMR Inc.

RMR Inc., the parent of RMR LLC, granted awards of 4,000 shares and 900 shares of Class A common stock of RMR Inc., with grant date fair values of $204,200 and $45,945, to Mr. Hegarty and Mr. Siedel, respectively, in 2017. One fifth of the shares awarded vested on the grant date and an additional one fifth vests on each of the next four anniversaries of the grant date, subject to the applicable named executive officer continuing to render significant services, whether as an employee or otherwise, to RMR LLC or a public client company managed by RMR LLC or their respective affiliates and to accelerated vesting under certain circumstances.

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The Company's named executive officers are also officers and employees of RMR LLC and, as officers and employees of RMR LLC, also provide services to RMR LLC, RMR Inc. and other companies managed by RMR LLC or its subsidiaries. RMR LLC has informed the Company that the cash compensation paid by RMR LLC to the Company's named executive officers is for services provided by the officers to RMR LLC, RMR Inc., the Company and other companies managed by RMR LLC or its subsidiaries. RMR LLC has also informed the Company that it is not able to allocate with reasonable certainty or provide a reasonable estimate of the compensation paid by RMR LLC to our named executive officers for their services to the Company for a number of reasons:

•

Our management agreements with RMR LLC do not require individual executive officers to dedicate a specific amount of time to providing services to the Company under those agreements. RMR LLC's officers and employees provide services on an as needed basis across RMR LLC, RMR Inc., the Company and all other companies managed by RMR LLC or its subsidiaries.



•

Our management agreements with RMR LLC do not require that a specified amount or percentage of the fees the Company pays to RMR LLC be allocated to the Company's executive officers.



•

RMR LLC does not designate a specific amount of time that the Company's named executive officers must spend providing services to the Company or record the amount of time that the Company's named executive officers (or any other employee of RMR LLC) spend providing services to the Company.

For information regarding the compensation paid by RMR LLC and RMR Inc. to the named executive officers of RMR Inc., please see the documents filed by RMR Inc. with the SEC, including its Annual Report on Form 10-K for the fiscal year ended September 30, 2017 and its Proxy Statement on Schedule 14A for its 2018 Annual Meeting of Shareholders. RMR Inc.'s filings with the SEC are not incorporated by reference into this Proxy Statement.

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REPORT OF THE COMPENSATION COMMITTEE

The Compensation Committee has reviewed and discussed the Compensation Discussion and Analysis required by Item 402(b) of Regulation S-K with management. Based on such review and discussions, the Compensation Committee recommended to the Board that the Compensation Discussion and Analysis be included in this Proxy Statement and incorporated by reference into the Annual Report on Form 10-K for the year ended December 31, 2017.

COMPENSATION COMMITTEE INTERLOCKS AND INSIDER PARTICIPATION

The Compensation Committee is comprised entirely of the three Independent Trustees listed above. No member of the Compensation Committee is a current, or during 2017 was a former, officer or employee of the Company. In 2017, none of the Company's executive officers served (i) on the compensation committee of any entity that had one or more of its executive officers serving on the Board or the Compensation Committee of the Company or (ii) on the board of directors or board of trustees of any entity that had one or more of its executive officers serving on the Compensation Committee of the Company. Members of the Compensation Committee serve as independent trustees or independent directors and compensation committee members of other public companies to which RMR LLC provides management services. Mr. Somers serves as an independent trustee of GOV, SIR, RIF and TRMT. Mr. Harrington serves as an independent trustee of GOV, HPT, RIF and TRMT. Ms. Harris Jones serves as an independent trustee of ILPT and an independent director of TA. In addition, each of our Independent Trustees serves as a director of AIC. The disclosures regarding our relationships with these foregoing entities and certain transactions with or involving them under the section entitled "Certain Related Person Transactions" are incorporated by reference herein.

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EXECUTIVE COMPENSATION

The following tables and footnotes summarize the total compensation of the Company's President and Chief Operating Officer and the Chief Financial Officer and Treasurer who were serving as such officers as of December 31, 2017, or the Company's "named executive officers." Neither of the Company's named executive officers is employed by the Company. The Company's manager, RMR LLC, provides services that otherwise would be provided by employees and employs and compensates the Company's named executive officers directly and in RMR LLC's sole discretion in connection with their services rendered to RMR LLC and to the Company. For information regarding the compensation paid by the Company to RMR LLC, please see the above "Related Person Transactions" section. For information regarding the compensation paid by RMR LLC and RMR Inc. to the named executive officers of RMR Inc., please see the above "RMR LLC and RMR Inc. Compensation Practices" section and the documents filed by RMR Inc. with the SEC, including its Annual Report on Form 10-K for the fiscal year ended September 30, 2017 and its Proxy Statement on Schedule 14A for its 2018 Annual Meeting of Shareholders. RMR Inc.'s filings with the SEC are not incorporated by reference into this Proxy Statement. The Company does not pay the Company's named executive officers salaries or bonuses or provide other compensation or employee benefits except for the awards of Common Shares under the Share Award Plan.

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Share awards granted by the Company to the named executive officers in 2017 provide that one fifth of each award vested on the date of the award grant and an additional one fifth vests on each of the next four anniversaries of the grant date, subject to the applicable named executive officer continuing to render significant services, whether as an employee or otherwise, to the Company, RMR LLC or any company to which RMR LLC provides management services or their respective affiliates and to accelerated vesting under certain circumstances. Holders of vested and unvested Common Shares awarded under the Share Award Plan receive distributions that the Company makes, if any, on its shares on the same terms as other holders of the Common Shares.

The following table shows the total Common Shares awarded by the Company to its named executive officers in 2017.

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The following table shows Common Share awards made in 2017 and prior years to the Company's named executive officers that vested in 2017.

From time to time, we have entered into arrangements with former employees of RMR LLC in connection with the termination of their employment with RMR LLC, providing for the acceleration of vesting of Common Shares previously awarded to them under the Share Award Plan. Although we have no formal policy, plan or arrangement for payments to employees of RMR LLC in connection with their termination of employment with RMR LLC, we may in the future provide on a discretionary basis for similar payments depending on various factors we then consider relevant and if we believe it is in our best interests to do so.

The form of share award agreement for awards made to our named executive officers provides for acceleration of vesting of all share awards upon the occurrence of certain change in control or termination events (each, a "Termination Event").

The following table describes the potential payments to our named executive officers upon a Termination Event, if such event had occurred, as of December 31, 2017.

For a discussion of the consequences of a Termination Event under the Company's business and property management agreements with RMR LLC, see the above "Related Person Transactions" section.

Pay ratio disclosure under Item 402(u) has not been provided because the Company does not have any employees.

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REPORT OF THE AUDIT COMMITTEE

In the course of the Audit Committee's oversight of the Company's financial reporting process, the Audit Committee has: (i) reviewed and discussed with management the audited financial statements for the fiscal year ended December 31, 2017; (ii) discussed with Ernst & Young LLP, the Company's independent auditors, the matters required to be discussed under PCAOB Auditing Standard No. 1301; (iii) received the written disclosures and the letter from the auditors required by applicable requirements of the Public Company Accounting Oversight Board regarding the independent auditors' communications with the Audit Committee concerning independence; (iv) discussed with the independent auditors their independence; and (v) considered whether the provision of non-audit services by the independent auditors is compatible with maintaining their independence and concluded that it is compatible at this time.

Based on the foregoing review and discussions, the Audit Committee recommended to the Board that the audited financial statements be included in the Annual Report on Form 10-K for the fiscal year ended December 31, 2017, for filing with the SEC.

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ADVISORY VOTE TO APPROVE EXECUTIVE
COMPENSATION (ITEM 2)

As required by Section 14A of the Exchange Act, the Company seeks a non-binding advisory vote from its shareholders to approve the compensation of its named executive officers as described in the "Compensation Discussion and Analysis" section beginning on page 50 and the "Executive Compensation" section beginning on page 56.

The Board recommends that shareholders vote FOR the following resolution:

RESOLVED: That the shareholders of the Company approve, on a non-binding, advisory basis, the compensation paid by the Company to the Company's named executive officers, as disclosed pursuant to Item 402 of Regulation S-K, including the "Compensation Discussion and Analysis" in this Proxy Statement.

Because your vote is advisory, it will not be binding upon the Board or the Compensation Committee. However, the Board values shareholders' opinions and the Compensation Committee will take into account the outcome of the vote when considering future executive compensation decisions.

Approval of the advisory vote to approve executive compensation requires the affirmative vote of a majority of all the votes cast, in person or by proxy, at the 2018 Annual Meeting.

The Board of Trustees recommends a vote "FOR" the advisory vote to approve executive compensation.

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RATIFICATION OF THE
APPOINTMENT OF ERNST & YOUNG LLP
AS INDEPENDENT AUDITORS (ITEM 3)

The Audit Committee has the sole authority and responsibility to hire, evaluate and, when appropriate, replace our independent auditors and is directly responsible for the appointment, compensation and general oversight of the work of the independent auditors. The Audit Committee is responsible for approving the audit and permissible non-audit services provided by the independent auditors and the associated fees.

The Audit Committee evaluates the performance of our independent auditors annually and determines whether to reengage the current independent auditors or consider other audit firms. In doing so, the Audit Committee considers the quality and efficiency of the services provided by the auditors, the auditors' technical expertise and knowledge of our operations and industry, the auditors' independence, legal proceedings involving the auditors, the results of PCAOB inspections and peer quality reviews of the auditors and the auditors' reputation in the marketplace. In connection with the mandated rotation of the independent auditors' lead engagement partner, the Audit Committee and its chair consider the selection of the new lead engagement partner identified by the independent auditors.

Based on this evaluation, the Audit Committee has appointed Ernst & Young LLP to serve as the Company's independent auditors for the fiscal year ending December 31, 2018. Ernst & Young LLP has served as the Company's independent auditors since our formation in 1999 and is considered by management and the Audit Committee to be well qualified. Further, the Audit Committee and the Board believe that the continued retention of Ernst & Young LLP to serve as the independent registered public accounting firm is in the best interests of the Company and its shareholders.

The Audit Committee has determined to submit its selection of the independent auditors to the Company's shareholders for ratification. This vote will ratify prior action by the Audit Committee and will not be binding upon the Audit Committee. However, the Audit Committee may reconsider its prior appointment of the independent auditors or consider the results of this vote when it determines to appoint our independent auditors in the future.

The following table shows the fees for audit and other services provided to us by Ernst & Young LLP for the fiscal years ended December 31, 2017 and 2016.

Audit Fees. This category includes fees associated with the annual financial statements audit and related audit procedures, the audit of internal control over financial reporting, work performed in connection with

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any registration statements and any applicable Current Reports on Form 8-K and the review of any of the Company's Quarterly Reports on Form 10-Q.

Audit Related Fees. This category consists of services that are reasonably related to the performance of the audit or review of financial statements and are not included in "Audit Fees." These services principally include due diligence in connection with acquisitions, consultation on accounting and internal control matters, audits in connection with proposed or consummated acquisitions, information systems audits and other attest services.

Tax Fees. This category consists of fees for tax services, including tax compliance, tax advice and tax planning.

All Other Fees. This category consists of services that are not included in the above categories. The amounts for 2017 and 2016 reflect annual subscription fees for Ernst & Young LLP's online accounting research application.

The Audit Committee has established policies and procedures that are intended to control the services provided by our independent auditors and to monitor their continuing independence. Under these policies, no services may be undertaken by our independent auditors unless the engagement is specifically approved by the Audit Committee or the services are included within a category that has been approved by the Audit Committee. The maximum charge for services is established by the Audit Committee when the specific engagement or the category of services is approved. In certain circumstances, our management is required to notify the Audit Committee when approved services are undertaken and the Audit Committee or its Chair may approve amendments or modifications to the engagement or the maximum fees. Our Director of Internal Audit is responsible for reporting to the Audit Committee regarding compliance with these policies and procedures.

The Audit Committee will not approve engagements of the independent auditors to perform non-audit services for the Company if doing so will cause the independent auditors to cease to be independent within the meaning of applicable SEC or Nasdaq rules. In other circumstances, the Audit Committee considers, among other things, whether our independent auditors are able to provide the required services in a more or less effective and efficient manner than other available service providers and whether the services are consistent with the Public Company Accounting Oversight Board Rules.

All services for which the Company engaged its independent auditors in 2017 and 2016 were approved by the Audit Committee. The total fees for audit and non-audit services provided by Ernst & Young LLP in 2017 and 2016 are set forth above and, for 2017, include estimated fee amounts. The tax fees charged by Ernst & Young LLP during 2017 and 2016 were for tax compliance services, including those related to the Company's income tax returns for the fiscal years ended December 31, 2016 and 2015, respectively. The Audit Committee approved the engagement of Ernst & Young LLP to provide these non-audit services because it determined that Ernst & Young LLP providing these services would not compromise Ernst & Young LLP's independence and that the firm's familiarity with our record keeping and accounting systems would permit the firm to provide these services with equal or higher quality, more efficiently and at a lower cost than the Company could obtain these services from other providers.

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The Company has been advised by Ernst & Young LLP that neither the firm, nor any member of the firm, has any material interest, direct or indirect, in any capacity in the Company or its subsidiaries.

One or more representatives of Ernst & Young LLP will be present at the 2018 Annual Meeting. The representatives will have an opportunity to make a statement if they desire to do so and will be available to respond to appropriate questions.

Ratification of the appointment of the independent auditors requires the affirmative vote of a majority of all the votes cast, in person or by proxy, at the 2018 Annual Meeting. If shareholders fail to approve the proposal, the Board may reconsider its prior appointment of the independent auditors or consider the results of this vote when it determines to appoint our independent auditors in the future.

The Board of Trustees recommends a vote "FOR" the ratification of the appointment of Ernst & Young LLP as independent auditors.

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SENIOR HOUSING PROPERTIES TRUST     2018 Proxy Statement    63

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OTHER INFORMATION

At this time, the Company knows of no other matters that will be brought before the meeting. If, however, other matters properly come before the meeting or any postponement or adjournment thereof, the persons named in the accompanying proxy card intend to vote the shares for which they have been appointed or authorized as proxy in accordance with their discretion on such matters to the maximum extent that they are permitted to do so by applicable law.

Jennifer B. Clark
Secretary

Newton, Massachusetts
April 3, 2018

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64    SENIOR HOUSING PROPERTIES TRUST     2018 Proxy Statement

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THANK YOU

Thank you for being a shareholder of Senior Housing Properties Trust.

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QuickLinks

Notice of 2018 Annual Meeting of Shareholders and Proxy Statement
Audit Committee
Compensation Committee
Nominating and Governance Committee