Material Agreement (Form 8-K)

On March 31, 2026, we entered into an underwriting agreement, or the Underwriting Agreement, with Yorkville Securities, LLC, as representative of the underwriters named therein, with respect to an underwritten public offering of 416,666,667 of our common shares of beneficial interest, $.01 par value per share, or common shares, at a public offering price of $1.20 per share. We expect to issue and deliver these common shares on or about April 2, 2026, for aggregate gross proceeds of $500,000,000. We also granted the underwriters an option to purchase up to an additional 62,500,000 common shares from us, at the public offering price, less the underwriting discount, within 30 days from the date of the Underwriting Agreement. We expect to use the net proceeds from the offering (after deducting the underwriting discount and estimated offering expenses payable by us), together with cash on hand, to redeem (1) the $100 million principal amount of our outstanding 4.95% Senior Notes due 2027 and (2) $370 million of the $450 million aggregate principal amount of our outstanding 5.50% Senior Notes due 2027 assuming the underwriters do not exercise their option to purchase additional common shares. If the underwriters exercise their option to purchase additional common shares in full, we expect to use the additional net proceeds, together with cash on hand, to redeem additional principal amount of the 5.50% Senior Notes due 2027 to the extent of the additional net proceeds received.

Helix Partners, or Helix, The RMR Group LLC, or RMR, our manager, YA II PN, Ltd., an affiliate of Yorkville Securities, LLC, and another institutional investor have agreed to purchase from the underwriters 55,700,000, 41,666,666, 20,833,333 and 54,166,666, respectively, common shares at a price equal to the public offering price. In addition, Christopher J. Bilotto, one of our Managing Trustees and our President and Chief Executive Officer, and Brian E. Donley, our Chief Financial Officer and Treasurer, as well as certain of our Trustees, have also agreed to purchase from the underwriters an aggregate of 248,333 common shares at the public offering price. Our declaration of trust and bylaws prohibit any shareholder, other than RMR and its affiliates (as defined under Maryland law) and certain persons who have been exempted by our Board of Trustees, or Board, including RMR, from owning, directly and by attribution, more than 9.8% of the number or value of shares (whichever is more restrictive) of any class or series of our outstanding shares of beneficial interest, including our common shares. These restrictions in our declaration of trust and bylaws are intended to, among other purposes, assist with our real estate investment trust, or REIT, compliance under the Internal Revenue Code of 1986, as amended. Further, our bylaws contain provisions that generally prohibit shareholders from owning 5% or more of our outstanding shares, including our common shares. This ownership limitation in our bylaws is intended to help us preserve our ability to use our net operating losses and other tax benefits to reduce our future taxable income. Notwithstanding the foregoing, our Board has agreed to exempt Helix, RMR and an institutional investor from our 5% ownership limitation contained in our bylaws, but subject to each such party other than RMR not exceeding our 9.8% ownership limit.

The Underwriting Agreement contains customary representations, warranties and agreements by us, customary conditions to closing, indemnification obligations of ours and the underwriters named therein, including for liabilities under the Securities Act of 1933, as amended, other obligations of the parties and termination provisions. The Underwriting Agreement also requires each of our officers and directors and RMR to enter into a "lock-up" agreement that generally prohibits, without Yorkville Securities, LLC's prior written consent and subject to certain exceptions, the sale, transfer, or other disposition of common shares for a period of 90 days after March 31, 2026, the date of the Underwriting Agreement. Furthermore, the Company agreed under the Underwriting Agreement not to, directly or indirectly, offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, or otherwise dispose of or transfer any of our common shares or any securities convertible into or exercisable or exchangeable for our common shares for a period of 90 days after March 31, 2026.

These common shares will be issued pursuant to a prospectus supplement dated March 31, 2026, which will be filed with the Securities and Exchange Commission, or the SEC, in connection with a takedown from our shelf registration statement on Form S-3 (File No. No. 333-281645), which became effective on August 19, 2024, the base prospectus dated August 19, 2024 contained in such registration statement and the free writing prospectus, dated and filed with the SEC on March 30, 2026. This Current Report on Form 8-K shall not constitute an offer to sell or the solicitation of an offer to buy nor shall there be any sale of these securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

A copy of the Underwriting Agreement is filed as Exhibit 1.1 to this Current Report on Form 8-K and is incorporated by reference herein. The foregoing summary of such agreement is subject to, and qualified in its entirety by reference to, such exhibit.

Information Regarding Certain Relationships and Related Person Transactions

We have relationships and historical and continuing transactions with RMR, The RMR Group Inc., or RMR Inc., and others related to them. The RMR Group Inc., or RMR Inc., is a holding company and substantially all of its business is conducted by its majority owned subsidiary, RMR. One of our Managing Trustees and Chair of our Board of Trustees, Adam D. Portnoy, is the sole trustee, an officer and the controlling shareholder of ABP Trust, which is the controlling shareholder of RMR Inc., chair of the board of directors, a managing director and the president and chief executive officer of RMR Inc., and an officer and employee of RMR. Christopher J. Bilotto, our other Managing Trustee and our President and Chief Executive Officer, also serves as an executive vice president of RMR Inc. and an officer and employee of RMR. Brian E. Donley, our Chief Financial Officer and Treasurer, is also an officer and employee of RMR. In addition, each of Messrs. Bilotto and Donley also serve as a managing trustee and/or officer of certain other REITs managed by RMR. Some of our Independent Trustees also serve as independent trustees of other public companies to which RMR or its subsidiaries provide management services. Due to the nature of the relationship between us and RMR, the offering and the transactions contemplated by the Underwriting Agreement, including participation of RMR, Messrs. Bilotto and Donley and certain of our Trustees therein, were separately considered and approved by our Independent Trustees and our Board.