The Metals Royalty Co Inc American Stock Offering Circular (May 12, 2026 Edition)

55,061,113 Common Shares This prospectus supplement No.2 updates and amends the prospectus dated April7, 2026, as supplemented by prospectussupplement No.1 dated May7, 2026 (together, the “prospectus”), which relates to registration of the resale of 55,061,113 of ourcommon shares (the “Common Shares”) by our shareholders identified in this prospectus (the “Registered Shareholders”). Unlike aninitial public offering, the resale by the Registered Shareholders is not being underwritten by any investment bank. The registeredshareholders may, or may not, elect to sell their Common Shares covered by the prospectus, as and to the extent they may determine. This prospectus supplement No.2 is being filed to update, amend and supplement the information previously included in theprospectus with the information attached to this prospectus supplement No.2 contained in the Form6-K filed with the Securities andExchange Commission on May11, 2026. You should read this prospectus supplement No.2 together with the prospectus, which is to Our Common Shares are traded on the Nasdaq under the symbol “TMCR.” On May11, 2026, the last reported sale price of ourCommon Shares on the Nasdaq was $13.75 per share. The Securities and Exchange Commission and state securities regulators have not approved or disapproved of thesesecurities, or determined if the prospectus or this prospectus supplement is truthful or complete. Any representation to the The date of this prospectus supplement is May 12, 2026. CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS This prospectus supplement contains forward-looking statements regarding, among other things, our business strategies, financialcondition, operating results, and future plans. These statements are based on the current expectations, estimates, and assumptions ofour management and are not guarantees of future performance. Forward-looking statements are inherently subject to risks, Forward-looking statements generally relate to future events or our future financial or operating performance and may be identified byterminology such as “believe,” “expect,” “intend,” “anticipate,” “estimate,” “plan,” “may,” “will,” “should,” “forecast,” or similar ●the sources and timing of potential revenue from the NORI Royalty as well as the timing and amount of estimated future ●the timing of TMC’s exploration license and commercial recovery permit application review by NOAA under DSHMRA, and anyother assumptions regarding permitting timelines, including both under the ISA and the DSHMRA; ●closing the Transaction, the Private Placement and the Credit Facility (each as later defined herein); ●our potential secured term loan credit facility pursuant to the Credit Agreement Term Sheet (as later defined herein), including theconditions to funding, covenant compliance, interest rate step-ups, mandatory prepayment, make-whole and call protection ●Our ability to negotiate and execute definitive documentation in respect of the Credit Facility (as later defined herein) on theterms set forth in the Credit Facility Term Sheet (as later defined herein), or at all; ●the supply and demand for nickel and cobalt (including critical metals and battery cathode feedstocks), steel-making feedstocks,copper and manganese ores; ●the future prices of nickel and cobalt (including critical metals and battery cathode feedstocks), steel-making feedstocks, copperand manganese ores; ●government regulation of mineral extraction from the deep seafloor and changes in mining laws and regulations; ●assumptions regarding our ability to acquire additional royalty, stream or similar interests in seafloor or other areas under U.S. orU.S. aligned jurisdictions; ●our plans to mitigate our material weakness in our internal control over financial reporting; ●our ability to raise financing in the future, the nature of any such financing and our plans with respect thereto; ●our business and future activities; ●our status as a foreign private issuer; ●our status as an emerging growth company; ●the effect on us of any changes to existing or new legislation or policy or government regulation; ●goals, strategies and future growth; ●expectations around the performance of the NORI Royalty; ●estimates of mineral resources and reserves; ●our ability to retain key management personnel in order to enable us to continue to develop our business; ●statements relating to our status as an emerging growth company and foreign private issuer; ●any reference to or description of the activities proposed to be conducted by TMC or its affiliates; ●projected mining and process recovery rates; ●assumptions as to geotechnical requirements for collector on the seabed; ●assumptions as to environmental, permitting, and social risks; and ●other assumptions described herein or in the accompanying prospectus underlying or relating to any forward-looking statements. We caution you that the foregoing list may not contain all of the forward-looki