Osisko Gold Group Inc. (NYSE: OGG) (TSX-V: OGG) is pleased to announce that it has completed its previously announced offering of US$600 million aggregate principal amount of 9.250% senior secured notes due 2031. The Notes will mature on October 1, 2031, and are non-callable for the first two years, and will pay interest semi-annually in arrears on April 1 and October 1 of each year, commencing on April 1, 2027.

The Notes offering was completed on a private placement basis to persons reasonably believed to be qualified institutional buyers in accordance with Rule 144A under the United States Securities Act of 1933, as amended and outside of the United States pursuant to Regulation S under the Securities Act.

Sean Roosen, Chairman and CEO, commented: “With construction of the Cariboo Gold Project underway following our positive final investment decision earlier this month, the completion of this offering further bolsters our already strong balance sheet position and, together with other available sources of capital, fully funds us through commercial production anticipated in 2029. Refinancing the existing Appian project finance facility on cost-effective terms lowers our overall cost of capital and provides greater financial flexibility as we progress construction. The exceptional support from leading institutional investors underscores the quality of the Cariboo Gold Project, our development strategy and management’s ability to deliver. Our focus remains on disciplined project execution while concurrently advancing exploration programs aimed at unlocking the vast exploration potential of the Project and its broader regional land package.”

The Notes are fully and unconditionally guaranteed by certain of the Company’s subsidiaries, which, at closing, consisted of Barkerville Gold Mines Ltd., its subsidiary that holds the Cariboo Gold Project in British Columbia, Canada, and are secured by a first priority lien on the Company’s and each guarantor’s property, including equity interests owned by the Company and each guarantor in their respective subsidiaries, the interest reserve account and disbursement account described below, and personal and real property, subject to certain exceptions.

The net proceeds from the Offering were approximately US$578.0 million, after deducting the initial purchasers’ discounts and commissions and estimated offering expenses. The net proceeds from the Offering were used to:

• repay all amounts outstanding, and terminate all commitments, under the Company’s senior secured credit facility with Appian Capital Advisory Limited with approximately US$120.8 million of the net proceeds from the Offering;
• fund a segregated interest reserve account in an amount equal to the first five interest payments on the Notes; and
• fund, with the remaining net proceeds, a segregated disbursement account with funds to be used to advance the Cariboo Gold Project.

Table 1 below summarizes the estimated sources and uses of capital from August 1, 2026, through to forecasted commercial production in H2 2029, after giving effect to the net proceeds from the Offering.

TABLE 1: Estimated Sources and Uses of Capital (from August 1, 2026 to commercial production)¹

1. Totals may not add up due to rounding. Assuming a USD:CAD exchange rate of C$1.38 per US$1.00.
2. As adjusted cash and cash equivalents give effect to US$30 million (C$41 million) in expected gross proceeds from the Trafigura equity investment announced September 14, 2026.
3. Net proceeds from the Offering of approximately US$578.0 million less repayment of approximately US$120.8 million of amounts outstanding under the Appian Credit Facility.
4. Exploration expenditures include remaining flow-through expenditure obligations of approximately C$22 million, with the balance related to planned exploration activities across conversion, infill, and CGP deeps exploration surface and underground drilling.

In connection with the Offering, the initial purchasers purchased the Notes at a purchase price of 98.25% of the principal amount of the Notes.

The offer and sale of the Notes have not been and will not be registered under the Securities Act, or any state securities laws, or qualified by way of a prospectus in any province or territory of Canada. The Notes may not be offered or sold in the United States or to U.S. persons absent registration or an applicable exemption from the registration requirements of the Securities Act and applicable state securities laws. The Notes sold to persons located or resident in Canada are subject to a customary four-month hold period under Canadian securities laws.

This news release is neither an offer to sell nor a solicitation of an offer to buy any of the Notes being offered in the Offering, nor shall it constitute an offer, solicitation or sale of any Notes in any state or jurisdiction in which such an offer, solicitation or sale would be unlawful prior to the registration or qualification thereof under the securities laws of any such state or jurisdiction.

For further information, visit our website at www.osiskogold.ca or contact:

Sean Roosen                                                                Philip Rabenok
Chairman and CEO                                                       Vice President, Investor Relations
Email: sroosen@osiskogold.ca                                  Email: prabenok@osiskogold.ca
Tel: +1 (514) 940-0685                                                  Tel: +1 (437) 423-3644