McEwen Copper Inc., a subsidiary of McEwen Mining Inc. (NYSE: MUX) (TSX: MUX), is pleased to announce a binding agreement for an additional $10.0 million investment by Nuton LLC, a Rio Tinto Venture, and existing McEwen Copper shareholder.

Nuton has agreed to invest US$10.0 million to acquire shares of McEwen Copper in a two-part transaction expected to close by October 19^th, 2023 consisting of a private placement of 152,615 McEwen Copper common shares, and the purchase of 232,000 common shares owned by McEwen Mining in a secondary sale. Proceeds of the subscription and purchase are expected to be approximately $4.0 million to McEwen Copper and $6.0 million to McEwen Mining, respectively. The proceeds of the private placement will be used to advance the development of the Los Azules copper project in San Juan, Argentina, and for general corporate purposes.

After closing, Nuton will own 14.5% of McEwen Copper on a fully diluted basis, and McEwen Mining will own 47.7%. The transaction values McEwen Copper at approximately US$800 million.

In connection with the Transaction, McEwen Copper and certain of its affiliates agreed to amend the Nuton Collaboration Agreement to extend the period of exclusivity over novel, trade secret or patented copper heap leach technologies until February 1^st, 2025.

This press release shall not constitute an offer to sell or the solicitation of an offer to buy, nor shall there be any sale of these securities in any jurisdiction in which such offer, solicitation or sale would be unlawful.

About Nuton

Nuton is an innovative new venture that aims to help grow Rio Tinto’s copper business. At the core of Nuton is a portfolio of proprietary copper leach-related technologies and capability – a product of almost 30 years of research and development. Nuton^™ Technologies offer the potential to economically unlock copper sulphide resources, copper bearing waste and tailings, and achieve higher copper recoveries on oxide and transitional material, allowing for a significantly increased copper production. One of the key differentiators of Nuton is the potential to deliver leading environmental performance, including more efficient water usage, lower carbon emissions, and the ability to reclaim mine sites by reprocessing mine waste.

About McEwen Copper

McEwen Copper Inc. holds a 100% interest in the Los Azules copper project in San Juan, Argentina and the Elder Creek project in Nevada, USA.

Los Azules was ranked in the top 10 largest undeveloped copper deposits in the world by Mining Intelligence (2022). Its current copper resources are estimated at 10.9 billion pounds at a grade of 0.40% Cu (Indicated category) and an additional 26.7 billion pounds at a grade of 0.31% Cu (Inferred category). A PEA published in June 2023 estimated a $2.7 billion after-tax NPV8% at $3.75/lb Cu and a 27-year mine life.

After closing the Stellantis investment, also announced today, and the pending investment by Nuton, McEwen Copper will have 30,937,615 common shares outstanding, and its shareholders are: McEwen Mining Inc. 47.7%, Stellantis 19.4%, Nuton 14.5%, Rob McEwen 12.9%, Victor Smorgon Group 3.2%, and other shareholders 2.3%.