Arizona Sonoran Provides Update on Nuton Option to Joint Venture

On December 29, 2025, Arizona Sonoran (ASCU) announced the commencement of discussions with Nuton LLC (a Rio Tinto venture) for an "amicable early termination" of Nuton’s option to joint venture on the Cactus Project. Consequently, ASCU intends to advance the project on a 100% standalone basis. The company has set a definitive timeline to complete a standalone Definitive Feasibility Study (DFS) in the second half of 2026, with a Final Investment Decision (FID) targeted for Q4 2026. This follows a period of heavy de-risking, including a Pre-Feasibility Study (PFS) filed in November 2025 and significant equity raises.

• Strategic Shift to 100% Ownership: The termination of the Nuton option removes the potential for a Rio Tinto-backed joint venture. While this ensures ASCU retains 100% of the project's $2.3 billion post-tax NPV8%, it significantly increases the company's financial burden. ASCU no longer has a "major" partner to share the $977 million initial capital expenditure.
• Management Confidence: The move suggests management believes the project's economics are robust enough to attract traditional project debt and that Nuton's specific leaching technology may not be as critical to the base-case standalone plan as previously envisioned.
• Financial Readiness: ASCU enters 2026 with approximately US$100 million in cash. However, this is only ~10% of the required initial capex, meaning massive dilution or complex debt structures are inevitable before the 2029 production target.
• Execution Risk: By going standalone, ASCU assumes all operational and construction risks for a brownfield project of significant scale in a Tier 1 jurisdiction.

Arizona Sonoran is developing the Cactus Project, a brownfield copper site in Pinal County, Arizona. The project includes the Cactus West, Cactus East, and Parks/Salyer deposits. - Flagship Metrics (2025 PFS): Post-tax NPV8% of US$2.3 billion and an IRR of 22.8%. - Mine Life: 22 years (based on PFS). - Production: Projected average of 226 million lbs of copper annually for the first 10 years. - Processing: Conventional open-pit mining with heap leach SXEW (solvent extraction/electrowinning) to produce copper cathode. - Jurisdiction: Private land in Arizona, significantly reducing the federal permitting burden compared to projects on BLM or Forest Service land.