X0202 SCHEDULE 13D/A 0000863064 XXXXXXXX LIVE 4 Common Shares, without par value 03/26/2026 false 0001364125 95805V108 Western Copper and Gold Corporation

Suite 907 - 1030 West Georgia Street Vancouver A1 V6E 2Y3

Andy Hodges, Company Secretary 44 (0) 20 7781 2000 Rio Tinto plc 6 St James's Square London X0 SW1Y 4AD With copy to: Scott Miller 1 212 558-4000 Sullivan & Cromwell LLP 125 Broad Street New York NY 10004 0000863064 N Rio Tinto plc b WC N X0 0 19004925 0 19004925 19004925 N 8.42 HC CO For rows 8, 10, 11 and 13, see Item 5. For row 13, the calculation is based on 225,628,684 common shares, without par value (the "Shares"), being the number of Shares outstanding as of March 25, 2026, as disclosed in the Company's Annual Information Form for the year ended December 31, 2025. Y Rio Tinto Canada Inc. b AF N Z4 0 19004925 0 19004925 19004925 N 8.42 CO For rows 8, 10, 11 and 13, see Item 5. For row 13, the calculation is based on 225,628,684 common shares, without par value (the "Shares"), being the number of Shares outstanding as of March 25, 2026, as disclosed in the Company's Annual Information Form for the year ended December 31,2025. Common Shares, without par value Western Copper and Gold Corporation Suite 907 - 1030 West Georgia Street Vancouver A1 V6E 2Y3 This Amendment No. 4 ("Amendment No. 4") relates to the Statement on Schedule 13D (this "Schedule 13D") filed on April 1, 2026 by Rio Tinto plc, a public limited company incorporated under the laws of England and Wales ("Rio Tinto"), and Rio Tinto Canada Inc., a corporation incorporated under the laws of Canada ("RTCI" and, together with Rio Tinto, the "Rio Tinto Companies"). Except as otherwise provided herein, each item of the Original Schedule 13D remains unchanged. Explanatory Note: This Amendment No. 4 is being filed to reflect a passive decrease of greater than one percent (1%) in the percentage of the Company's Common Shares owned beneficially by the Reporting Persons based on the Company's disclosure of the number of Common Shares outstanding. Item 4 of the Original Schedule 13D is hereby amended and supplemented by adding the following information: The Company discloses the number of its issued and outstanding Common Shares on a quarterly basis. On March 26, 2026, the Company filed its Form 40-F with the Securities and Exchange Commission including as an Exhibit the Company's Annual Information Form for the year ended Dember 31, 2025. The Annual Information Form disclosed on page 26 that "[a]s of March 25, 2026, the Company had 225,628,684 Common Shares issued and outstanding." Item 5 of the Original Schedule 13D is hereby amended and supplemented by adding the following information: The information set forth in Item 4 of this Amendment No. 4 is incorporated by reference in its entirety into this Item 5. There were no other transactions by the reporting persons that were effected during the past 60 days. A Joint Filing Agreement between Rio Tinto plc and Rio Tinto Canada Inc., dated November 23, 2022.* B Subscription Agreement between Western Copper and Gold Corporation and Rio Tinto Canada Inc. dated May 14, 2021.* C Investor Rights Agreement between Western Copper and Gold Corporation and Rio Tinto Canada Inc. dated May 28, 2021.* D Extension letter dated November 22, 2022, from Rio Tinto Canada Inc. to Western Copper and Gold Corporation.* E Subscription Agreement, dated November 27, 2023, between Western Copper and Gold Corporation and Rio Tinto Canada Inc. F Amended and Restated Investor Rights Agreement dated November 27, 2023, between Western Copper and Gold Corporation and Rio Tinto Canada Inc.* G Form of Second Amended and Restated Investor Rights Agreement dated June 13, 2025, between Western Copper and Gold Corporation and Rio Tinto Canada Inc.* * Previously filed. Rio Tinto plc /s/Andy Hodges 04/01/2026 Rio Tinto Canada Inc. /s/Julie Parent 04/01/2026