Cosa Announces Summer Drill Plans for the Darby Joint Venture with Denison Mines

Vancouver, British Columbia, June 15 2026 – Cosa Resources Corp. (TSX-V: COSA) (OTCQB: COSAF) (FSE: SSKU) (“Cosa” or the “Company”) is pleased to announce summer plans for the Company’s Darby (“Darby”) project. Darby is a joint venture (the “Joint Venture”) between Cosa and Denison Mines Corp. (“Denison”) (TSX: DML) (NYSE American: DNN) and is located 10 kilometres west of Cameco’s Cigar Lake Mine in the eastern Athabasca Basin, Saskatchewan (Figure 1). Cosa is the operator of Darby and holds a 70% interest with Denison holding a 30% interest. Drilling at Darby is expected after completion of a significant drill program at the Company’s Murphy Lake North joint venture to follow up uranium mineralization intersected in winter 2026.