Cosa launches largest drill program to date at Murphy Lake North with Denison Mines

Vancouver, British Columbia--(Newsfile Corp. - May 28, 2026) - Cosa Resources Corp. ( TSX-V: COSA ) ( OTCQB: COSAF ) ( FSE: SSKU ) (" Cosa " or the " Company ") is pleased to announce summer plans for the largest drill program to date at the Company's Murphy Lake North (" MLN ") project. Drilling is set to commence in mid-June and will follow up on uranium mineralization intersected in winter 2026. Muphy Lake North is a joint venture (the " Joint Venture ") between Cosa and Denison Mines Corp. ( TSX: DML ) ( NYSE American: DNN ) (" Denison ") and is located three kilometres east of IsoEnergy's Hurricane deposit, in the eastern Athabasca Basin, Saskatchewan.

Cosa is the project operator and holds a 70% interest with Denison holding a 30% interest. Highlights Multiple intersections of unconformity related uranium mineralization remain open along strike for 600 metres in both directions; drilling to focus on step-out tests of the Cyclone mineralization approximately 265 metres below surface Largest drill program to date at Murphy Lake North will commence in mid-June and comprise approximately 6,000 metres, 15 drill holes Denison participating in funding 2026 exploration at MLN to maintain its 30% interest Keith Bodnarchuk, President and CEO, commented: " Having intersected 5.0 metres averaging 0.55% U 3 O 8 within an extensive structure and alteration zone that remains open along strike, we are eager to return to site and commence what will be the largest drill program for Cosa and the Murphy Lake North Joint Venture since the inception of the Company. With Denison's support and participation in the funding of ongoing exploration, we are very excited to follow up the uranium mineralization at Murphy Lake North." Andy Carmichael, Vice President of Exploration, commented: " Exploration at Cyclone has progressed from initial drilling on the trend to prepa