An anonymous director reports

MARIMACA COPPER ANNOUNCES CLOSING OF CANADIAN OFFERING FOR C$257 MILLION (~A$266 MILLION) OF C$409 MILLION (~A$423 MILLION) GLOBAL OFFERING

Marimaca Copper Corp. has closed its previously announced Canadian treasury and secondary offering, with closing of its Australian secondary offering expected in the coming days.

Global offering details

The global offering comprises two parts:

• Canadian offering:
  • Canadian treasury offering: $136.5-million (Canadian) treasury offering of 13.65 million common shares of the company priced at $10 (Canadian) per common share;
  • Canadian secondary offering: $120.5-million (Canadian) secondary offering of 12,049,087 existing common shares at the Canadian issue price owned and controlled by Greenstone Resources II LP and Greenstone Co-Investment No. 1 (Coro) LP;
• Australian offering:
  • Australian secondary offering: $157-million (Australian) secondary offering of 15,200,913 existing CHESS depositary interests (CDIs) of the company at a price of $10.35 (Australian) per CDI owned and controlled by Greenstone Resources II LP and other shareholders.

The Canadian treasury offering represents aggregate gross proceeds to the company of approximately $136.5-million (Canadian) or $141-million (Australian) (1). The Canadian secondary offering and Australian secondary offering combined represent aggregate gross proceeds to the selling shareholders of approximately $272.5-million (Canadian) or $282-million (Australian) (1).

Canadian offering

The Canadian offering was conducted on a commercially reasonable efforts basis with the Canadian co-lead agents (defined below) and consisted of a Canadian treasury offering of common shares for $136.5-million (Canadian) and a Canadian secondary offering of existing common shares, owned and controlled by the Greenstone group, for $120.5-million (Canadian). Collectively, the Canadian offering consisted of 25,699,087 common shares at the Canadian issue price for aggregate gross proceeds of $257-million (Canadian).

The Canadian offering was made pursuant to a prospectus supplement dated Feb. 19, 2026, to the company's short form base shelf prospectus dated Jan. 9, 2026, to purchasers in all of the provinces and territories of Canada (other than Quebec and Nunavut) and in the United States to qualified institutional buyers (QIBs) under the United States Securities Act of 1933, as amended, and in those jurisdictions outside Canada and the United States pursuant to exemptions from prospectus and registration requirements. The Canadian treasury offering remains subject to final approval of the Toronto Stock Exchange.

Australian offering

The Australian offering is being completed as a brokered placement of CDIs by the joint lead managers (defined below) and consists of an Australian secondary offering of existing CDIs, owned and controlled by certain selling shareholders, for expected proceeds of $157-million (Australian). Allotment of the CDIs is expected to occur in the coming days.

Use of funds

The net proceeds from the Canadian treasury offering will be used to advance the Marimaca project, including financing the preconstruction decision engineering work streams and early site works, to conduct a drilling campaign at Pampa Medina, and for working capital and general corporate purposes.

The net proceeds of the Canadian secondary offering were paid to the Greenstone group. The net proceeds of the Australian secondary offering are payable to the selling shareholders. The company did not and will not receive any proceeds from the secondary offering.

Agents

Beacon Securities Ltd. and BMO Capital Markets, together with Euroz Hartleys Ltd. and Canaccord Genuity (Australia) Ltd., acted as co-lead agents and joint bookrunners to the global offering.

The Canadian co-lead agents acted on behalf of a syndicate of agents, including National Bank Financial Inc., ATB Capital Markets Inc., Paradigm Capital Inc. and Raymond James Ltd., for the canadian offering.

Related party transaction disclosure

Existing insiders of the company, Assore International Holdings Ltd. (AIH) and Ithaki Ltd., participated in the Canadian treasury offering for 4.17 million common shares and 3,412,500 common shares, respectively. Such participation by each of AIH and Ithaki constitutes a related party transaction within the meaning of Multilateral Instrument 61-101, Protection of Minority Security Holders in Special Transactions, for which the company was exempt from the formal valuation and minority shareholder approval requirements pursuant to sections 5.5(a) and 5.7(1)(a) of MI 61-101, respectively. The company did not file a material change report 21 days before closing of the Canadian treasury offering as the full terms of the global offering, including details of the insider participation were not settled until shortly prior to closing and the company wished to complete the global offering as expeditiously as possible for sound business reasons. The material change report to be filed by the company in connection with the closing of the global offering will contain additional details with respect to such insider participation in accordance with Canadian securities laws.

Other information

Pursuant to an existing agreement between the company and Mitsubishi Corp., the company has provided Mitsubishi with a notice to purchase additional common shares in order to maintain its pro rata shareholdings as a result of the Canadian treasury offering. Based on public filings and information available to the company, Mitsubishi currently holds approximately 4,640,371 common shares, which represented approximately 3.86 per cent of the then outstanding common shares prior to completion of the Canadian treasury offering and approximately 3.47 per cent following completion of the Canadian treasury offering. The participation right is exercisable by Mitsubishi for a period of 30 business days following the closing of the Canadian treasury offering and if exercised will be completed by way of private placement and subject to approval by the TSX.

About Marimaca Copper Corp.

Marimaca is a copper exploration and development company focused on its 100-per-cent-owned flagship Marimaca copper project and surrounding exploration properties located in Antofagasta region, Chile.

The Marimaca copper project hosts the Marimaca oxide deposit (MOD), an IOCG-type (iron oxide, copper and gold) copper deposit. The company is currently progressing the Marimaca copper project through detailed engineering and submission for sectorial permits following the release of the 2025 MOD DFS and receipt of the RCA. In parallel, the company is exploring its extensive land package in the Antofagasta region, including the more-than-15,000-hectare wholly owned Sierra de Medina property block, located 25 kilometres from the MOD. The company is currently completing a phase II drilling program (30,000 metres) at Pampa Medina, located in the Sierra de Medina property, after a successful discovery drilling program in 2025 identified a high-grade sedimentary horizon at depth.

(1) Based on an Australian-dollar/Canadian-dollar exchange rate of 0.9661.

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