Announcement PDF RNS Number : 9196Z Great Southern Copper PLC 21 October 2026 THIS ANNOUNCEMENT CONTAINS INSIDE INFORMATION AS STIPULATED UNDER THE UK VERSION OF THE MARKET ABUSE REGULATION NO 596/2014 WHICH IS PART OF ENGLISH LAW BY VIRTUE OF THE EUROPEAN (WITHDRAWAL) ACT 2018, AS AMENDED. ON PUBLICATION OF THIS ANNOUNCEMENT VIA A REGULATORY INFORMATION SERVICE, THIS INFORMATION IS CONSIDERED TO BE IN THE PUBLIC DOMAIN. 21 October 2026 Great Southern Copper plc (“GSC” or the “Company”) Director/PDMR Shareholdings Great Southern Copper plc (LSE: GSCU), the company focused on copper-gold-silver exploration in Chile, announces that Nicholas Briers, a non-executive Director, sold and repurchased Ordinary Shares through a Bed and ISA arrangement, in order to effect the transfer of the Ordinary Shares to his respective ISA accounts. The transaction is summarised below: Director Shares sold Shares acquired Total holding following notification % of issued Ordinary share capital Nicholas Briers 666,666 666,666 2,977,776 0.33% Engage with the GSC management team directly by asking questions, watching video summaries and seeing what other shareholders have to say. Navigate to our Interactive Investor hub here: https://gscplc.com/ Enquiries: Great Southern Copper plc https://gscplc.com/link/P3xWby Sam Garrett, Chief Executive Officer +44 (0)20 4582 3500 SI Capital Limited Nick Emerson +44 (0)14 8341 3500 BlytheRay Megan Ray / James Mulligan +44 (0) 20 7138 3204 gsc@blytheray.com Notification and public disclosure of transactions by persons discharging managerial responsibilities/ person closely associated with them. 1 Details of the person discharging managerial responsibilities/person closely associated a) Name Nicholas Briers 2 Reason for the notification a) Position/status Non-Executive Director b) Initial notification/ Amendment Initial Notification 3 Details of the issuer, emission allowance market participant, auction platform, auctioneer or auction monitor a) Name Great Southern Copper plc b) LEI 213800RF6N9WA8PZH313 4 Details of the transaction(s): section to be repeated for (i) each type of instrument; (ii) each type of transaction; (iii) each date; and (iv) each place where transactions have been conducted a) Description of the financial instrument, type of instrument Identification code Ordinary shares of 1 pence each GB00BLB5BF24 b) Nature of the transaction A. Sales of shares from share dealing account B. Repurchase of ordinary shares into ISA account c) Price(s) and volume(s) Price(s) £ Volume(s) A 0.015 B 0.015015 666,666 666,666 d) Aggregated information A. Sales B. Repurchase Price(s) £ Volume(s) Total £ A 0.015 B 0.015015 666,666 666,666 10,000.00 10,010.00 e) Date of the transaction 20 October 2026 f) Place of the transaction London Stock Exchange About Great Southern Copper Great Southern Copper PLC is a UK-listed mineral exploration company focused on the discovery of copper-gold-silver deposits in Chile. The Company has the option to acquire mining rights to 100% of Especularita project in the under-explored coastal belt of Chile that is prospective for large scale copper-gold-silver deposits. Chile is a globally significant mining jurisdiction being the world’s largest producer and exporter of copper. The Especularita Project is located in the coastal metallogenic belt of Chile which hosts significant copper mines and deposits, including Teck’s Carmen de Andacollo copper mine, and boasts excellent access to infrastructure such as roads, power and ports. Significant historical small-scale and artisanal workings for both copper and gold are readily evident in the exploration project area. The coastal belt offers deposit type optionality for copper including porphyry and IOCG style deposits as well as newly recognised intrusive-related copper and gold deposits. Great Southern Copper is strategically positioned to support the global market for copper – a critical battery metal in the clean energy transition around the world. The Company is actively engaged in This information is provided by RNS, the news service of the London Stock Exchange. RNS is approved by the Financial Conduct Authority to act as a Primary Information Provider in the United Kingdom. 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