HIGHLIGHTS

• Appian confirms satisfaction of certain key technical conditions precedent applicable to the remaining undrawn US$350 million under the senior secured project loan facility, following its review of results from the Lowhee infill drilling and ore sorter programs
• Amended credit facility features more favourable terms, including reduced interest rate margins, improved covenants, and an extension of the Company’s option to settle accrued interest in kind for an additional 12 months

Construction readiness activities continue to advance, including detailed engineering, procurement, updated project costs and timing thereof, and project schedule, among other key de-risking initiatives and form part of the remaining conditions precedent to the second draw

Osisko Gold Group Inc. (NYSE: OGG) (TSX-V: OGG) is pleased to announce that it has entered into an amended and restated credit agreement with funds advised by Appian Capital Advisory Limited in respect of its US$450 million senior secured project loan credit facility dated July 21, 2025. The Credit Facility was entered into by the Company’s wholly owned subsidiary, Barkerville Gold Mines Ltd. to finance the development and construction of the Company’s 100%-owned, fully permitted Cariboo Gold Project.

The Amendment provides the Company with more favourable covenants, reduces the overall cost of capital, and extends the Company’s option to settle accrued interest in kind for an additional 12 months. Importantly, following Appian’s review of the results of work completed to date, Appian has confirmed satisfaction of certain key technical conditions precedent to the US$350 million second draw under the Credit Facility, including those related to the Lowhee Zone infill drilling and ore sorting programs, and these conditions have been removed from the Credit Facility pursuant to the Amendment. The second draw remains subject to certain remaining conditions precedent associated with ongoing Project-related construction readiness activities and other customary requirements.

Sean Roosen, Chairman and CEO, commented: “The amended terms of this credit facility provide us with meaningful financial flexibility as we advance the Cariboo Gold Project toward construction readiness. Appian’s confirmation that the key technical conditions precedent have been satisfied, including those related to the completed Lowhee infill drilling and ore sorting programs, represents an important validation of the quality of this deposit and the significant de-risking work our team has completed. With the improved economics under the Amendment and US$350 million of additional capital now substantially de-risked, we are well positioned to continue advancing toward our next major development milestones. We thank Appian for its continued partnership and look forward to working together through the next phase of development at Cariboo.”

The Amendment provides for a reduction in applicable interest rate margins under the Credit Facility as follows: (i) for the initial draw, 3-month Secured Overnight Financing Rate plus a margin of 9.00% per annum (reduced from SOFR plus 9.50% per annum), together with the elimination of the 0.10% per annum SOFR adjustment; and (ii) for the second draw and thereafter, SOFR plus a margin of 7.25% per annum (reduced from SOFR plus 7.50% per annum).

All of the existing guarantees, security and other obligations provided for under the Credit Facility remain in full force and effect and have been reaffirmed in connection with the Amendment. Except as expressly amended, all other terms of the Credit Facility remain unchanged. Barkerville paid an amendment fee to Appian in connection with the Amendment.

The description of the Amendment set forth in this news release is a summary only and is qualified in its entirety by the full text of the amended and restated credit agreement dated August 20, 2026 among Barkerville, as borrower, Appian, as lender, TSX Trust Company, as collateral agent, and Appian ODV (Jersey) Ltd., as administrative agent. A copy of the Amendment will be filed on SEDAR+ (www.sedarplus.ca) under the Company’s issuer profile.

About Appian Capital Advisory Limited

Appian Capital Advisory Limited is the investment advisor to long-term value-focused private capital funds that invest in companies in metals, mining, and adjacent industries. Appian is a leading investment advisor with global experience across South America, North America, Australia and Africa and a successful track record of supporting companies in metals, mining, and adjacent industries to achieve their development targets, with a global operating portfolio overseeing approximately 5,000 employees. Appian has a global team of 88 investment professionals, combining financial and technical expertise, with presences in London, Abu Dhabi, New York, Dubai, Belo Horizonte, São Paulo, Beijing, Hong Kong, Toronto, Lima and Perth.

ABOUT OSISKO GOLD GROUP INC.

Osisko Gold Group Inc. is a continental North American gold development company focused on past producing mining camps with district-scale potential. The Company’s objective is to become an intermediate gold producer through the development of its flagship, fully permitted, 100%-owned Cariboo Gold Project, located within the Company’s broader Cariboo regional land package in central British Columbia, Canada, which hosts numerous prospective exploration targets and provides opportunities for future discoveries. Its Cariboo project pipeline is complemented by the Tintic Project, located in the historic East Tintic mining district in Utah, U.S.A., a brownfield property with significant exploration potential, extensive historical mining data, and access to established infrastructure. Osisko Gold is focused on developing long-life mining assets in mining-friendly jurisdictions while maintaining a disciplined approach to capital allocation, development risk management, and mineral inventory growth.