Mr. Sean Roosen reports

OSISKO DEVELOPMENT ANNOUNCES INCLUSION IN THE GDXJ

Osisko Development Corp. has been included in the VanEck Junior Gold Miners ETF (GDXJ) pursuant to the GDXJ's semi-annual review and rebalancing announced on March 13, 2026, effective at the close of markets on March 20, 2026.

"We are very pleased to be included in the widely followed GDXJ index, which we believe will further elevate our market visibility and trading liquidity profile while broadening access to investors seeking exposure to the gold sector," stated Sean Roosen, chairman and chief executive officer. "This inclusion reflects the significant progress and milestones our team has achieved to date as we continue advancing and derisking our flagship Cariboo gold project."

The GDXJ is a widely recognized exchange-traded fund designed to track the performance of the most liquid small- and mid-capitalization companies in the global gold and silver mining industries.

About Osisko Development Corp.

Osisko Development 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-per-cent-owned Cariboo gold project, located in central British Columbia, Canada. Its project pipeline is complemented by the Tintic project, located in the historic East Tintic mining district in Utah, United States, a brownfield property with significant exploration potential, extensive historical mining data and access to established infrastructure. Osisko Development 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.

We seek Safe Harbor.