TRMT Tremont Mortgage Trust

SUPPLEMENT TO JOINT PROXY STATEMENT/PROSPECTUS

We and RMRM have agreed to make the following amended and supplemental disclosures to the Joint Proxy Statement/Prospectus. These amended and supplemental disclosures should be read in conjunction with the Joint Proxy Statement/Prospectus, which should be read in its entirety. Page references in the below disclosures are to the Joint Proxy Statement/Prospectus, and defined terms used but not defined herein have the meanings set forth in the Joint Proxy Statement/Prospectus. Without admitting in any way that the disclosures below are material, we and RMRM make the following amended and supplemental disclosures:

TRMT and RMRM did not enter into any confidentiality agreement with each other, nor did either TRMT or RMRM enter into any with any third parties in relation to the proposed Merger or the Merger Agreement.

At this same meeting of the RMRM special committee, representatives of Skadden and UBS and the RMRM special committee also discussed whether the Merger Agreement should use a collar mechanism to ensure that the Merger consideration would remain within a range that was reasonable and beneficial to the interests of RMRM shareholders. Following the discussion, the RMRM special committee determined that a collar mechanism with respect to the Merger consideration was not necessary in light of the companies’ familiarity with each other and the substantial similarity of their respective businesses.

Neither RMRM nor TRMT have any employees. The personnel and various services RMRM and TRMT require to operate their businesses are provided to them by TRA pursuant to their respective management agreements, which provide for the day to day management of the companies’ operations by TRA, subject to the oversight and direction of the RMRM and TRMT boards of trustees, respectively. None of the TRMT special committee, TRMT board of trustees, RMRM special committee, or RMRM board of trustees discussed the possibility of RMRM’s entering into any employment agreements with any executives of TRMT that would entitle such executives to severance packages should their employment be terminated under certain circumstances. Nor, prior to execution of the Merger Agreement, did any of the TRMT special committee, TRMT board of trustees, RMRM special committee, or RMRM board of trustees discuss the appointment of directors to the surviving entity in the Merger.

UBS then compared these multiples and yields for the selected Mortgage REITs with corresponding multiples and dividend yields of RMRM derived from the RMRM Projections. The foregoing analysis indicated the following high, low, mean and median multiples and yields for the selected Mortgage REITs, as compared to corresponding implied multiples and dividend yields of RMRM derived from the RMRM Projections:

UBS then compared these multiples and yields for the selected Mortgage REITs with corresponding multiples and dividend yields of TRMT derived from the TRMT Projections. The foregoing analysis indicated the following high, low, mean and median multiples and yields for the selected Mortgage REITs, as compared to corresponding implied multiples and dividend yields of TRMT derived from the TRMT Projections:

UBS reviewed publicly available information relating to the following nine selected transactions involving REITs:

UBS reviewed, among other things, premium to price as a percentage and implied price to book value ratio (based on the target’s most recently published book value per share prior to the transaction announcement). Financial data of the selected transactions were based on public filings, research analysts’ consensus estimates and other publicly available information. This analysis indicated the following high, low, mean and median for price premiums and implied price to book ratios:

RMRM. UBS performed a dividend discount analysis of RMRM to calculate a range for the implied share price of RMRM. UBS estimated the present value of the distributable cash flows that RMRM was forecasted to generate during the second quarter of RMRM’s fiscal year ending December 31, 2021, through the full fiscal year ending December 31, 2025, based on the RMRM Projections. UBS calculated terminal values for RMRM by applying a range of multiples to RMRM’s Terminal Book Value Per Share of 0.8x to 1.0x as selected by UBS in its professional judgement, and as provided for in the RMRM Projections. The present values (as of March 31, 2021) of the distributable cash flows and terminal values were then calculated using a range of discount rates from 15.0% to 19.0% as selected by UBS in its professional judgement.

TRMT. UBS performed a dividend discount analysis of TRMT to calculate a range for the implied share price of TRMT. UBS estimated the present value of the distributable cash flows that TRMT was forecasted to generate during the second quarter of TRMT’s fiscal year ending December 31, 2021, through the full fiscal year ending December 31, 2025, based on the TRMT Projections. UBS calculated terminal values for TRMT by applying a range of multiples to TRMT’s Terminal Book Value Per Share of 0.8x to 1.0x as selected by UBS in its professional judgement, and as provided for in the TRMT Projections. The present values (as of March 31, 2021) of the distributable cash flows and terminal values were then calculated using a selected range of discount rates from 15.0% to 19.0% as selected by UBS in its professional judgement.

TRMT. Citi performed a dividend discount analysis of TRMT to calculate the estimated present value of the dividends that TRMT was forecasted to pay during the calendar years ending December 31, 2021 through December 31, 2025 based on the TRMT forecasts. Citi calculated implied terminal values for TRMT by applying to TRMT’s calendar year 2025 estimated book value of equity a range of BVPS multiples of 0.90x to 1.10x, selected based on Citi’s professional judgment and taking into account observed implied BVPS multiples of selected companies in the mortgage REIT sector over time. The present values (as of December 31, 2020) of such dividends and terminal values were then calculated using a selected range of discount rates of 22.2% to 30% derived from a weighted average cost of capital calculation. This analysis indicated an approximate implied per share equity value reference range for TRMT of $4.73 to $6.70.

RMRM. Citi performed a dividend discount analysis of RMRM to calculate the estimated present value of the dividends that RMRM was forecasted to pay during the calendar years ending December 31, 2021 through December 31, 2025 based on the RMRM forecasts. Citi calculated implied terminal values for RMRM by applying to RMRM’s calendar year 2025 estimated book value of equity the same selected range of BVPS multiples described above under the heading “— Dividend Discount Analyses — TRMT.” The present values (as of December 31, 2020) of such dividends and terminal values were then calculated using a selected range of discount rates of 17.7% to 25.4% derived from a weighted average cost of capital calculation. This analysis indicated an approximate implied per share equity value reference range for RMRM of $8.73 to $12.93.

As the TRMT special committee was aware, Citi and its affiliates in the past have provided, currently are providing and in the future may provide investment banking, commercial banking and other similar financial services to TRMT and/or certain of its affiliates and RMR Inc. and/or certain of its affiliates or entities (other than TRMT and RMRM) managed by or that receive business management services from RMR Inc., including through TRA, and/or certain of its affiliates unrelated to the proposed Merger, for which services Citi and its affiliates have received and expect to receive compensation, including, during the approximately two-year period prior to the date of Citi’s opinion, having acted or acting as (i) in the case of TRMT, (A) buyer and lender under a master repurchase agreement regarding certain mortgage loans and other assets of TRMT and (B) joint bookrunning manager for an equity offering of TRMT and (ii) in the case of RMR Inc., (A) financial advisor to certain entities managed by or that receive business management services from RMR Inc. in connection with certain restructuring transactions, (B) joint bookrunning manager for certain equity and debt offerings of RMR Inc. and/or certain entities managed by or that receive business management services from RMR Inc. and (C) joint lead arranger, joint bookrunning manager, syndication agent, collateral agent, administrative agent and/or documentation agent for, and/or as a lender under, certain credit or securitization facilities of certain entities managed by or that receive business management services from RMR Inc., for which services described in clauses (i) and (ii) above Citi and its affiliates received during such approximately two-year period aggregate fees of approximately $0.3 million from TRMT and approximately $37.0 million from RMR Inc. Although Citi and its affiliates have not provided investment banking, commercial banking or other similar financial services to RMRM during the approximately two-year period prior to the date of Citi’s opinion for which Citi and its affiliates received compensation, Citi and its affiliates in the future may provide such services to RMRM and/or its affiliates for which services Citi and its affiliates would expect to receive compensation. In the ordinary course of business, Citi and its affiliates may actively trade or hold the securities or financial instruments (including loans and other obligations) of TRMT, RMRM, RMR Inc. and/or their respective affiliates or entities managed by or that receive business management services from RMR Inc. or its affiliates for their own account or for the account of Citi’s customers and, accordingly, may at any time hold a long or short position or otherwise effect transactions in such securities or financial instruments. In addition, Citi and its affiliates (including Citigroup Inc. and its affiliates) may maintain relationships with TRMT, RMRM, RMR Inc., entities managed by or that receive business management services from RMR Inc. and/or their respective affiliates.

Neither TRMT nor RMRM has any employees. Neither TRMT, on the one hand, nor RMRM, on the other hand, entered into any employment agreements or held discussions with officers of TRMT regarding employment with the surviving entity in the Merger.

Additional Information about the Merger

In connection with the Merger, RMRM has filed with the Securities and Exchange Commission, or the SEC, a Registration Statement on Form S-4 of which the Joint Proxy Statement/Prospectus and other documents with respect to the Merger, which was declared effective by the SEC on July 26, 2021. This communication does not constitute an offer to sell or the solicitation of an offer to buy any securities or a solicitation of any vote or approval. SHAREHOLDERS ARE URGED TO READ THE JOINT PROXY STATEMENT/PROSPECTUS (INCLUDING ALL AMENDMENTS AND SUPPLEMENTS THERETO) AND ANY OTHER DOCUMENTS FILED OR TO BE FILED WITH THE SEC IN CONNECTION WITH THE MERGER OR INCORPORATED BY REFERENCE IN THE JOINT PROXY STATEMENT/PROSPECTUS BECAUSE THEY CONTAIN AND WILL CONTAIN IMPORTANT INFORMATION ABOUT THE MERGER.

The Joint Proxy Statement/Prospectus has been mailed to TRMT’s and RMRM’s shareholders. Shareholders may obtain free copies of the Registration Statement on Form S-4, the Joint Proxy Statement/Prospectus and any other relevant documents filed or to be filed with the SEC at the SEC’s website at www.sec.gov. In addition, shareholders may obtain free copies of TRMT’s filings with the SEC from TRMT’s website at www.trmtreit.com or RMRM’s filings with the SEC from RMRM’s website at www. rmrmortgagetrust.com.

Participants in the Solicitation Relating to the Merger

TRMT, RMRM and their respective trustees and executive officers, and Tremont Realty Advisors LLC, The RMR Group LLC, The RMR Group Inc. and certain of their respective directors, officers and employees, may be deemed to be participants in the solicitation of proxies from TRMT and RMRM shareholders in respect of the Merger and the other transactions contemplated by the Merger Agreement. Information regarding the persons who may, under the rules of the SEC, be considered participants in the solicitation of TRMT’s and RMRM’s shareholders in connection with the Merger and the other transactions contemplated by the Merger Agreement is set forth in the Joint Proxy Statement/Prospectus. Information regarding TRMT’s trustees and executive officers and RMRM’s trustees and executive officers can be found in TRMT’s and RMRM’s respective definitive proxy statement for its 2021 Annual Meeting of Shareholders. These documents are available free of charge on the SEC’s website and from TRMT or RMRM, as applicable, using the sources indicated above.

Warning Concerning Forward-Looking Statements

This supplement to the Joint Proxy Statement/Prospectus contains statements that constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 and other securities laws. Also, whenever we use words such as “believe”, “expect”, “anticipate”, “intend”, “plan”, “estimate”, “will”, “may” and negatives or derivatives of these or similar expressions, we are making forward-looking statements. These forward-looking statements are based upon our present intent, beliefs or expectations, but forward-looking statements are not guaranteed to occur and may not occur. Actual results may differ materially from those contained in or implied by our forward-looking statements as a result of various factors. Forward-looking statements involve known and unknown risks, uncertainties and other factors, some of which are beyond our control. For example:

The information contained in our filings with the SEC, including under “Risk Factors” in our periodic reports or incorporated therein, identifies other important factors that could cause our actual results to differ materially from those stated in or implied by our forward-looking statements. Our filings with the SEC are available on the SEC’s website at www.sec.gov.

You should not place undue reliance upon forward-looking statements.

Except as required by law, we do not intend to update or change any forward-looking statements as a result of new information, future events or otherwise.