X0202 SCHEDULE 13G 0002135683 XXXXXXXX LIVE Class A common stock, par value $0.0001 per share 06/04/2026 0002110105 Quantinuum Inc. 74768A104 303 S Technology Court, Broomfield, CO 80021 Rule 13d-1(d) Cambridge Quantum Holdings Limited b E9 0.00 82884823.00 0.00 82884823.00 82884823.00 N 71.6 HC CQ Invest I LLC b DE 0.00 531720.00 0.00 531720.00 531720.00 N 1.6 OO Ilyas Khan b X0 480511.00 82884823.00 480511.00 82884823.00 83365334.00 N 72.0 IN Waseem Shiraz b X0 27001.00 82884823.00 27001.00 82884823.00 82911824.00 N 71.6 IN Quantinuum Inc. 303 S Technology Court, Broomfield, CO 80021 This statement is being filed on behalf of each of the following persons (collectively, the "Reporting Persons"): Cambridge Quantum Holdings Limited CQ Invest I LLC Ilyas Khan Waseem Shiraz c/o Cambridge Quantum North America Holdings, LLC, 1300 N 17th Street, Suite 530, Arlington, VA 22209 Cambridge Quantum Holdings Limited is organized under the laws of the Cayman Islands. CQ Invest I LLC is organized under the laws of the State of Delaware. Each of Ilyas Khan and Waseem Shiraz is a citizen of the United Kingdom. Y As of the date of this statement, (i) Cambridge Quantum Holdings Limited directly holds 82,353,103 Common Units and a corresponding number of shares of Class B common stock of the Issuer, representing approximately 71.5% of the Issuer's Class A common stock assuming the conversion of Common Units and shares of Class B common stock on a one-to-one basis, and (ii) CQ Invest I LLC directly holds 531,720 common units of Quantinuum Holdings, LLC (the "Common Units") and a corresponding number of shares of Class B common stock of the Issuer, representing approximately 1.6% of the Issuer's Class A common stock assuming the conversion of Common Units and shares of Class B common stock on a one-to-one basis. Each Common Unit (together with a corresponding share of Class B common stock) is exchangeable for one share of Class A common stock of the Issuer (or, at the Issuer's election, cash). Cambridge Quantum Holdings Limited is the administrative manager of CQ Invest I LLC, and has the right to manage, control and conduct the affairs and operations of CQ Invest I LLC. Cambridge Quantum Holdings Limited is managed by a board of directors, which is composed of Ilyas Khan and Waseem Shiraz, who have the power to vote or direct the vote of, and power to dispose or to direct the disposition of, the shares and units held by CQ Invest I LLC. Mr. Khan, including entities controlled by him, is the controlling shareholder of Cambridge Quantum Holdings Limited. Mr. Khan and Mr. Shiraz disclaim beneficial ownership of the securities that may be deemed to be beneficially owned by Cambridge Quantum Holdings Limited and CQ Invest I LLC, except to the extent of their respective pecuniary interest therein. As of the date of this statement, Ilyas Khan directly owns 480,511 shares of Class A common stock in his personal capacity and the other Reporting Persons are not deemed beneficial owners of these securities. As of the date of this statement, Waseem Shiraz directly owns 27,001 shares of Class A common stock in his personal capacity and the other Reporting Persons are not deemed beneficial owners of these securities. The percentage of ownership is based on (i) 32,862,895 shares of Class A common stock and (ii) 82,884,823 shares of Class A common stock beneficially owned by the Reporting Persons, issuable upon conversion as set forth above, as reported by the Issuer in its prospectus dated June 3, 2026. See Item 4(a) hereof. See Item 4(a) hereof. See Item 4(a) hereof. See Item 4(a) hereof. See Item 4(a) hereof. Y Y Y N See Item 2(a) hereof. Y N Not Applicable. Cambridge Quantum Holdings Limited /s/ Waseem Shiraz 06/22/2026 CQ Invest I LLC /s/ Waseem Shiraz 06/22/2026 Ilyas Khan /s/ Ilyas Khan 06/22/2026 Waseem Shiraz /s/ Waseem Shiraz 06/22/2026 Exhibit A, Joint Filing Agreement, dated as of June 22, 2026.