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

SCHEDULE 14A

SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section 14(a) of
the Securities Exchange Act of 1934

 

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To the Shareholders of CommonWealth REIT:

        Notice is hereby given that the annual meeting of shareholders of CommonWealth REIT, a Maryland real estate investment trust, will be held at 9:30 a.m., local time, on Tuesday, May 14, 2013, at Two Newton Place, 255 Washington Street, Suite 100, Newton, Massachusetts 02458 for the following purposes:

1.

To elect the nominee named in our proxy statement to our Board of Trustees as the Independent Trustee in Group III ("proposal 1").



2.

To hold an advisory vote relating to our executive compensation ("proposal 2").



3.

To ratify the appointment of Ernst & Young LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2013 ("proposal 3").



4.

To consider and vote upon such other matters as may properly come before the meeting and at any adjournments or postponements thereof.

        OUR BOARD OF TRUSTEES UNANIMOUSLY RECOMMENDS THAT YOU VOTE "FOR" THE NOMINEE FOR TRUSTEE IN PROPOSAL 1 AND "FOR" PROPOSALS 2 AND 3.

        We encourage you to contact the firm assisting us in the solicitation of proxies, Innisfree M&A Incorporated, or Innisfree, if you have any questions or need assistance in voting your shares. Banks and brokers may call Innisfree, collect, at (212) 750-5833. Shareholders may call Innisfree, toll-free, at (877) 717-3922.

        Shareholders of record at the close of business on February 19, 2013, are entitled to notice of, and to vote at, the meeting and at any adjournment or postponement thereof.

        Securities and Exchange Commission rules allow us to furnish proxy materials to our shareholders on the internet. You can now access proxy materials and authorize a proxy to vote your shares at www.proxyvote.com. You may also authorize a proxy to vote your shares over the internet or by telephone by following the instructions on that website. In order to vote over the internet or by telephone you must have your shareholder identification number, which is set forth in the Notice Regarding the Availability of Proxy Materials mailed to you. If your shares are held in the name of a brokerage firm, bank, nominee or other institution, you should provide instructions to your broker, bank, nominee or other institution on how to vote your shares. You may also request a paper proxy card to submit your vote by mail. If you attend the meeting and vote in person, that vote will revoke any proxy you previously submitted. If you hold shares in the name of a brokerage firm, bank, nominee or other institution, you must provide a legal proxy from that institution in order to vote your shares at the meeting. Whether or not you plan to attend the meeting, please read the proxy statement and complete or authorize a proxy for your shares as soon as possible. Your vote is important, no matter how many or how few shares you own.

Newton, Massachusetts
February 25, 2013

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COMMONWEALTH REIT
Two Newton Place
255 Washington Street, Suite 300
Newton, Massachusetts 02458

PROXY STATEMENT
FOR THE
ANNUAL MEETING OF SHAREHOLDERS

To be held at 9:30 a.m. on Tuesday, May 14, 2013
at
Two Newton Place
255 Washington Street, Suite 100
Newton, Massachusetts 02458

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INTRODUCTION

        A notice of the annual meeting of shareholders of CommonWealth REIT, a Maryland real estate investment trust, or the Company, is on the preceding page and a form of proxy solicited by our Board of Trustees, or our Board, accompanies this proxy statement. This proxy statement and a form of proxy, together with our annual report to shareholders for the year ended December 31, 2012, are first being made available, and a Notice Regarding the Availability of Proxy Materials, or the Notice of Internet Availability, is first being mailed, to shareholders on or about February 25, 2013.

        The annual meeting record date is February 19, 2013. Only shareholders of record at the close of business on February 19, 2013, are entitled to notice of, and to vote at, the meeting and at any postponement or adjournment thereof. We had 83,804,068 common shares of beneficial interest, $0.01 par value per share, or common shares, outstanding on the record date and entitled to vote at the meeting. Our common shares are listed on the New York Stock Exchange, or NYSE. The holders of our outstanding common shares are entitled to one vote per common share.

        A quorum of shareholders is required for shareholders to take action at the meeting, except that the shareholders entitled to vote at the meeting may adjourn the meeting if less than a quorum is present at the meeting. The presence, in person or by proxy, of holders of common shares entitled to cast a majority of all the votes entitled to be cast at the meeting shall constitute a quorum. Common shares represented by valid proxies will count for the purpose of determining the presence of a quorum for the meeting. Abstentions and broker non-votes, if any, will be treated as shares present for purposes of determining whether a quorum is present. Failure of a quorum to be present at the meeting will necessitate adjournment of the meeting and will subject us to additional expense. Under our bylaws, the chairperson of the meeting may adjourn the meeting if less than a quorum is present at the meeting.

        The affirmative vote of a majority of the votes cast will be necessary to elect the nominee for Trustee described in proposal 1, to approve the resolution regarding named executive officer compensation described in proposal 2 and to ratify the appointment of Ernst & Young LLP as our independent registered public accounting firm in proposal 3. Proposals 2 and 3 are nonbinding shareholder advisory votes and, if approved, would serve only as recommendations to our Board.

        The individuals named as proxies on a properly completed proxy will vote in accordance with your directions as indicated thereon. If you properly complete your proxy and give no voting instructions, your shares will be voted "FOR" the nominee for Trustee in proposal 1 and "FOR" proposals 2 and 3.

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        Shareholders of record may authorize a proxy to vote their shares over the internet or by telephone in the manner provided on the website indicated in the Notice of Internet Availability mailed to them, or, if they requested and received paper or email copies of proxy materials, by completing and returning the proxy card or by attending the meeting and voting in person. Proxies submitted by mail, over the internet or by telephone must be received by 11:59 p.m. Eastern Time on Monday, May 13, 2013.

        Broker non-votes occur in respect of shares held in street name when the broker indicates that voting instructions for a particular matter have not been received from the beneficial owners or other persons entitled to vote those shares and the broker does not have discretionary voting authority to vote those shares on that particular matter. Broker non-votes and abstentions will have no effect on the outcome of any of the proposals. A proxy marked "WITHHOLD" will have the same effect as an abstention.

        The record date for the meeting will apply to any adjournment or postponement of the meeting unless our Board fixes a new record date for the adjourned or postponed meeting. If we adjourn the annual meeting, we will announce the time and place of the adjourned meeting at the original meeting, but we do not intend to deliver another notice of the meeting unless we fix a new record date for the adjourned meeting. At any subsequent reconvening of the annual meeting, all proxies will be voted in the same manner as they would have been at the original convening of the meeting (except for any proxies that have been effectively revoked or withdrawn).

        IMPORTANT: If your shares are held in the name of a brokerage firm, bank, nominee or other institution, you should provide instructions to your broker, bank, nominee or other institution on how to vote your shares. Please contact the person responsible for your account and give instructions for a proxy to be completed for your shares. If you have any questions or need assistance in voting your shares, please call the firm assisting us in the solicitation of proxies:

Innisfree M&A Incorporated
501 Madison Avenue, 20th Floor
New York, New York 10022
Brokers and Banks Call Collect at (212) 750-5833
Shareholders Call Toll-Free at (877) 717-3922

        A shareholder of record who has given a proxy may revoke it any time prior to its exercise by delivering to our Secretary at Two Newton Place, 255 Washington Street, Suite 300, Newton, Massachusetts 02458, a written revocation, by delivering a duly executed proxy bearing a later date, by authorizing at a later date a proxy to vote his or her common shares over the internet or by telephone in the manner provided on the website indicated in the Notice of Internet Availability or by attending the meeting and voting his or her common shares in person. If a shareholder of record wants to receive a paper or email copy of the proxy card, he or she may request one from our Secretary at Two Newton Place, 255 Washington Street, Suite 300, Newton, Massachusetts 02458. Proxies submitted by mail, over the internet or by telephone must be received by 11:59 p.m. Eastern Time on May 13, 2013. If your shares are held in the name of a brokerage firm, bank, nominee or other institution and you wish to change a prior instruction you gave to your brokerage firm, bank, nominee or other institution to vote your shares, you must follow the brokerage firm's, bank's, nominee's or other institution's instructions for changing your prior voting instructions. In addition, if you hold shares in the name of a brokerage

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firm, bank, nominee or other institution, you must provide a legal proxy from that institution in order to vote your shares at the meeting.

        Our principal executive offices are located at Two Newton Place, 255 Washington Street, Suite 300, Newton, Massachusetts 02458.

        Our website address is included in this proxy statement as a textual reference only, and the information in the website is not incorporated by reference into this proxy statement.

Notice Regarding the Availability of Proxy Materials

        From the date of mailing of the Notice of Internet Availability through the conclusion of the meeting, shareholders will be able to access all of the proxy materials on the internet at www.proxyvote.com. The proxy materials will be available free of charge. The Notice of Internet Availability will instruct you as to how you may access and review all of the important information contained in the proxy materials (including our annual report to shareholders) over the internet or through other methods specified at the website designated in the Notice of Internet Availability. The website designated contains instructions as to how to vote over the internet or by telephone. The Notice of Internet Availability also instructs you as to how you may request a paper or email copy of the proxy card. If you received a Notice of Internet Availability and would like to receive printed copies of the proxy materials, you should follow the instructions for requesting such materials included in the Notice of Internet Availability.

PROPOSAL 1
ELECTION OF TRUSTEE

        The number of our Trustees is fixed at five, and our Board is divided into three groups, with two Trustees in Group I, two Trustees in Group II and one Trustee in Group III. Trustees in each group are elected for three year terms and serve until their successors are elected and qualified.

        Our current Trustees are Joseph L. Morea in Group III with a term of office expiring at the meeting to which this proxy statement relates, Barry M. Portnoy and Frederick N. Zeytoonjian in Group I with a term of office expiring at our 2014 annual meeting of shareholders and William A. Lamkin and Adam D. Portnoy in Group II with a term of office expiring at our 2015 annual meeting of shareholders. The term of the Group III Trustee elected at the meeting to which this proxy statement relates will expire at our 2016 annual meeting of shareholders.

        Our Trustees are also categorized as Independent Trustees or Managing Trustees. Our Board is composed of three Independent Trustees and two Managing Trustees. Our Independent Trustees are not employees or affiliates, as such term is defined in our declaration of trust and our bylaws, of Reit Management & Research LLC, or RMR, our manager, do not have a material business or professional relationship with RMR or any other person or entity that holds in excess of 9.8% of our issued and outstanding shares of beneficial interest, are not involved in our day to day activities, do not perform services for us except in their capacity as Trustee and are persons who qualify as independent under our declaration of trust, our bylaws and the applicable rules of the NYSE and the Securities and Exchange Commission, or SEC. Our Managing Trustees are not Independent Trustees and have been employees of RMR or involved in our day to day activities for at least one year. Messrs. Lamkin, Morea and Zeytoonjian are our Independent Trustees, and Messrs. Adam Portnoy and Barry Portnoy

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are our Managing Trustees. Biographical information relating to our Trustees and other information relating to our Board appears elsewhere in this proxy statement.

        Our Board has nominated Mr. Joseph L. Morea for election as the Independent Trustee in Group III, whose nomination was recommended to our Board by our Nominating and Governance Committee. The term of the Independent Trustee in Group III elected at the meeting will expire at our 2016 annual meeting of shareholders. The persons named in the accompanying proxy intend to exercise properly executed and delivered proxies "FOR" the election of Mr. Morea, except to the extent that properly completed proxies indicate that the votes should not be so cast.

        Mr. Morea has agreed to serve as the Independent Trustee in Group III if elected. If, however, Mr. Morea becomes unable or unwilling to accept election to our Board, the proxies will be voted for the election of a substitute nominee designated by our Board. Our Board has no reason to believe that Mr. Morea will be unable or unwilling to serve.

        The affirmative vote of a majority of the votes cast will be necessary to elect Mr. Morea as the Independent Trustee in Group III.

        Our Board recommends you vote "FOR" the election of Mr. Morea as the Independent Trustee in Group III.

PROPOSAL 2
ADVISORY APPROVAL RELATING TO EXECUTIVE COMPENSATION

        Pursuant to Section 14A of the Securities Exchange Act of 1934, as amended, or the Exchange Act, we are including a proposal for our shareholders to vote to approve, on a nonbinding, advisory basis, the compensation of those of our executive officers listed in the Summary Compensation Table for 2012, 2011 and 2010 in this proxy statement, or our named executive officers, as disclosed pursuant to Item 402 of Regulation S-K in this proxy statement.

        We do not have any employees. Our manager, RMR, conducts our day to day operations on our behalf and provides services to us that otherwise would be provided by employees. Each of our named executive officers is an employee of RMR and the officers' services are provided to us by RMR. RMR compensates our named executive officers directly and in its sole discretion in connection with the officers' services rendered to RMR and to us. None of our named executive officers has an employment agreement with us and we do not pay them salaries or bonuses, or provide them other compensation or benefits, except for the grants of shares under our share award plan described in the Compensation Discussion and Analysis, Compensation Tables and narrative discussion in this proxy statement.

        We make grants of shares under our share award plan to reward our named executive officers and to foster a continuing identity of interest between them and our shareholders. We award shares under our share award plan to recognize our named executive officers' scope of responsibilities, reward demonstrated performance and leadership, motivate future performance, align the interests of our executives with those of our other shareholders and motivate our executives to remain employees of our manager and to continue to provide services to us through the term of the awards. Our award of shares under our share award plan is designed to reward executive performance that contributes to our success and increases shareholder value. For additional information on our share award plan, see the section captioned "Analysis of Grants under Our Share Award Plan" in this proxy statement.

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        We urge you to read the Compensation Discussion and Analysis, Compensation Tables and narrative discussion in this proxy statement for information about our compensation program, including the 2012 compensation of our named executive officers.

        We are asking you to vote to approve the adoption of the following resolution:

RESOLVED:    That the shareholders of the Company approve, on a nonbinding, advisory basis, the compensation paid to the Company's named executive officers, as disclosed pursuant to Item 402 of Regulation S-K, including the Compensation Discussion and Analysis, Compensation Tables and narrative discussion in this proxy statement.

        Our current policy is to provide shareholders with an opportunity to approve the compensation of our named executive officers each year at our annual meeting of shareholders. It is currently expected that the next such vote will occur at our 2014 annual meeting of shareholders.

        The affirmative vote of a majority of the votes cast will be necessary to approve proposal 2. The shareholder vote on proposal 2 is advisory and nonbinding, and serves only as a recommendation to our Board.

        Our Board recommends you vote "FOR" proposal 2.

PROPOSAL 3
RATIFICATION OF APPOINTMENT OF INDEPENDENT REGISTERED
PUBLIC ACCOUNTING FIRM

        On February 23, 2013, our Audit Committee voted to appoint Ernst & Young LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2013 (our fiscal year being a calendar year). Ernst & Young LLP acted as our independent registered public accounting firm for 2012 and 2011. A representative of Ernst & Young LLP is expected to be present at the meeting, with the opportunity to make a statement if he or she desires to do so. This representative will be available to respond to appropriate questions from shareholders who are present at the meeting. Proposal 3 is nonbinding. If the appointment is not ratified, our Audit Committee will consider whether to appoint another independent registered public accounting firm in its discretion. If the appointment is ratified, our Audit Committee, in its discretion, may appoint a different independent registered public accounting firm at any time if it determines that such a change would be advisable.

        The fees and expenses for services provided by Ernst & Young LLP to us for the last two fiscal years are listed in the table below and include fees for services provided to our consolidated public company subsidiary, Select Income REIT, or SIR, which completed its initial public offering, or IPO, in March 2012:

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        Our Audit Committee has established policies and procedures that are intended to control the services provided by our independent registered public accounting firm and to monitor their continuing independence. Under these policies, no services may be undertaken by our independent registered public accounting firm unless the engagement is specifically approved by our Audit Committee or the services are included within a category that has been approved by our Audit Committee. The maximum charge for services is established by our Audit Committee when the specific engagement or the category of services is approved. In certain circumstances, our management is required to notify our 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 to report to our Audit Committee regarding compliance with these policies and procedures.

        Our Audit Committee will not approve engagements of our independent registered public accounting firm to perform non-audit services for us if doing so will cause our independent registered public accounting firm to cease to be independent within the meaning of applicable SEC or NYSE rules. In other circumstances, our Audit Committee considers, among other things, whether our independent registered public accounting firm is 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 we engaged our independent registered public accounting firm in 2012 and 2011 were approved by our Audit Committee. The total fees for audit and non-audit services provided by Ernst & Young LLP in 2012 and 2011 are set forth above. The amount of audit fees for 2012 is based on the fees estimate previously provided by Ernst & Young LLP to and accepted by us for audit services provided to us by Ernst & Young LLP in connection with the audit of our 2012 financial statements. The final audit fees amount for the rendering of those services by Ernst & Young LLP may be more than the amount reflected in the table. The increase in audit fees from 2011 to 2012 reflect fees associated with SIR. The audit related fees for 2011 included fees associated with SIR's IPO. The tax fees charged by Ernst & Young LLP during 2012 and 2011 were for services involved in reviewing our tax reporting and tax compliance procedures related to our income tax returns for the fiscal years ended December 31, 2011 and 2010, respectively. Our 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 its independence and that its familiarity with our record keeping and accounting systems would permit it to provide these services with equal or higher quality, more quickly and at a lower cost than we could obtain these services from other providers.

        The affirmative vote of a majority of the votes cast will be necessary for the ratification of the appointment of Ernst & Young LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2013. The shareholder vote on proposal 3 is advisory and nonbinding and serves only as a recommendation to our Board.

        Our Board recommends you vote "FOR" the ratification of the appointment of Ernst & Young LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2013.

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SOLICITATION OF PROXIES

        Proxies may be solicited, without additional compensation, by our Trustees and officers, and by RMR and its directors, officers and employees, by mail, telephone or other electronic means or in person. We are paying the costs of this solicitation, including the preparation, printing, mailing and website hosting of proxy materials. We will request banks, brokers and other custodians, nominees and fiduciaries to forward proxy materials to the beneficial owners of our common shares and to obtain their voting instructions. We will reimburse those firms for their expenses. In addition, we have retained Innisfree to assist in the solicitation of proxies for a fee of $15,000 plus reimbursement of expenses. We have agreed to indemnify Innisfree against certain liabilities arising out of our agreement with Innisfree.

TRUSTEES AND EXECUTIVE OFFICERS

        The following are the ages and recent principal occupations, as of February 24, 2013, of our nominees, Trustees and executive officers. Unless otherwise specified, the business address of our nominees, Trustees and executive officers is c/o CommonWealth REIT, Two Newton Place, 255 Washington Street, Suite 300, Newton, Massachusetts 02458.

Independent Trustee Nominee for a Term Expiring in 2016

JOSEPH L. MOREA, Age: 57

        Mr. Morea has been one of our Independent Trustees since July 2012. Mr. Morea was a Vice Chairman and Managing Director, serving as head of U.S. Equity Markets, at RBC Capital Markets, an international investment bank, from 2003 until 2012. From 2008 to 2009, Mr. Morea also served as the head of U.S. Investment Banking for RBC Capital Markets. Previously, Mr. Morea was employed as an investment banker, including as a Managing Director and the co-head of U.S. Equity Capital Markets at UBS, Inc., the Chief Operating Officer and head of U.S. Equity Capital Markets at PaineWebber, Inc. and a Managing Director of Equity Capital Markets at Smith Barney, Inc. Prior to working as an investment banker, Mr. Morea was employed as a certified public accountant.

        Our Board concluded that Mr. Morea is qualified to serve as one of our Independent Trustees based upon, among other things, his experience in and knowledge of the investment banking industry, his demonstrated leadership and management abilities, his experience in capital raising and strategic business transactions, his professional training, skills and expertise in, among other things, finance matters and his qualifying as an Independent Trustee in accordance with the requirements of the NYSE, the SEC, our declaration of trust and our bylaws. Mr. Morea is an Independent Trustee in Group III and, if elected at the meeting, his term will expire at our 2016 annual meeting of shareholders.

Independent Trustees Continuing in Office

FREDERICK N. ZEYTOONJIAN, Age: 77

        Mr. Zeytoonjian has been one of our Independent Trustees since 1999. Mr. Zeytoonjian is the founder and has been Chairman and Chief Executive Officer of Turf Products, LLC, one of the largest distributors of lawn care equipment in the United States, for over 40 years. Mr. Zeytoonjian also has been an Independent Trustee of Senior Housing Properties Trust, or SNH, since 2003.

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        Our Board concluded that Mr. Zeytoonjian is qualified to serve as one of our Independent Trustees based upon, among other things, his demonstrated business leadership as a successful entrepreneur for decades, his work on public company boards and board committees, his experience in and knowledge of commercial real estate, his financial background and his institutional knowledge earned through service on our Board for 14 years and his qualifying as an Independent Trustee in accordance with the requirements of the NYSE, the SEC, our declaration of trust and our bylaws. Mr. Zeytoonjian is an Independent Trustee in Group I, and his term expires at our 2014 annual meeting of shareholders.

WILLIAM A. LAMKIN, Age: 53

        Mr. Lamkin has been one of our Independent Trustees since 2006. Mr. Lamkin has been a partner in Ackrell Capital LLC, a San Francisco based investment bank, since 2003. Previously, he was employed as a financial consultant and as an investment banker, including as a Senior Vice President in the investment banking division of ABN AMRO, Incorporated. Prior to working as a financial consultant and as an investment banker, Mr. Lamkin was a practicing attorney. Mr. Lamkin has served as an Independent Trustee of Hospitality Properties Trust, or HPT, and SIR, since 2007 and 2012, respectively.

        Our Board concluded that Mr. Lamkin is qualified to serve as one of our Independent Trustees based upon, among other things, his experience in and knowledge of the commercial real estate and investment banking industries, his work on and with public company boards and board committees, his demonstrated management ability, his experience in capital raising and strategic business transactions, his professional training, skills and expertise in, among other things, legal and finance matters, his institutional knowledge earned through service on our Board for seven years and his qualifying as an Independent Trustee in accordance with the requirements of the NYSE, the SEC, our declaration of trust and our bylaws. Mr. Lamkin is an Independent Trustee in Group II, and his term expires at our 2015 annual meeting of shareholders.

Managing Trustees Continuing in Office

BARRY M. PORTNOY, Age: 67

        Mr. Barry M. Portnoy has been one of our Managing Trustees since 1986. Mr. Portnoy has been a Managing Trustee of HPT, SNH, Government Properties Income Trust, or GOV, and SIR since 1995, 1999, 2009 and 2011, respectively. He has been a Managing Director of Five Star Quality Care, Inc., or Five Star, and of TravelCenters of America LLC, or TA, since 2001 and 2006, respectively. Mr. Portnoy is an owner of RMR and of RMR Advisors, Inc., or RMR Advisors, an SEC registered investment advisor. Mr. Portnoy has been an owner and a Director of RMR (and its predecessor) since its founding in 1986, a full time employee of RMR since 1997, the Chairman of RMR since 1998 and a Director and Vice President of RMR Advisors since 2002. Mr. Portnoy has been an Interested Trustee of RMR Real Estate Income Fund, or RIF, and its predecessor funds since shortly after their formation (the earliest of which was in 2002) and was an Interested Trustee of RMR Funds Series Trust from shortly after its formation in 2007 until its dissolution in 2009.⁽¹⁾ Mr. Portnoy practiced law for many years as a partner in, and chairman of, a law firm until 1997. Mr. Barry Portnoy is the father of Mr. Adam Portnoy, our other Managing Trustee and President.

   

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(1)

RIF, its predecessor funds and RMR Funds Series Trust are collectively referred to herein as the "RMR Funds."

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        Our Board concluded that Mr. Portnoy is qualified to serve as one of our Managing Trustees based upon, among other things, his demonstrated leadership capability, his extensive experience in and knowledge of the commercial real estate industry and real estate investment trusts, or REITs, his leadership position with RMR, his extensive public company director service, his professional skills and expertise in, among other things, legal and regulatory matters, his institutional knowledge earned through prior service on our Board and in key leadership positions with our manager and his qualifying as a Managing Trustee in accordance with the requirements of our declaration of trust and our bylaws. Mr. Barry Portnoy is a Managing Trustee in Group I, and his term expires at our 2014 annual meeting of shareholders.

ADAM D. PORTNOY, Age: 42

        Mr. Adam D. Portnoy has been one of our Managing Trustees since 2006 and our President since 2011. He also served as our Executive Vice President from 2003 through 2006. Mr. Portnoy has been a Managing Trustee of HPT, SNH, GOV and SIR, since 2007, 2007, 2009 and 2011, respectively. Mr. Portnoy has been an Interested Trustee of RIF and its predecessor funds since 2009. He was President of GOV from 2009 until 2011. Mr. Portnoy has been an executive officer of RMR since 2003 and currently is the President, Chief Executive Officer and a Director of RMR. Additionally, Mr. Portnoy is an owner of RMR and of RMR Advisors. Mr. Portnoy has been President and Director of RMR Advisors since 2007 and was a Vice President prior to that time since 2003. He has also been President of the RMR Funds since 2007. Prior to becoming President in 2007, Mr. Portnoy served as Vice President of the RMR Funds beginning in 2004. Prior to 2004, Mr. Portnoy held various positions in the finance industry and public sector, including working as an investment banker at Donaldson, Lufkin & Jenrette and ABN AMRO, working in private equity at the International Finance Corporation (a member of The World Bank Group) and DLJ Merchant Banking Partners, and serving as Chief Executive Officer of a telecommunications company. Mr. Portnoy is also currently a member of the Board of Governors of the National Association of Real Estate Trusts, a member of the Board of Trustees of Occidental College and serving as the Honorary Consul General of the Republic of Bulgaria to Massachusetts. Mr. Adam Portnoy is the son of Mr. Barry Portnoy, our other Managing Trustee.

        Our Board concluded that Mr. Portnoy is qualified to serve as one of our Managing Trustees based upon, among other things, his extensive experience in and knowledge of the commercial real estate industry and REITs, his leadership position with RMR, his public company director service, his demonstrated management ability, his experience in investment banking and private equity, his government organization service, his institutional knowledge earned through service on our Board for seven years and in key leadership positions with our manager for nine years and his qualifying as a Managing Trustee in accordance with the requirements of our declaration of trust and our bylaws. Mr. Adam Portnoy is a Managing Trustee in Group II, and his term expires at our 2015 annual meeting of shareholders.

Executive Officers

ADAM D. PORTNOY

        Mr. Portnoy has been our President since 2011, in addition to being one of our Managing Trustees and having other experience as described above.

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JOHN C. POPEO, Age: 52

        Mr. Popeo has been our Treasurer and Chief Financial Officer since 1999 and Assistant Secretary since 2008, and served as Secretary from 1999 to 2008. Mr. Popeo has also been Treasurer and Chief Financial Officer of SIR since its formation in 2011. Mr. Popeo has also been an Executive Vice President of RMR since 2008, and previously served as Treasurer of RMR from 1997 to 2012, as a Vice President from 1999 to 2006 and as a Senior Vice President from 2006 to 2008. Mr. Popeo served as Vice President of RMR Advisors from 2004 to 2009 and served as Vice President of the RMR Funds from shortly after their formation (the earliest of which was in 2002) until 2009. Mr. Popeo is a certified public accountant.

DAVID M. LEPORE, Age: 52

        Mr. Lepore has been our Chief Operating Officer since 2008 and Senior Vice President since 1998 and is primarily responsible for the operations of our properties. Mr. Lepore has also been a Senior Vice President of RMR since 2006 and was a Vice President and served in other capacities prior to that time. Mr. Lepore is a member of the Building Owners and Managers Association, the National Association of Industrial and Office Properties and is a certified real property administrator.

        Except as noted with regard to Mr. Barry Portnoy and Mr. Adam Portnoy, there are no family relationships among any of our Trustees or executive officers. Our executive officers serve at the discretion of our Board.

        RMR, RMR Advisors, GOV, HPT, SIR SNH, Five Star, TA and the RMR Funds may be considered to be affiliates of us. RMR is a privately owned company that provides management services to public and private companies, including us, GOV, HPT, SIR, SNH, Five Star and TA. GOV is a publicly traded REIT that primarily invests in properties that are majority leased to government tenants. HPT is a publicly traded REIT that primarily owns hotels and travel centers. SIR is a publicly traded REIT that primarily owns single tenant, net leased properties. SNH is a publicly traded REIT that primarily owns senior living properties and medical office buildings. Five Star is a publicly traded real estate based operating company in the healthcare and senior living services business. TA is a publicly traded real estate based operating company in the travel center business. The RMR Funds are or were investment companies registered under the Investment Company Act of 1940, as amended. RMR Advisors is an SEC registered investment adviser to the RMR Funds.

BOARD OF TRUSTEES

        Our business is conducted under the general direction of our Board as provided by our declaration of trust, our bylaws and the laws of the State of Maryland, the state in which we were organized on October 9, 1986.

        Three of our Trustees, William A. Lamkin, Joseph L. Morea and Frederick N. Zeytoonjian, are our Independent Trustees within the meaning of our declaration of trust and our bylaws. Two of our Trustees, Adam D. Portnoy and Barry M. Portnoy, are our Managing Trustees within the meaning of our bylaws.

        Our declaration of trust and our bylaws require that a majority of our Board be Independent Trustees. In determining the status of those Trustees who qualify as Independent Trustees, each year our Board affirmatively determines whether Trustees have a direct or indirect material relationship with

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us, including our subsidiaries, other than serving as our Trustees. When assessing a Trustee's relationship with us, our 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.

        Our Board has determined that Messrs. Lamkin, Morea and Zeytoonjian currently qualify as independent trustees under applicable NYSE rules and are Independent Trustees under our declaration of trust and our bylaws. In making these determinations, our Board considered each of these three Trustees' service in other enterprises and on the boards of other companies to which RMR and its affiliates provide management services. Our Board has concluded that none of these three Trustees possessed or currently possesses any relationship that could impair his judgment in connection with his duties and responsibilities as a Trustee or that could otherwise be a direct or indirect material relationship under applicable NYSE standards.

        During 2012, our Board held ten meetings, our Audit Committee held eight meetings, our Compensation Committee held five meetings and our Nominating and Governance Committee held three meetings. In addition, certain of our Trustees met four times as a special committee during 2012 to consider various matters. During 2012, each Trustee attended 75% or more of the total number of meetings of our Board and any committee of which he was a member during the time in which he served on our Board or such committee. All of our Trustees as of the date of the 2012 annual meeting of shareholders attended that meeting.

        Pursuant to our Governance Guidelines, our Independent Trustees meet at least once each year without management. The presiding Trustee at these meetings is the Chair of our Audit Committee, unless the Independent Trustees in attendance select another Independent Trustee to preside.

        We do not maintain directors' and officers' liability insurance for our Trustees and officers. Subject to certain limitations, our declaration of trust and separate indemnification agreements that we have entered into require that we indemnify our Trustees and officers.

Board Leadership Structure

        Our Board is comprised of both Independent Trustees and Managing Trustees, with a majority being Independent Trustees. Our Independent Trustees are not employees or affiliates, as such term is defined in our declaration of trust, of RMR, do not have a material business or professional relationship with RMR or any other person or entity that holds in excess of 9.8% of our issued and outstanding shares of beneficial interest, are not involved in our day to day activities, do not perform services for us except as Trustee and are persons who qualify as independent under our declaration of trust, our bylaws and the applicable rules of the NYSE and SEC. Our Managing Trustees are not Independent Trustees and have been employees of RMR or involved in our day to day activities for at least one year. Our Board is composed of three Independent Trustees and two Managing Trustees. Our President is a member of our Board. Our Treasurer is not a member of our Board, but he regularly attends Board meetings, as does our Director of Internal Audit. Other officers of RMR also sometimes attend Board meetings at the invitation of our Board.

        Our Audit, Compensation and Nominating and Governance Committees are comprised solely of our Independent Trustees, and an Independent Trustee serves as Chair of each such committee. These standing committees have responsibilities related to our leadership and governance, including among other things: (1) our Audit Committee reviews our financial reports, oversees our accounting and

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financial reporting processes, selects our independent accountants, determines the fees paid to our independent accountants and assists our Board with its oversight of our internal audit function, our risk management and our compliance with legal and regulatory requirements; (2) our Compensation Committee annually evaluates the performance of our Director of Internal Audit and approves the compensation we pay to him, determines any compensation that we directly pay to our President, reviews and approves any compensation that we directly pay to our Treasurer and any other senior executive of ours who is also a senior executive of RMR, reviews our business and property management agreements with RMR, evaluates RMR's performance under those agreements, approves the fees and certain other costs that we pay under those agreements, determines whether those agreements will be renewed, amended, terminated or allowed to expire and administers all of our equity compensation awards; and (3) our Nominating and Governance Committee considers nominees to serve on our Board, recommends to our Board nominees for election to our Board, assesses our Board's performance and reviews and assesses our Board leadership structure and Governance Guidelines and recommends to the Board any changes it determines appropriate. The Chairs of our Audit, Compensation and Nominating and Governance Committees set the agenda for their respective committee meetings, but committee members, our Managing Trustees or members of our management may suggest agenda items to be considered by these committees.

        We do not have a Chairman of our Board or a lead Independent Trustee. Our President, any Managing Trustee or any two Independent Trustees may call a special meeting. Our President and Managing Trustee and our other Managing Trustee, in consultation with our Treasurer, set the agenda for our Board meetings, and any Independent Trustee may place an item on an agenda by providing notice to our President and Managing Trustee, our other Managing Trustee or our Treasurer. Discussions at Board meetings are led by the Managing Trustee or Independent Trustee who is most knowledgeable on a subject. Our Board is small, which facilitates informal discussions and communication from management to the Board and among Trustees. Our Independent Trustees meet to consider Company business without the attendance of our Managing Trustees or our officers, and they meet separately with our officers, with our Director of Internal Audit and with our outside accountants. In such meetings of our Independent Trustees, the Chair of the Audit Committee presides unless the Independent Trustees determine otherwise.

        In light of the size of our Board and the oversight provided by and involvement of our Independent Trustees and Board committees in the leadership of our Company, our Board considers that our current leadership structure and conduct combines appropriate leadership with the ability to conduct our business efficiently and with appropriate care and attention.

Risk Oversight

        Our Board oversees risk as part of its general oversight of our Company, and 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 our Company is conducted by RMR, and RMR implements risk management in its activities. In discharging their oversight responsibilities, our Board and Board committees regularly review a wide range of reports provided to them by RMR and other service providers, including reports on market and industry conditions, operating and compliance reports, financial reports, reports on risk management activities, regulatory and legislative updates that may impact us, legal proceedings updates and reports on other business related matters, and discusses such matters among themselves and with representatives of RMR,

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counsel and our independent accountants. Our Audit Committee, which meets at least quarterly and reports its findings to our Board, performs a lead role in helping our Board fulfill its responsibilities for oversight of our financial reporting, internal audit function, risk management and our compliance with legal and regulatory requirements. Our Board and Audit Committee review periodic reports from our independent registered public accounting firm regarding potential risks, including risks related to our internal controls. Our Audit Committee also annually reviews, approves and oversees an internal audit plan developed by our Director of Internal Audit with the goal of helping our Company systematically evaluate the effectiveness of our risk management, control and governance processes, and periodically meets with our Director of Internal Audit to review the results of our internal audits, and directs or recommends to the Board actions or changes it determines appropriate to enhance or improve the effectiveness of our risk management. Our Compensation Committee also evaluates the performance of our Director of Internal Audit and RMR's performance under our business and property management agreements. Also, our Compensation Committee and our Board consider the fact that we have a share grant program that requires share grants to vest over a period of years, rather than a stock option program such as is employed by many other publicly owned companies. We believe that the use of share grants vesting over time rather than stock options mitigates the incentives for our management to undertake undue risks and encourages our management to make longer term, less risk prone decisions.

        While a number of risk management functions are performed, it is not possible to identify all of the risks that may affect us 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 our Company to bear certain risks to achieve our objectives. As a result of the foregoing and other factors, our Company's ability to manage risk is subject to substantial limitations.

BOARD COMMITTEES

        We have a standing Audit Committee, Compensation Committee and Nominating and Governance Committee, each of which has a written charter. Each of the above committees is currently comprised of Messrs. Lamkin, Morea and Zeytoonjian, who are independent under applicable NYSE listing standards, each committee's respective charter and, in the case of our Audit Committee, the applicable independence requirements of the SEC. Our Audit Committee, Compensation Committee and Nominating and Governance Committee are delegated the powers of our Board necessary to carry out their responsibilities.

        Our Audit Committee was established in accordance with Section 3(a)(58)(A) of the Exchange Act. The primary function of our Audit Committee is to assist our Board in fulfilling its responsibilities for oversight of: (1) the integrity of our financial statements; (2) our compliance with legal and regulatory requirements; (3) our independent registered public accounting firm's qualifications and independence; and (4) the performance of our internal audit function and independent registered public accounting firm. Our Board has determined that Mr. Lamkin is our Audit Committee financial expert and is "independent" as defined by the rules of the SEC and the NYSE. Our Board's determination that Mr. Lamkin is our Audit Committee financial expert was based upon: (i) his current position as partner of Ackrell Capital LLC, an investment banking firm and (ii) his prior experience (a) as a financial consultant; (b) as a Senior Vice President in the investment banking division of ABN AMRO, Incorporated; and (c) in various investment banking positions with Donaldson, Lufkin & Jenrette and PaineWebber and Kidder, Peabody, where his work included real estate investment banking and project lease financing matters. Under its charter, our Audit Committee has the final authority and responsibility to select our independent registered public accounting firm.

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        Our Compensation Committee's primary responsibilities include: (1) reviewing the terms of RMR's business management and property management agreements with us, evaluating the performance of RMR under those agreements, approving the fees and certain other costs that we are required to pay under those agreements and making determinations regarding continuance of or changes to those agreements; (2) evaluating the performance of our President and determining and approving any compensation, including any equity compensation, paid directly by us to our President; (3) evaluating the performance of our Director of Internal Audit and determining the compensation payable to him and the costs of our internal audit function generally; (4) evaluating, approving and administering all of our equity compensation plans; (5) evaluating whether our executive compensation programs encourage appropriate levels of risk taking by our executives; and (6) reviewing and considering the incentives and risks associated with our compensation policies and practices.

        The responsibilities of our Nominating and Governance Committee include: (1) identification of individuals qualified to become members of our Board and recommending to our Board the nominees for Trustee for each annual meeting of shareholders or when Board vacancies occur; (2) development and recommendation to our Board of governance guidelines; and (3) evaluation of the performance of our Board.

        The charter of each of our standing committees 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.

        Our policy with respect to Board members' attendance at our annual meetings of shareholders can be found in our Governance Guidelines, the full text of which appears at our website at www.cwhreit.com. In addition to our Governance Guidelines, copies of the charters of our Audit, Compensation and Nominating and Governance Committees, as well as our Code of Business Conduct and Ethics, may be obtained free of charge at our website, www.cwhreit.com, or by writing to our Secretary, CommonWealth REIT, Two Newton Place, 255 Washington Street, Suite 300, Newton, Massachusetts 02458.

COMMUNICATIONS WITH TRUSTEES

        Any shareholder or other interested person who desires to communicate with our Independent Trustees or any Trustees, individually or as a group, may do so by filling out a report at our website, www.cwhreit.com, by calling our toll-free confidential message system at (866) 511-5038 or by writing to the party for whom the communication is intended, c/o Director of Internal Audit, CommonWealth REIT, Two Newton Place, 255 Washington Street, Suite 300, Newton, Massachusetts 02458. Our Director of Internal Audit will then deliver any communication to the appropriate party or parties.

SELECTION OF CANDIDATES FOR TRUSTEES;
SHAREHOLDER RECOMMENDATIONS, NOMINATIONS AND OTHER PROPOSALS

        Our Board has established Governance Guidelines which, together with our declaration of trust and our bylaws, set forth the qualifications for service on our Board. Our Governance Guidelines may be changed from time to time by our Board upon the recommendation of our Nominating and Governance Committee. Our Board makes nominations of persons to be elected by shareholders as Trustees. Our Board also elects Trustees to fill Board vacancies that may occur from time to time. In

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both of these circumstances, our Board will act upon recommendations made by our Nominating and Governance Committee.

        In considering candidates to serve as Trustees, our Nominating and Governance Committee seeks individuals who have qualities that the Committee believes will be effective in serving our long term best interests. Among the characteristics that the Committee considers are the following: integrity, experience, achievements, judgment, intelligence, competence, personal character, ability to make independent analytical inquiries, willingness to devote adequate time to Board duties, likelihood that a candidate will be able to serve on our Board for an extended period and other matters that our Nominating and Governance Committee deems appropriate. While our Board does not have a specific diversity policy in connection with the selection of nominees for Trustee, due consideration is given to our Board's desire for an overall balance of diversity of perspectives, backgrounds and experiences. Our Board does not consider gender, sexual orientation, race, religion, ethnicity, national origin or citizenship to be relevant considerations and does not discriminate on the basis of such criteria. When considering candidates, our Nominating and Governance Committee will also assist our Board in determining the desired mix of experience, skills, attributes and other criteria that will strengthen our Board in a way that best serves the long term interests of our Company and complement the experience, skills, attributes and qualifications of existing Trustees. Depending on whether the position to be filled is that of an Independent Trustee or a Managing Trustee, the qualifications of the candidate to meet the criteria for each such category of Trustee is considered. In seeking candidates for Trustee who have not previously served as one of our Trustees, the Nominating and Governance Committee may use the business, professional and personal contacts of its members, it may accept recommendations from other Board members and, if it considers it appropriate, the Nominating and Governance Committee may engage a professional search firm. In addition to other criteria, our bylaws require that nominees submit any additional information required in connection with our license or regulation by state insurance authorities.

        In 2012, we did not pay any third party to identify or to assist in the evaluation of any candidate for election to our Board. We did not receive any shareholder recommendations or nominations for our Board for the 2013 annual meeting of shareholders, except the nomination made by our Board and recommendation by our Nominating and Governance Committee, each of which includes Board members who are shareholders of record.

        Shareholder Recommendations for Nominees.    A responsibility of our Nominating and Governance Committee is to consider candidates for election as Trustee who are properly recommended by shareholders. To be considered by our Nominating and Governance Committee, a shareholder recommendation for a nominee must be made by such shareholder's written notice to the Chair of our Nominating and Governance Committee and our Secretary, which notice should contain or be accompanied by the information and documents with respect to the recommended nominee and recommending shareholder that the recommending shareholder believes to be relevant or helpful to our Nominating and Governance Committee's deliberations. Our Nominating and Governance Committee may request additional information about the shareholder recommended nominee or about the shareholder recommending the nominee. Any recommended nominee will be considered by our Nominating and Governance Committee in its discretion using the same criteria as other candidates considered by it.

        The preceding paragraph applies only to shareholder recommendations for nominees to our Nominating and Governance Committee. A shareholder nomination must be made in accordance with

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the provisions of our bylaws, including the procedures discussed below, and applicable state and federal laws.

        2014 Annual Meeting Deadlines for Shareholder Proposals Pursuant to Rule 14a-8 under the Exchange Act.    Shareholder proposals intended to be presented pursuant to Rule 14a-8 under the Exchange Act at our 2014 annual meeting of shareholders must be received at our principal executive offices on or before October 28, 2013, in order to be considered for inclusion in our proxy statement for our 2014 annual meeting of shareholders, provided that if we hold our 2014 annual meeting on a date that is more than 30 days before or after May 14, 2014, shareholders must submit proposals for inclusion in our 2014 proxy statement within a reasonable time before we begin to print our proxy materials. Under Rule 14a-8, we are not required to include shareholder proposals in our proxy materials unless conditions specified in the rule are met.

        2014 Annual Meeting Deadlines for Shareholder Nominations and Shareholder Proposals Not Made Pursuant to Rule 14a-8 under the Exchange Act.    In order for one or more shareholders properly to propose a nominee for election to our Board or propose business outside of Rule 14a-8 under the Exchange Act, the shareholder(s) must comply in all respects with the advance notice and other provisions set forth in our bylaws, which currently include, among other things, requirements as to the shareholder's timely delivery of advance notice, share ownership and submission of specified information. For example, our bylaws provide that to nominate a Trustee for election to our Board at our annual meeting, the shareholder(s) must, among other things: (1) at the date such shareholder gives its advance notice, hold individually or in the aggregate at least 3% of our shares entitled to vote at the meeting on such election, must have held such shares continuously for at least three years and must continuously hold such shares through and including the time of the annual meeting (including any adjournment or postponement thereof); (2) be a shareholder of record at the time of giving notice through and including the time of the annual meeting (including any adjournment or postponement thereof); (3) be entitled to make nominations and to vote at the meeting on such election; (4) hold a certificate or certificates for all shares of beneficial interest of the Company owned by such shareholder during all times described in clause (1); and (5) comply with the advance notice procedures and requirements as to such nomination. The advance notice must set forth detailed specified information about the nominee and the nominee's affiliates and associates, the shareholder making the nomination and affiliates and associates of that shareholder and provide to the extent known by the shareholder giving the notice, the name and address of any other shareholder supporting the shareholder's nomination.

        As a further example, to propose other business to be considered by the shareholders at our annual meeting (other than the nomination of individuals for election to our Board), our bylaws provide that the shareholder must: (1) have continuously held at least $2,000 in market value, or 1% of our shares entitled to vote at the meeting on the proposal for such business for at least one year from the date the shareholder gives its advance notice and continuously hold such shares through and including the time of the annual meeting (including any adjournment or postponement thereof); (2) be a shareholder of record at the time of giving notice through and including the time of the annual meeting (including any adjournment or postponement thereof); (3) be entitled to propose such business and to vote at the meeting on the proposal for such business; (4) hold a certificate or certificates for all shares of beneficial interest of the Company owned by such shareholder during all times described in clause (1); and (5) comply with the advance notice procedures and requirements as to such business. The advance notice must set forth a description of such business, the reasons for proposing such

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business at the meeting and any material interest in such business of the shareholder, a description of all agreements, arrangements and understandings involving the shareholder in connection with the proposal of such business and a representation that the shareholder intends to appear in person or by proxy at the meeting to bring the business before the meeting.

        In addition, at the same time as the submission of a shareholder nomination or proposal for consideration at a meeting of our shareholders that, if elected or approved and implemented by us, would cause us to be in breach of any covenant in or in default under any debt instrument or agreement or other material agreement of ours or any subsidiary of ours, our bylaws provide that the shareholder must submit to our Secretary (i) evidence satisfactory to our Board of the lender's or contracting party's willingness to waive the breach of covenant or default, or (ii) a detailed plan for repayment of the applicable indebtedness or curing the contractual breach or default and satisfying any resulting damage, specifically identifying the actions to be taken or the source of funds, which plan must be satisfactory to our Board in its discretion, and evidence of the availability to us of substitute credit or contractual arrangements similar to the credit or contractual arrangements which are implicated by the shareholder nomination or other proposal that are at least as favorable to us, as determined by our Board in its discretion. Additionally, if (i) the submission of a shareholder nomination or proposal of other business to be considered at a shareholders meeting could not be considered or, if elected or approved, implemented by us without our or any subsidiary of ours, or the proponent shareholder, the nominee, the holder of proxies or their respective affiliates or associates filing with or otherwise notifying or obtaining the consent, approval or other action of any governmental or regulatory body, or a governmental action, or (ii) such shareholder's ownership of our shares or any solicitation of proxies or votes or holding or exercising proxies by such shareholder, the nominee or their respective affiliates or associates would require governmental action, then, at the same time as the submission of the shareholder nomination or proposal of other business, our bylaws provide that the proponent shareholder shall submit to our Secretary (x) evidence satisfactory to our Board that any and all governmental action has been given or obtained, including, without limitation, such evidence as our Board may require so that any nominee may be determined to satisfy any suitability or other requirements or (y) if such evidence was not obtainable from a governmental or regulatory body by such time despite the shareholder's diligent and best efforts, a detailed plan for making or obtaining the governmental action prior to the election of the nominee or the implementation of the proposal for other business, which plan must be satisfactory to our Board in its discretion.

        Our bylaws require that shareholder nominations and proposals intended to be made outside of Rule 14a-8 under the Exchange Act at our 2014 annual meeting of shareholders must be submitted, in accordance with the requirements of our bylaws, not later than 5:00 p.m. Eastern Time on October 28, 2013 (which is also the date, after which, shareholder nominations and proposals made outside of Rule 14a-8 under the Exchange Act would be considered "untimely" within the meaning of Rule 14a-4(c) under the Exchange Act) and not earlier than September 28, 2013; provided, that, if our 2014 annual meeting is called for a date that is more than 30 days earlier or later than May 14, 2014, 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 (1) notice of the date of our 2014 annual meeting is mailed or otherwise made available or (2) public announcement of the date of our 2014 annual meeting is first made by us.

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        The foregoing description of the procedures for a shareholder to propose a nomination for election to our Board or other business for consideration at an annual meeting is only a summary and is not a complete listing of all requirements. Copies of our bylaws, including the provisions that concern shareholder recommendations and the requirements for shareholder nominations and other proposals, may be obtained by writing to our Secretary at CommonWealth REIT, Two Newton Place, 255 Washington Street, Suite 300, Newton, Massachusetts 02458, or from the SEC's website at www.sec.gov. Any shareholder considering making a nomination or other proposal should carefully review and comply with those provisions. Under our declaration of trust and our bylaws, a shareholder is obligated to indemnify us for costs and expenses we incur arising from the shareholder's breach or failure to fully comply with any covenant, condition or provision of our declaration of trust or our bylaws, including costs and expenses we may incur as a result of the shareholder's failure to comply with the requirements to make nominations and proposals.

COMPENSATION DISCUSSION AND ANALYSIS

Compensation Overview

        We do not have any employees. None of our executive officers has an employment agreement with us or any agreement that becomes effective upon his termination or a change in control of us. Our manager, RMR, provides services that otherwise would be provided by employees. RMR conducts our day to day operations on our behalf and compensates our named executive officers, Messrs. Adam Portnoy, John Popeo and David Lepore, directly and in its sole discretion in connection with their services rendered to RMR and to us. We do not pay our executive officers salaries or bonuses or provide other compensatory benefits except for the grants of shares under our share award plan discussed below. Although our Compensation Committee reviews and approves our business management and property management agreements with RMR, it is not involved in compensation decisions made by RMR for its employees other than the employee serving as our Director of Internal Audit. Our payments to RMR are described in Related Person Transactions and Company Review of Such Transactions in this proxy statement.

        In September 2012, the Chair of our Compensation Committee met with our Managing Trustees and the chairs of the compensation committees of the other public REITs, RIF and the operating companies for which RMR and its affiliates provide management services. RMR provides management services to: (1) GOV, a publicly traded REIT that primarily invests in properties that are majority leased to government tenants; (2) HPT, a publicly traded REIT that primarily owns hotels and travel centers; (3) SIR, a publicly traded REIT that primarily owns single tenant, net leased properties; (4) SNH, a publicly traded REIT that primarily owns senior living properties and medical office buildings; (5) Five Star, a publicly traded real estate based operating company in the healthcare and senior living services business; and (6) TA, a publicly traded real estate based operating company in the travel center business. The purpose of this meeting was, among other things, to discuss compensation philosophy and factors that may affect compensation decisions, to consider the compensation payable to our Director of Internal Audit who provides services to us and to other companies managed by RMR and its affiliates, to consider the allocation of internal audit and related services costs among us and other companies to which RMR or its affiliates provide internal audit and related services, to provide a comparative understanding of potential share grants by us and the other affected companies and to hear and consider recommendations from our Managing Trustees concerning potential share grants. The share grants made by the companies and other REITs managed by RMR and its affiliates

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are considered to be appropriately comparable because of the similarities between certain services we require from our share grantees and the services provided to these other companies. Subsequent to this meeting, the members of our Compensation Committee held a meeting at which the Chair provided a report of the information discussed with the Managing Trustees and others, and made recommendations for share grants to our executive officers. Our Compensation Committee then discussed these recommendations and other factors, including the following factors for the 2012 share grants: (1) the value of the proposed share grants; (2) the historical awards previously granted to each executive officer and the corresponding values at the time of the grants; (3) the recommendations by RMR as presented by our Managing Trustees; (4) the value of share grants to executive officers providing comparable services at other REITs and companies managed by RMR; (5) changes, if any, in the responsibilities assigned to, or assumed by, each executive officer during the past year and on a going forward basis; (6) the length of historical services to us by each executive officer; (7) the responsibilities of each executive officer and the Compensation Committee's perception regarding the quality of the services provided by each executive officer in carrying out those responsibilities; and (8) our financial and operating performance in the past year and our perceived future prospects. Our Compensation Committee's starting premise each year is to award our named executive officers the same number of shares as they were awarded in the prior year in an effort to meet recipients' expectations. Our Compensation Committee then considered these multiple factors in determining whether to increase or decrease the amounts of the prior year's grants. There was no formulaic approach to the use of these various factors in determining the number of shares to award to each executive officer. The share amounts were determined on a subjective basis using the various factors at our Compensation Committee's sole discretion. Our executive officers (other than Mr. Adam Portnoy) did not participate in these meetings and were not involved in determining or recommending the amount or form of executive compensation they receive from us. Our President, Mr. Adam Portnoy, in his capacity as our Managing Trustee and as president of RMR, participated in these meetings and in share grant recommendations. Our Compensation Committee did not engage a compensation consultant to participate in the determination or recommendation of the amount or form of executive compensation.

        In evaluating our compensation process for 2012, our Compensation Committee generally considered the results of the advisory vote of our shareholders on the compensation of the executive officers named in our proxy statement for our 2012 annual meeting of shareholders. Our Compensation Committee noted that 95% of votes cast approved of the compensation of those executive officers as described in our 2012 proxy statement. Our Compensation Committee considered these voting results as supportive of the Committee's general executive compensation practices.

Analysis of Grants under Our Share Award Plan

        Although we do not pay any cash compensation directly to our officers and have no employees, we have adopted a share award plan to reward our executive officers and other RMR employees who provide services to us and to foster a continuing identity of interest between them and our shareholders. We award shares under our share award plan to recognize our executive officers' scope of responsibilities, reward demonstrated performance and leadership, motivate future performance, align the interests of our executives with those of our other shareholders and motivate the executives to remain employees of our manager and to continue to provide services to us through the term of the awards.

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        Under its charter, our Compensation Committee evaluates, approves and administers our equity compensation plans, which currently consist solely of our share award plan providing for the grants of our common shares. The Compensation Committee has historically determined to use grants of restricted common shares rather than stock options as equity compensation. Because the value of our 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, we believe a conventional stock option plan might not provide appropriate incentives for management for a business like ours, but a share grant plan may create a better identity of interests between management and other shareholders. Also, because we believe a stock option plan may encourage excessive short term risk taking, we have historically granted restricted shares rather than stock options.

        Our Compensation Committee uses comparative information about other REITs managed by RMR as additional data to help it determine whether it is awarding share amounts that it deems reasonable based on the characteristics of those REITs and their respective officers. The Compensation Committee also considers the size and structure of the other REITs and other RMR managed businesses, and the experience, length of service and scope of duties and responsibilities of the officers at these other companies to assess the value of the share awards proposed for our officers in light of the proposed awards for officers with comparable roles at the other companies. Our Compensation Committee reviewed the data regarding the other REITs and their officers to help it gauge the reasonableness of the recommended 2012 awards 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 or assign weight to any particular characteristic of these other companies or their officers because our Compensation Committee determines the share amounts in its sole discretion on a non-formulaic basis. In 2012, the Compensation Committee considered the foregoing factors and decided to award 7,500 shares to each of our President and Chief Financial Officer and 3,750 shares to our Chief Operating Officer, in accordance with the recommendation of our Managing Trustees.

        We determine the fair market value of the shares granted based on the closing price of our 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 and to continue to provide services to us. 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 us and to the recipients. In the event a recipient granted a share award ceases to perform duties for us or ceases to be an officer or an employee of RMR or any company that RMR manages during the vesting period, we may cause forfeiture of, or we 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 our share award plan are entitled to receive distributions that we make on our common shares.

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

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        We believe that our compensation philosophy and programs are designed to foster a business culture that aligns the interests of our executive officers with those of our shareholders. We believe that the equity compensation of our executive officers is appropriate to the goal of providing shareholders dependable, long term returns.

COMPENSATION COMMITTEE REPORT

        The undersigned members of the Compensation Committee have reviewed and discussed the Compensation Discussion and Analysis with our management. Based upon this review and discussion, the Compensation Committee recommended to the Board that the Compensation Discussion and Analysis be included in this proxy statement and incorporated by reference into our Annual Report on Form 10-K for the year ended December 31, 2012.

                        COMPENSATION COMMITTEE
                        Frederick N. Zeytoonjian, Chairman
                        William A. Lamkin
                        Joseph L. Morea

COMPENSATION TABLES

        The following tables provide: (1) summary 2012, 2011 and 2010 compensation information relating to our named executive officers; (2) information with respect to share awards made to, or held by, our named executive officers during the periods or at the dates specified below; and (3) compensation information relating to our Trustees for 2012. Our named executive officers consist of three individuals, our President, our Treasurer and Chief Financial Officer and our Chief Operating Officer and Senior Vice President, the compensation of whom is required to be reported in this proxy statement under the rules of the SEC. None of our named executive officers are employed by us. Our manager, RMR, provides services that otherwise would be provided by employees and compensates our named executive officers directly and in RMR's sole discretion in connection with their services rendered to RMR and to us. We do not pay our executive officers salaries or bonuses or provide other compensatory benefits except for the grants of shares under our share award plan.

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SUMMARY COMPENSATION TABLE FOR 2012, 2011 AND 2010

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(1)

Represents the grant date fair value of shares granted in 2012, 2011 and 2010, as applicable, compiled in accordance with FASB Accounting Standards Codification Topic 718, "Compensation—Stock Compensation," or ASC 718. No assumptions are used in this calculation.

(2)

Consists of distributions in each year on unvested shares.

(3)

Mr. Adam Portnoy was appointed our President on January 10, 2011. Mr. Portnoy's compensation for 2012 and 2011 attributable to his services as a Managing Trustee, which consisted of a share award with a value of $37,480 and $53,140, respectively, is included above, and his 2012 compensation for his services as a Managing Trustee is also included in the Trustee Compensation for 2012 table below.

GRANTS OF PLAN BASED AWARDS FOR 2012
(Shares granted in 2012, including vested and unvested grants)

        Share awards granted by us to our executive officers in 2012 provide that one fifth of each award vests on the grant date and one fifth vests on each of the next four anniversaries of the grant date. In the event a recipient granted a share award ceases to perform duties for us or ceases to be an officer or an employee of RMR or any company that RMR manages during the vesting period, at our option, the recipient shall forfeit or we may repurchase the common shares that have not yet vested for

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nominal consideration. Holders of vested and unvested shares awarded under our share award plan are eligible to receive distributions that we make on our shares on the same terms as other holders of our common shares.

OUTSTANDING EQUITY AWARDS AT FISCAL YEAR END FOR 2012
(Shares granted in 2012 and prior years, which have not yet vested)

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STOCK VESTED FOR 2012
(Share grants that vested in 2012, including shares granted in prior years)

POTENTIAL PAYMENTS UPON TERMINATION OR CHANGE IN CONTROL

        From time to time, we have entered into arrangements with former employees of RMR in connection with the termination of their employment with RMR, providing for the acceleration of vesting of restricted shares previously granted to them under our share award plan. Although we have no formal policy, plan or arrangement for payments to employees of RMR in connection with their termination of employment with RMR, 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 the Company's best interests to do so.

TRUSTEE COMPENSATION FOR 2012
(2012 compensation; all share grants to Trustees vest at the time of grant)

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        Each Independent Trustee receives an annual fee of $35,000 for services as a Trustee, plus a fee of $750 for each meeting attended. Up to two $750 fees are paid if a Board meeting and one or more Board committee meetings are held on the same date. The chairpersons of our Audit Committee, Compensation Committee and Nominating and Governance Committee receive an additional $10,000, $5,000 and $5,000, respectively, each year. Under our Governance Guidelines, each Trustee is required to maintain the necessary level of expertise to perform his or her responsibilities as Trustee and we reimburse each Trustee for the out of pocket costs he or she incurs from attending continuing education programs. In addition, each Trustee received a grant of 2,000 of our common shares in 2012. We generally reimburse all our Trustees for travel expenses incurred in connection with their duties as Trustees.

        Our Board believes it is important to align the interests of Trustees with those of our shareholders and for Trustees to hold equity ownership positions in our Company. Accordingly, our Board believes that a portion of each Trustee's compensation should be paid in shares. In determining the amount and composition of such compensation, our Board considers the compensation of trustees and directors of other comparable enterprises, both with respect to size and industry, including the compensation of trustees and directors of other companies managed by RMR.

        In 2012, our Board reviewed the compensation paid to our Trustees and determined both the amount of such compensation and the allocation of such compensation between equity based awards and cash. Our Managing Trustees do not receive any cash compensation for their services as Trustees, but they do receive common share grants equal to the share grants awarded to our Independent Trustees.

AUDIT COMMITTEE REPORT

        In the course of our oversight of the Company's financial reporting process, we have: (1) reviewed and discussed with management the audited financial statements for the year ended December 31, 2012; (2) discussed with Ernst & Young LLP, the Company's independent registered public accounting firm, the matters required to be discussed by the Statement on Auditing Standards No. 61, as amended (AICPA, Professional Standards, Vol. 1, AU section 380), as adopted by the Public Company Accounting Oversight Board in Rule 3200T; (3) received the written disclosures and the letter from the independent registered public accounting firm required by applicable requirements of the Public Company Accounting Oversight Board regarding the independent accountant's communications with the audit committee concerning independence; (4) discussed with the independent registered public accounting firm its independence; and (5) considered whether the provision of non-audit services by the independent registered public accounting firm is compatible with maintaining its 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 Company's Annual Report on Form 10-K for the year ended December 31, 2012, for filing with the SEC.

                        AUDIT COMMITTEE
                        William A. Lamkin, Chairman
                        Joseph L. Morea
                        Frederick N. Zeytoonjian

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SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT

        Unless otherwise indicated, the information set forth below is as of February 19, 2013. The following table sets forth information regarding the beneficial ownership of our common shares (excluding any fractional shares that may be beneficially owned by such persons) by: (1) each person or entity known to us to be the beneficial owner of more than 5% of our outstanding common shares; (2) each of our Trustees, nominees and the persons listed in the Compensation Tables in this proxy statement; and (3) our Trustees and executive officers as a group. Unless otherwise indicated, we believe that each owner named below has sole voting and investment power for all our common shares shown to be beneficially owned by that person or entity. As of the date first set forth in this paragraph, we do not know of any outstanding rights to acquire our shares of the type specified in Rule 13d-3(d)(1) under the Exchange Act.

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RELATED PERSON TRANSACTIONS AND COMPANY REVIEW OF SUCH TRANSACTIONS

        We have adopted written Governance Guidelines that address the consideration and approval of any related person transactions. Under these Governance Guidelines, we may not enter into any transaction in which any Trustee or executive officer, any member of the immediate family of any Trustee or executive officer or any other related person, has or will have a direct or indirect material interest unless that transaction has been disclosed or made known to our Board and our 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 and approved or ratified by both (1) the affirmative vote of a majority of our entire Board and (2) the affirmative vote of a majority of our Independent Trustees. The Governance Guidelines further provide that, in determining whether to approve or ratify a transaction, our Board, or disinterested Trustees or Independent Trustees, as the case may be, shall act in accordance with any applicable provisions of our declaration of trust, consider all of the relevant facts and circumstances and approve only those transactions that are fair and reasonable to us. All related person transactions described below were reviewed and approved or ratified by a majority of the disinterested Trustees or otherwise in accordance with our policies described above. In the case of transactions with us by RMR employees (other than our Trustees and executive officers) subject to our Code of Business Conduct and Ethics, the employee must seek approval from an executive officer who has no interest in the matter for which approval is being requested.

        We have no employees. Personnel and various services we require to operate our business are provided to us by RMR. We have two agreements with RMR to provide management and administrative services to us: (1) a business management agreement, which relates to our business generally, and (2) a property management agreement, which relates to our property level operations. RMR also provides management and administrative services to SIR under separate business management and property management agreements with SIR.

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        RMR has approximately 820 employees. One of our Managing Trustees, Mr. Barry Portnoy, is Chairman, majority owner and an employee of RMR. Our other Managing Trustee, Mr. Adam Portnoy, who is also our President, is the son of Mr. Barry Portnoy, and an owner, President, Chief Executive Officer and a director of RMR. Each of our other executive officers is also an officer of RMR. SNH's, GOV's and SIR's executive officers are officers of RMR, and SNH's President and Chief Operating Officer is also a director of RMR. A majority of our Independent Trustees also serve as independent directors or independent trustees of other public companies to which RMR provides management services. Mr. Barry Portnoy serves as a managing director or managing trustee of those companies, including SNH, GOV and SIR, and Mr. Adam Portnoy serves as a managing trustee of a majority of those companies, including SNH, GOV and SIR. In addition, officers of RMR serve as officers of those companies. We understand that further information regarding those relationships is provided in the applicable periodic reports and proxy statements filed by those other companies with the SEC.

        Our Board has given our Compensation Committee, which is comprised exclusively of our Independent Trustees, authority to act on our behalf with respect to our management agreements with RMR. The charter of our Compensation Committee requires the Committee annually to review the terms of these agreements, evaluate RMR's performance under the agreements and renew, amend, terminate or allow to expire the management agreements.

        Our business management agreement with RMR provides for payment to RMR of a business management fee at an annual rate equal to (a) 0.7% of the historical cost of our real estate investments, as described in the business management agreement, located in the United States, Puerto Rico or Canada, for the first $250.0 million of such investments, and 0.5% thereafter, plus (b) 1.0% of the historical cost of our real estate investments located outside the United States, Puerto Rico and Canada. In addition, RMR receives an incentive fee equal to 15% of the product of (i) the weighted average of our common shares outstanding on a fully diluted basis during a fiscal year and (ii) the excess, if any, of the FFO Per Share, as defined in the business management agreement, for such fiscal year over the FFO Per Share for the preceding fiscal year. The incentive fee is paid in our common shares and in any year shall not exceed $0.04 multiplied by the weighted average number of our common shares outstanding on a fully diluted basis during such fiscal year. Our common shares for these purposes are valued at the average closing prices of our common shares as reported on the NYSE during the month of December of the fiscal year to which the incentive fee pertains. Our investments in GOV and SIR, which are described below, are not counted for purposes of determining the business management fees payable by us to RMR. In determining the business management fee payable by us to RMR under the business management agreement, the historical cost of any assets we acquire from another REIT to which RMR provides business management or property management services, or an RMR Managed REIT, will be the applicable selling RMR Managed REIT's historical costs for those properties, determined in the manner specified in our business management agreement, rather than our acquisition costs for those properties. In such an acquisition, the business management fee we pay to RMR in respect of the acquired properties would be expected to correspond to the reduction in the similar business management fee that the selling RMR Managed REIT pays to RMR, such that RMR would not be expected to receive an increase in the business management fees payable in aggregate by us and the selling RMR Managed REIT in respect of the acquired properties. The business management agreement also provides that, with certain exceptions, if we determine to offer for sale or other disposition any real property that, at such time, is of a type within the investment focus of another RMR Managed REIT, we will first offer that property for purchase or disposition to that RMR Managed REIT and negotiate in good faith for such purchase or disposition. Pursuant to

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our business management agreement with RMR and the business management agreement between SIR and RMR, the business management fees we and SIR paid to RMR on a consolidated basis were $43.6 million for 2012. No incentive fee was payable to RMR for 2012.

        Our property management agreement with RMR provides for management fees equal to 3.0% of gross collected rents and construction supervision fees equal to 5.0% of construction costs. In connection with our property management agreement with RMR and the property management agreement between SIR and RMR, the aggregate property management and construction supervision fees we and SIR paid to RMR on a consolidated basis were $33.7 million for 2012.

        With respect to our investments in Australia, RMR has agreed to waive half of the fees payable by us under the property management agreement and half of the business management fees related to real estate investments located outside of the United States, Puerto Rico and Canada, so long as our business and property management agreement with MacarthurCook Fund Management Limited, or MacarthurCook, with respect to those investments is in effect and we or any of our subsidiaries are paying fees under that agreement. MacarthurCook earned $1.8 million in 2012 with respect to our Australian properties, which amount is equal to the fees waived by RMR and excluded from the amounts that were payable to RMR during 2012. Our contract with MacarthurCook terminated on January 31, 2013, and on that date we entered into a business and property management agreement, or the Australia Management Agreement, with RMR Australia Asset Management Pty Limited, or RMR Australia, for the benefit of CWH Australia Trust (formerly the MacarthurCook Industrial Property Fund), a subsidiary of ours, or CWHAT. The terms of the Australia Management Agreement are substantially similar to the terms of the management agreement we had with MacarthurCook. RMR Australia is owned by our Managing Trustees and it has been granted an Australian financial services license by the Australian Securities & Investments Commission. The Australia Management Agreement provides for compensation to RMR Australia for business management and real estate investment services at an annual rate equal to 0.5% of the average historical cost, including the cost of capital improvements, of CWHAT's real estate investments, as described in the Australia Management Agreement. The Australia Management Agreement also provides for additional compensation to RMR Australia for property management services at an annual rate equal to 50% of the difference between 3.0% of collected gross rents, including reimbursed operating expenses and taxes, and the aggregate of all amounts paid or payable by or on behalf of CWHAT to third party property managers. Additionally, the Australia Management Agreement provides for further compensation to RMR Australia for construction supervision services at an annual rate equal to 50% of the difference between 5.0% of constructions costs and any amounts paid to third parties for construction management and/or supervision. Similar to our prior arrangement with respect to fees we paid to MacarthurCook, RMR has agreed to waive half of the fees payable by us under our property management agreement with RMR and half of the business management fees otherwise payable by us under our business management agreement with RMR related to real estate investments that are subject to the Australia Management Agreement for so long as the Australia Management Agreement is in effect and we or any of our subsidiaries are paying the fees under that agreement. The Australia Management Agreement was approved by our Compensation Committee, which is composed solely of Independent Trustees.

        RMR also provides internal audit services to us in return for our share of the total internal audit costs incurred by RMR for us and other publicly owned companies managed by RMR and its affiliates, which amounts are subject to approval by our Compensation Committee. Our Audit Committee

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appoints our Director of Internal Audit. Our and SIR's share of RMR's costs of providing this internal audit function was, on a consolidated basis, approximately $0.4 million for 2012. These allocated costs are in addition to the business and property management fees we and SIR paid to RMR.

        We are generally responsible for all of our operating expenses, including certain expenses incurred by RMR on our behalf. We are not responsible for payment of RMR's employment, office or administration expenses incurred to provide management services to us, except for the employment and related expenses of RMR employees who provide on-site property management services and our pro rata share of the staff employed by RMR who perform our internal audit function. Pursuant to our business management agreement, RMR may from time to time negotiate on our behalf with certain third party vendors and suppliers for the procurement of services to us. As part of this arrangement, we may enter agreements with RMR and other companies to which RMR provides management services for the purpose of obtaining more favorable terms from such vendors and suppliers.

        Both our business management agreement with RMR and our property management agreement with RMR automatically renew for successive one year terms unless we or RMR give notice of non-renewal before the end of an applicable term. We or RMR may terminate either agreement upon 60 days' prior written notice, and RMR may also terminate the property management agreement upon five business days' notice if we undergo a change of control, as defined in the property management agreement. On December 11, 2012, we entered amendments to these agreements, which extended the term of the business management agreement until December 31, 2013, clarified certain currently existing policies in the business management agreement and changed certain procedures for the arbitration of disputes pursuant to these agreements.

        Under our business management agreement with RMR, we acknowledge that RMR also provides management services to other companies, which include SNH, GOV and SIR, and will not be required to present us with opportunities to invest in properties that are primarily of a type that are within the investment focus of another business now or in the future managed by RMR and that, in the event of conflict between us and any such other company, RMR shall in its discretion determine on which party's behalf it shall act.

        RMR also leases from us approximately 34,100 square feet of office space for eleven of its regional offices. We earned approximately $0.6 million in rental income from RMR in 2012, which we believe was commercially reasonable rent for this office space, not all of which was leased to RMR for the entire period.

        Under our share award plan, we typically grant restricted shares to certain employees of RMR, some of whom are our officers. In 2012, we granted a total of 71,617 restricted shares with an aggregate value of $1.1 million to such persons, based upon the closing price of our common shares on the NYSE on the date of grant. One fifth of those restricted shares vested on the grant date and one fifth vests on each of the next four anniversaries of the grant date. These share grants to RMR employees are in addition to the fees we pay to RMR. On occasion, we have entered into arrangements with former employees of RMR in connection with the termination of their employment with RMR, providing for the acceleration of vesting of restricted shares previously granted to them under our share award plan.

        SNH was formerly our 100% owned subsidiary. It was spun off to our shareholders in 1999. As of the date of this report, SNH owns 250,000 of our common shares. Our two Managing Trustees, Mr. Barry Portnoy and Mr. Adam Portnoy, are also managing trustees of SNH. In addition, one of our

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Independent Trustees, Mr. Frederick Zeytoonjian, is also an independent trustee of SNH. RMR provides management services to both us and SNH.

        At the time of SNH's spin off, we and SNH entered into a transaction agreement pursuant to which, among other things, we and SNH agreed that so long as we own 10% or more of SNH's common shares, we and SNH engage the same manager or we and SNH have any common managing trustees: (1) we will not make any investment in senior apartments, congregate communities, assisted living properties, nursing homes or other healthcare properties, but excluding medical office properties, medical clinics and clinical laboratory buildings, without the prior approval of a majority of SNH's independent trustees, and (2) SNH will not make any investment in office buildings, warehouses or malls, including medical office properties and clinical laboratory buildings without the prior approval of a majority of our Independent Trustees. We and SNH subsequently agreed to permit SNH, rather than us, to invest in medical office, clinic and biomedical, pharmaceutical and laboratory buildings.

        GOV was formerly our 100% owned subsidiary. We are GOV's largest shareholder and, as of the date of this report, we own 9,950,000 common shares of GOV, which represents approximately 18.2% of GOV's outstanding common shares. Our two Managing Trustees, Mr. Barry Portnoy and Mr. Adam Portnoy, are also managing trustees of GOV, and our President, Mr. Adam Portnoy, was the President of GOV from its formation in 2009 until January 2011. RMR provides management services to both us and GOV.

        In June 2009, GOV completed an IPO pursuant to which GOV ceased to be a majority owned subsidiary of ours. In connection with this offering, we and GOV entered into a transaction agreement that governs our separation from and relationship with GOV. Pursuant to this transaction agreement, among other things, we and GOV agreed that, so long as we own in excess of 10% of GOV's outstanding common shares, we and GOV engage the same manager or we and GOV have any common managing trustees: (1) we will not acquire ownership of properties that are majority leased to government tenants, unless a majority of GOV's independent trustees who are not also our Trustees have determined not to make the acquisition; (2) GOV will not acquire ownership of office or industrial properties that are not majority leased to government tenants, unless a majority of our Independent Trustees who are not also GOV's trustees have determined not to make the acquisition; and (3) GOV will have a right of first refusal to acquire any property owned by us that we determine to divest if the property is then majority leased to a government tenant, which right of first refusal will also apply in the event of an indirect sale of any such properties resulting from a change of control of us. The provisions described in (1) and (2) do not prevent GOV from continuing to own and lease its current properties or properties otherwise acquired by GOV that cease to be majority leased to government tenants following the termination of government tenancies; and, similarly, the provisions described in (1) and (2) also do not prohibit us from leasing our current or future properties to government tenants. We and GOV also agreed that disputes arising under the transaction agreement may be resolved by binding arbitration.

        SIR was formerly our 100% owned subsidiary. We are SIR's largest shareholder and SIR continues to be one of our consolidated subsidiaries. As of the date of this report, we own 22,000,000 common shares of SIR, which represents approximately 56.0% of SIR's outstanding common shares. Our two Managing Trustees, Mr. Barry Portnoy and Mr. Adam Portnoy, are also managing trustees of SIR, and Mr. John Popeo, our Treasurer and Chief Financial Officer, also serves as the treasurer and chief financial officer of SIR. In addition, one of our Independent Trustees, Mr. William Lamkin, is an independent trustee of SIR.

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        In December 2011, SIR filed a registration statement with the SEC for an IPO, of common shares as a REIT that is focused on owning and investing in net leased, single tenant properties. On February 16, 2012, we transferred 251 properties (approximately 21.4 million square feet) to SIR, including substantially all of our commercial and industrial properties located in Oahu, Hawaii and 23 suburban office and industrial properties located throughout the mainland U.S. In exchange for our contribution of 251 properties to SIR, we received 22,000,000 SIR common shares and a $400.0 million demand promissory note, or the Demand Note. On March 12, 2012, SIR completed its IPO, or the SIR IPO, in which it issued 9,200,000 of its common shares (including 1,200,000 common shares sold pursuant to the underwriters' over allotment option) for net proceeds (after deducting underwriters' discounts and commissions and estimated expenses) of $180.8 million. SIR applied those net proceeds, along with proceeds from drawings under SIR's $500.0 million revolving credit facility, to repay in full the Demand Note. SIR also reimbursed us for costs that we incurred in connection with SIR's organization and preparation for the SIR IPO.

        In connection with the SIR IPO, we and SIR entered into a transaction agreement that governs our separation from and relationship with SIR. The transaction agreement provides that, among other things, (1) the current assets and liabilities of the 251 properties that we transferred to SIR, as of the time of closing of the SIR IPO, were settled between us and SIR so that we will retain all pre-closing current assets and liabilities and SIR will assume all post-closing current assets and liabilities and (2) SIR will indemnify us with respect to any liability relating to any property transferred by us to SIR, including any liability which relates to periods prior to SIR's formation, other than the pre-closing current assets and current liabilities that we retained with respect to the 251 transferred properties.

        We (excluding SIR), RMR, SNH, GOV, SIR and three other companies to which RMR provides management services each currently own 12.5% of Affiliates Insurance Company, or AIC, an Indiana insurance company. All of our Trustees, all of the trustees and directors of the other publicly held AIC shareholders and nearly all of the directors of RMR currently serve on the board of directors of AIC. RMR provides management and administrative services to AIC pursuant to a management and administrative services agreement with AIC. Our Governance Guidelines provide that any material transaction between us and AIC shall be reviewed, authorized and approved or ratified by the affirmative votes of both a majority of our entire Board and a majority of our Independent Trustees. The shareholders agreement among us, the other shareholders of AIC and AIC includes arbitration provisions for the resolution of disputes.

        As of the date of this proxy statement, we and SIR collectively have invested $10.5 million in AIC since its formation in November 2008. SIR became a shareholder of AIC during the quarter ended June 30, 2012. For 2012, we and SIR recognized on a consolidated basis $0.6 million related to our investment in AIC. We and the other shareholders of AIC have purchased property insurance providing $500.0 million of coverage pursuant to an insurance program arranged by AIC and with respect to which AIC is a reinsurer of certain coverage amounts. This program was modified and extended in June 2012 for a one year term, and we paid a premium, including taxes and fees, of $6.6 million in connection with that renewal, which amount is the consolidated premium paid by us and SIR and which amount may be adjusted from time to time as we or SIR acquire or dispose of properties that are included in this program. We are also currently investigating the possibilities to expand our insurance relationships with AIC to include other types of insurance. We and SIR may invest additional amounts in AIC in the future if the expansion of this insurance business requires additional capital, but we are not obligated to do so. By participating in this insurance business with RMR and the other

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companies to which RMR provides management services, we expect that we may benefit financially by possibly reducing our insurance expenses or by realizing our pro rata share of any profits of this insurance business.

        The foregoing descriptions of our agreements with RMR, SNH, GOV, SIR and AIC 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 our annual report to shareholders and our Annual Report on Form 10-K filed with the SEC, in each case for the year ended December 31, 2012. 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 at www.sec.gov.

        We believe that our agreements with RMR, SNH, GOV, SIR and AIC are on commercially reasonable terms. We also believe that our relationships with RMR, SNH, GOV, SIR and AIC and their affiliated and related persons and entities benefit us and, in fact, provide us with competitive advantages in operating and growing our business.

COMPENSATION COMMITTEE INTERLOCKS AND INSIDER PARTICIPATION

        Our Compensation Committee is currently comprised of Messrs. Lamkin, Morea and Zeytoonjian. None of the members of our Compensation Committee is, or has been, an officer or employee of our Company. None of our executive officers serves on the board of directors (or related governing body) or compensation committee of another entity that has an executive officer who serves on our Board or Compensation Committee. Members of our Compensation Committee serve as independent trustees or independent directors and compensation committee members of other public companies managed by or affiliated with RMR.

SECTION 16(A) BENEFICIAL OWNERSHIP REPORTING COMPLIANCE

        Section 16(a) of the Exchange Act requires that our executive officers, Trustees and persons who own more than 10% of a registered class of our equity securities file reports of ownership and changes in ownership of securities with the SEC and the NYSE. Our executive officers, Trustees and greater than 10% shareholders are required to furnish us with copies of all forms they file pursuant to Section 16(a). Based solely on a review of the copies of these reports furnished to us or written representations made to us that no such reports were required, we believe that, during 2012, all filing requirements under Section 16(a) of the Exchange Act applicable to our executive officers, Trustees and persons who own more than 10% of a registered class of our equity securities were timely met.

HOUSEHOLDING OF ANNUAL MEETING MATERIALS

        Some banks, brokers and other record holders of our common shares may participate in the practice of "householding" proxy statements, annual reports and Notices of Internet Availability of those documents. This means that, unless shareholders give contrary instructions, only one copy of our proxy statement, annual report or Notice of Internet Availability may be sent to multiple shareholders in each household. We will promptly deliver a separate copy of any of those documents to you if you write to us at Investor Relations, CommonWealth REIT, Two Newton Place, 255 Washington Street, Suite 300, Newton, Massachusetts 02458, or call us at (617) 796-8222. If you want to receive separate copies of our proxy statement, annual report or Notice of Internet Availability in the future, or if you are receiving multiple copies and would like to receive only one copy per household, you should

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contact your bank, broker or other record holder, or you may contact us at the above address or telephone number.

OTHER MATTERS

        At this time, we know 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 will vote the proxy in accordance with their discretion on such matters to the maximum extent that they are permitted to do so by applicable law.

February 25, 2013

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IMPORTANT

        If your shares are held in your own name, please complete a proxy over the internet or by telephone in the manner provided on the website indicated in the Notice of Internet Availability that you received in the mail; alternatively, please request, complete and return a proxy card today. If your shares are held in "street name," you should provide instructions to your broker, bank, nominee or the other institution holding your shares on how to vote your shares. You may provide instructions to your broker, bank, nominee or other institution over the internet or by telephone if your broker, bank, nominee or other institution offers these options, or you may return a proxy card to your broker, bank, nominee or other institution and contact the person responsible for your account to ensure that a proxy is voted on your behalf.

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

Innisfree M&A Incorporated
501 Madison Avenue, 20th Floor
New York, New York 10022
Brokers and Banks Call Collect at (212) 750-5833
Shareholders Call Toll-Free at (877) 717-3922

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QuickLinks

COMMONWEALTH REIT Two Newton Place 255 Washington Street, Suite 300 Newton, Massachusetts 02458
PROXY STATEMENT FOR THE ANNUAL MEETING OF SHAREHOLDERS
To be held at 9:30 a.m. on Tuesday, May 14, 2013 at Two Newton Place 255 Washington Street, Suite 100 Newton, Massachusetts 02458
INTRODUCTION
PROPOSAL 1 ELECTION OF TRUSTEE
PROPOSAL 2 ADVISORY APPROVAL RELATING TO EXECUTIVE COMPENSATION
PROPOSAL 3 RATIFICATION OF APPOINTMENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM
SOLICITATION OF PROXIES
TRUSTEES AND EXECUTIVE OFFICERS
BOARD OF TRUSTEES
BOARD COMMITTEES
COMMUNICATIONS WITH TRUSTEES
SELECTION OF CANDIDATES FOR TRUSTEES; SHAREHOLDER RECOMMENDATIONS, NOMINATIONS AND OTHER PROPOSALS
COMPENSATION DISCUSSION AND ANALYSIS
COMPENSATION COMMITTEE REPORT
COMPENSATION TABLES
SUMMARY COMPENSATION TABLE FOR 2012, 2011 AND 2010
GRANTS OF PLAN BASED AWARDS FOR 2012 (Shares granted in 2012, including vested and unvested grants)
OUTSTANDING EQUITY AWARDS AT FISCAL YEAR END FOR 2012 (Shares granted in 2012 and prior years, which have not yet vested)
STOCK VESTED FOR 2012 (Share grants that vested in 2012, including shares granted in prior years)
POTENTIAL PAYMENTS UPON TERMINATION OR CHANGE IN CONTROL
TRUSTEE COMPENSATION FOR 2012 (2012 compensation; all share grants to Trustees vest at the time of grant)
AUDIT COMMITTEE REPORT
SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT
RELATED PERSON TRANSACTIONS AND COMPANY REVIEW OF SUCH TRANSACTIONS
COMPENSATION COMMITTEE INTERLOCKS AND INSIDER PARTICIPATION
SECTION 16(A) BENEFICIAL OWNERSHIP REPORTING COMPLIANCE
HOUSEHOLDING OF ANNUAL MEETING MATERIALS
OTHER MATTERS
IMPORTANT