SCHEDULE 13G 0002069862 XXXXXXXX LIVE Class A ordinary shares, par value $0.0001 per share 08/04/2025 0002069856 HCM III Acquisition Corp. G4365E103 100 First Stamford Place, Suite 330 Stamford CT 06902 Rule 13d-1(d) HCM Investor Holdings III, LLC E9 8433333.00 0.00 8433333.00 0.00 8433333.00 N 25 OO Shawn Matthews X1 0.00 8433333.00 0.00 8433333.00 8433333.00 N 25 IN (1) See Item 4. Represents Class B ordinary shares, which will automatically convert into the Issuer's Class A ordinary shares at the time of the Issuer's initial business combination, as more fully described under the heading "Description of Securities" in the Issuer's registration statement on Form S-1 (File No. 333-287841). (2) Based on 33,733,333 ordinary shares issued and outstanding as reported in the Issuer's prospectus filed with the Securities and Exchange Commission on July 31, 2025 and assuming the conversion of all the Class B ordinary shares held by HCM Investor Holdings III, LLC. HCM III Acquisition Corp. 100 First Stamford Place, Suite 330 Stamford, CT 06902 HCM Investor Holdings III, LLC and Shawn Matthews (the "Reporting Persons") 100 First Stamford Place, Suite 330 Stamford, CT 06902 HCM Investor Holdings III, LLC is a limited liability company formed under the laws of the Cayman Islands. Shawn Matthews is a citizen of the United States of America. Y The responses to Items 5-11 of the cover pages of this Schedule 13G are incorporated herein by reference. As of August 4, 2025, the Reporting Persons may be deemed to beneficially own 8,433,333 of the Issuer's Class B ordinary shares, representing 25% of the total ordinary shares issued and outstanding and assuming the conversion of all the Class B ordinary shares of the Reporting Persons. The Class B ordinary shares are automatically convertible into the Issuer's Class A ordinary shares at the time of the Issuer's initial business combination on a one-for-one basis, subject to adjustment, as more fully described under the heading "Description of Securities" in the Issuer's registration statement on Form S-1 (File No. 333-287841). The percentage of the Class B ordinary shares held by the Reporting Persons is based on 33,733,333 ordinary shares issued and outstanding as reported in the Issuer's prospectus filed with the Securities and Exchange Commission on July 31, 2025 and assuming the conversion of all the Class B ordinary shares held by HCM Investor Holdings III, LLC. HCM Investor Holdings III, LLC is the record holder of the shares reported herein. Shawn Matthews is the managing member of HCM Investor Holdings III, LLC. Consequently, he may be deemed the beneficial owner of the shares held by HCM Investor Holdings III, LLC and has voting and dispositive control over such securities. Y Y Y Y Y Y HCM Investor Holdings III, LLC /s/ Shawn Matthews 11/14/2025 Shawn Matthews /s/ Shawn Matthews 11/14/2025