Osisko Development Sells 100% Interest In San Antonio Gold Project To Axo Copper For 15.3M Shares Plus Up To US$4M In Contingent Payments

Osisko Development Corp. (NYSE:ODV, TSXV:ODV) ("Osisko Development" or the "Company") is pleased to announce that it has entered into a securities purchase agreement dated November 21, 2025 (the "Purchase Agreement") with Axo Copper Corp. (TSXV:AXO) ("Axo") to sell its 100% interest in the San Antonio Gold Project ("San Antonio" or the "Project") located in the Sonora State, Mexico. Pursuant to the Purchase Agreement, Axo will acquire Sapuchi Minera S.A. de R.L. de C.V. ("Sapuchi"), which holds a 100% interest in the mineral concessions comprising San Antonio, subject to the satisfaction of certain conditions (the "Transaction").

Upon closing of the Transaction, Osisko Development will receive, subject to adjustment in accordance with the terms of the Purchase Agreement, 15,305,536 common shares of Axo ("Axo Shares") or such other number of Axo Shares that would result in Osisko Development owning 9.99% of the issued and outstanding Axo Shares on a non-diluted basis. Osisko Development will also be entitled to receive the following contingent payments:

• A cash payment equal to 70% of any Mexican value-added tax refund due or owing to Sapuchi in respect of any period of time ending on or before the closing date of the Transaction;
• Upon the public filing by Axo of a feasibility study respecting the Project that is prepared in accordance with NI 43-101, US$2,000,000, payable in cash or Axo Shares, at Axo's option;
• Upon the first gold pour being completed at the Project, US$2,000,000, payable in cash or Axo Shares, at the Company's option; and
• In the event that Axo completes one or more equity financings that result in aggregate gross proceeds of at least US$10,000,000, Axo will issue to Osisko Development such number of Axo Shares that would result in Osisko Development retaining a 9.99% interest in Axo, on a non-diluted basis, on the initial US$10,000,000 raised pursuant to such equity financing.

The Company has agreed that it will hold its Axo Shares for at least 12 months following the closing of the Transaction, and to comply with certain other conditions until the date that is 24 months from the date of completion of the Transaction.

The Project is not considered a material property of the Company and has been in care and maintenance since the third quarter of 2023.

The Transaction is subject to customary closing conditions, including the acceptance of the TSX Venture Exchange.