Gunnison Copper Launches Major District-Wide Drilling Program to Support Resource Expansion, Metallurgical Optimization, and Resource Conversion

Drilling Program Includes up to 120 Drill Holes Totalling ~138,000 feet (42,000 meters)

Phoenix, June 4, 2026 - Gunnison Copper Corp. (TSX: GCU) (OTCQB: GCUMF) (FSE: 3XS0) ("Gunnison" or the "Company") is pleased to announce a major district-wide drilling program at its Gunnison Copper Project, including the Strong & Harris satellite deposit, located in Arizona's Cochise Mining District.

The entire drilling program has now been fully contracted and committed with drill rig mobilization expected to commence this month. The program consists of up to 120 drill holes totaling approximately 138,000 feet (42,000 meters) of drilling and is designed to support ongoing Pre-Feasibility Study ("PFS") work program activities, resource expansion, metallurgical optimization, and resource conversion across the Company's district-scale copper assets.

"We are moving forward with a great sense of urgency to deliver on our vision of fueling America's security and prosperity by acting to rapidly increase the domestic copper supply," said Craig Hallworth, President and CEO of Gunnison Copper. "This program is designed not only to potentially add more copper to our flagship project, but also support metallurgical optimization and the resource conversion required to support a mineral reserve in our planned PFS."

Work will begin with metallurgical optimization drilling utilizing two drill rigs until the construction of a new larger core processing and storage facility is completed, expected during the third quarter of 2026, after which the Company plans to increase drilling capacity to as many as six drill rigs. The total direct cost of the drill program and associated laboratory testing is estimated at US$15.0M, excluding employee payroll, with preliminary results expected within six months and full results within 12 to 15 months.

Metallurgical Optimization

The metallurgical program is expected to include up to 36 drill holes totaling approximately 33,000 feet (10,000 meters) of representative samples across the Gunnison and Strong & Harris deposits.

The objective is to provide additional samples for ongoing metallurgical test work, engineering studies, and mine planning activities supporting the Company's PFS work program and permitting initiatives. This includes a material increase in column leach tests, which are the industry standard for predicting and optimizing full-scale copper heap leaching. Up to 270 column leach tests are planned over the next 12 months.

Resource Expansion and Conversion

Following completion of the initial metallurgical drilling phase, the Company will focus on a comprehensive resource drilling program expected to include up to 84 drill holes totaling approximately 105,000 feet (32,000 meters).

The objectives of the resource drilling program include:

• Resource expansion through testing extensions of known mineralization and identifying new mineralized zones;
• Upgrading Inferred Mineral Resources to Measured and Indicated categories;
• Further defining the limits of mineralization at both the Gunnison and Strong & Harris deposits; and
• Evaluating the continuation of the Gunnison mineralized system at depth.

District-Scale Opportunity

The Gunnison Copper Project and the Strong & Harris satellite deposit form part of Gunnison's district-scale land package in Arizona's Southern Copper Belt. The Company believes significant opportunities remain to expand and further define mineralization across multiple deposits located within economic trucking distance of the planned processing infrastructure.

ABOUT GUNNISON COPPER

Gunnison Copper Corp. is a multi-asset pure-play copper developer and producer that controls the Cochise Mining District (the district), containing 12 known deposits within an 8 km economic radius, in the Southern Arizona Copper Belt.

Its flagship asset, the Gunnison Copper Project, has a main pit Measured and Indicated Mineral Resource containing over 846 million tons with a total copper grade of 0.33% (Measured Mineral Resource of 192 million tons at 0.37% and Indicated Mineral Resource of 655 million tons at 0.31%).

The Strong & Harris satellite deposit, located approximately 1.9 miles from the Gunnison processing facilities, is also included in the mine plan and hosts an Inferred Mineral Resource of 76 million tons grading 0.49% total copper (0.32% CuOx) at a 0.07% cutoff, 0.56% zinc and 0.12% silver, containing approximately 740 million pounds of copper, including 483 million pounds of oxide copper, as well as zinc (856 million pounds) and silver (9.0 million ounces).

A preliminary economic assessment ("PEA") was completed in March 2026 for the Gunnison Project yielding robust economics including an NPV8% of $2 billion, IRR of 23%, and payback period of 3.9 years. It is being developed as a conventional operation with open pit mining, heap leach, and SX/EW refinery to produce finished copper cathode on-site with direct rail link. The PEA is preliminary in nature and includes Inferred Mineral Resources that are considered too speculative geologically to have the economic considerations applied to them that would enable them to be categorized as mineral reserves. There is no certainty that the conclusions reached in the PEA will be realized. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.

In addition, Gunnison's Johnson Camp Asset, which is now in production, is fully funded by Nuton LLC, a Rio Tinto Venture, with a production capacity of up to 25 million lbs of finished copper cathode annually.

Other significant deposits controlled by Gunnison in the district, with potential to be economic satellite feeder deposits for Gunnison Project infrastructure, include South Star, and eight other deposits.

For more information on the Company, please visit our website at www.GunnisonCopper.com.

For additional information on the Gunnison Project please refer to the technical report titled "Gunnison Project NI 43-101 Technical Report, Preliminary Economic Assessment, Cochise County, Arizona, USA" with an effective date of March 18, 2026 filed on SEDAR+ at www.sedarplus.ca.

For additional information on the Johnson Camp Mine please refer to the technical report titled "Johnson Camp Mine NI 43-101 Technical Report, Cochise County, Arizona, USA" with an effective date of March 18, 2026 filed on SEDAR+ at www.sedarplus.ca.

Dr. Roland Goodgame, Senior VP of Project Development of the Company is a Qualified Person as defined by NI 43-101. Dr. Goodgame has reviewed and is responsible for the technical information contained in this news release.

Cautionary Note Regarding Forward-Looking Information

This news release contains "forward-looking information" concerning anticipated developments and events that may occur in the future. Forward-looking information contained in this news release includes, but is not limited to, statements with respect to: (i) the intention to deploy the Nuton® technology at the Johnson Camp mine and future production therefrom; (ii) the continued funding of the stage 2 work program by Nuton; (iii) the details and expected results of the stage two work program; (iv) future production and production capacity from the Company's mineral projects; (v) the results of the preliminary economic assessment on the Gunnison Project; (vi) the exploration and development of the Company's mineral projects; (vii) the details and timelines associated with the Company's PFS work program; (viii) the expected results of the Company's PFS work program; (ix) the vision of fueling America's security and prosperity by acting to rapidly increase the domestic copper supply; and (x) the significant opportunities to expand and further define mineralization across multiple deposits.

In certain cases, forward-looking information can be identified by the use of words such as "plans", "expects" or "does not expect", "budget", "scheduled", "estimates", "forecasts", "intends", "anticipates" or "does not anticipate", or "believes", or variations of such words and phrases or state that certain actions, events or results "may", "could", "would", "might", "occur" or "be achieved" suggesting future outcomes, or other expectations, beliefs, plans, objectives, assumptions, intentions or statements about future events or performance. Forward-looking information contained in this news release is based on certain factors and assumptions regarding, among other things, Nuton will continue to fund the stage 2 work program, the availability of financing to continue as a going concern and implement the Company's operational plans, the allocation of the 48C tax credits between the Company and Nuton, the satisfaction of the requirements set forth in Section 48C of the Internal Revenue Code, the estimation of mineral resources, the realization of resource estimates, copper and other metal prices, the timing and amount of future development expenditures, the estimation of initial and sustaining capital requirements, the estimation of labour and operating costs (including the price of acid), the availability of labour, material and acid supply, receipt of and compliance with necessary regulatory approvals and permits, the estimation of insurance coverage, and assumptions with respect to currency fluctuations, environmental risks, title disputes or claims, and other similar matters. While the Company considers these assumptions to be reasonable based on information currently available to it, they may prove to be incorrect.

Forward-looking information involves known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievements of the Company to be materially different from any future results, performance or achievements expressed or implied by the forward-looking information. Such factors include risks related to the Company not obtaining adequate financing to continue operations, Nuton failing to continue to fund the stage 2 work program, the failure to satisfy the requirements set forth in Section 48C of the Internal Revenue Code, the breach of debt covenants, risks inherent in the construction and operation of mineral deposits, including risks relating to changes in project parameters as plans continue to be redefined including the possibility that mining operations may not be sustained at the Gunnison Copper Project, risks related to the delay in approval of work plans, variations in mineral resources and reserves, grade or recovery rates, risks relating to the ability to access infrastructure, risks relating to changes in copper and other commodity prices and the worldwide demand for and supply of copper and related products, risks related to increased competition in the market for copper and related products, risks related to current global financial conditions, risks related to current global financial conditions on the Company's business, uncertainties inherent in the estimation of mineral resources, access and supply risks, risks related to the ability to access acid supply on commercially reasonable terms, reliance on key personnel, operational risks inherent in the conduct of mining activities, including the risk of accidents, labour disputes, increases in capital and operating costs and the risk of delays or increased costs that might be encountered during the construction or mining process, regulatory risks including the risk that permits may not be obtained in a timely fashion or at all, financing, capitalization and liquidity risks, risks related to disputes concerning property titles and interests, environmental risks and the additional risks identified in the "Risk Factors" section of the Company's reports and filings with applicable Canadian securities regulators.

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