Fortuna Mining Corp. (NYSE: FSM) (TSX: FVI) is pleased to announce updated Mineral Reserves and Mineral Resources excluding Mineral Reserves for the Séguéla Mine, reporting 1.2 million ounces of gold in Mineral Reserves, 794,000 ounces of gold in Indicated Resources, and 712,000 ounces of gold in Inferred Resources.

Jorge A. Ganoza, President and CEO, commented, “Continued exploration success over the last two years has created a clear pathway to not only extend the life of mine at Séguéla, but also to evaluate a further plant expansion and a potential increase in annual gold production.” Mr. Ganoza continued, “Séguéla now boasts a 7.5-year life of mine and its largest Mineral Resource inventory on record. In response, we have launched aggressive infill drilling programs, advanced underground mining studies, and initiated plant expansion evaluations to fully capture the opportunities created by our exploration success.” Mr. Ganoza concluded, “With robust exploration programs underway and continuing into 2026, we are confident in our ability to unlock further value from our commanding land position at Séguéla.”

Updated Mineral Reserves and Mineral Resources Highlights        

• Growth in Mineral Reserves offset production-related depletion, with an estimated 1.2 million ounces of gold, representing an 11% increase compared to December 31, 2024.
• Measured and Indicated Mineral Resources, exclusive of Mineral Reserves, are reported containing 794,000 ounces of gold, a 100% increase compared to December 31, 2024.
• Inferred Mineral Resources are reported containing 712,000 ounces of gold, reflecting a 15% increase compared to December 31, 2024.
• Kingfisher and Sunbird host the largest Mineral Reserves and Mineral Resources where mineralization remains open at both deposits.
• Completion of the underground mining study, supporting the potential conversion of up to 502,000 gold ounces of Sunbird Indicated Resources into Mineral Reserves, is expected in December 2025.
• Technical studies have been initiated to evaluate a plant expansion of approximately 25% capacity to between 2.0 and 2.5 million tonnes per year; studies are expected to be completed in the second quarter of 2026.

Mineral Reserves

Mineral Resources

Mineral Reserves 

As of October 31, 2025, the Séguéla Mine has Proven and Probable Mineral Reserves of 13.0 million tonnes containing 1.2 million ounces of gold.

From December 31, 2024, to October 31, 2025, Mineral Reserve tonnes increased by 33%, while gold grade decreased by 17% to 2.81 g/t Au, resulting in a net increase of 11% in contained gold ounces.

The reduction in the global reserve gold grade from 3.38 g/t Au to 2.81 g/t Au is a direct consequence of incorporating the Kingfisher deposit Mineral Reserves, while production during the period of January to October 2025 depleted higher grade material from the Koula and Ancien deposits. Although the Kingfisher deposit exhibits lower average grades relative to the high grade deposits, it benefits from a lower strip ratio of 7.6:1, compared to the average strip ratio of the Mineral Reserves of 13.4:1.

Changes in the Séguéla Mine’s Mineral Reserves are a result of:

• Mining-related depletion in the first ten months of 2025 totaling 129,000 ounces of gold.
• The first-time estimation of Mineral Reserves for the Kingfisher deposit, totaling 3.5 million tonnes at an average grade of 2.28 g/t Au containing 257,000 ounces of gold.
• Additional variations driven by an updated geologic interpretation of the Koula deposit, as a result of grade-control drilling, as well as adjustments to operational costs and gold price assumptions.

Mineral Resources

Measured and Indicated Mineral Resource gold ounces, exclusive of Mineral Reserves, increased by 100%, or 398,000 ounces. The change in Indicated Resources was driven by the growth in the Sunbird Underground Project which stands at 3.6 million tonnes averaging 4.34 g/t Au containing 502,000 gold ounces, an increase of 288,000 ounces compared to December 31, 2024. Changes were also a result of updating gold metal prices and pit optimizations to incorporate an additional 110,000 ounces of gold across all deposits.

Inferred Resources tonnage increased by 30% to 8.8 million tonnes, while gold grade decreased by 11% to 2.52 g/t, resulting in a net increase of 15% in contained gold to 712,000 ounces. The primary driver of this change was growth at the Kingfisher deposit, where most of the resources upgraded to Mineral Reserves were replaced by new Inferred Resources totaling 267,000 ounces of gold. Further contribution came from the Sunbird Underground Project where all upgraded Inferred Resources were replenished and an additional 53,000 ounces of gold added, bringing the total Inferred Resource to 1.7 million tonnes averaging 4.41 g/t Au containing 244,000 ounces of gold. Additional adjustments arose from updated gold price assumptions and the resulting open pit and underground mineable shape optimizations, which identified the potential for underground resources at Kingfisher.

Ongoing Exploration and Infill Drilling to Support Resource Growth

Drill activities remain ongoing across the Séguéla property, with five drill rigs currently active. Current drilling is focused on the potential for upgrading Inferred to Indicated Resources at the Sunbird Underground Project, while also evaluating mineralization potential at existing deposits and across the wider land package. However, insufficient tonnes were identified at the Gabbro North prospect to support a potentially economical open pit at this time.

Advancing Studies for Process Plant Expansion

Séguéla’s processing plant was commissioned in mid-2023 with a design throughput capacity of 156 t/hr, approximately 1.25 million tonnes per year. Since commissioning, several low-capital optimization initiatives have been implemented to enhance the efficiency of the plant, and the operation is now expected to treat 1.75 million tonnes per year beginning in 2026. Until recently, the increase in the mining rate required to sustain this higher throughput had been constrained by the mine life, which limited the rationale for investing in expanding the processing capacity.

The potential to extend mine life is supported by several key developments:

• Expansion of Mineral Resources at the Sunbird and Kingfisher deposits.
• Strong conversion of Inferred to Indicated Resources.
• Positive results from ongoing drilling of the Sunbird Underground Project completed after the June 30, 2025 data cut-off.
• Mineralization at both Kingfisher and Sunbird remains open in all directions.

Together, these factors provide increasing confidence in the potential to extend the mine life through future drilling and mining studies.

Given this improved visibility, Fortuna has initiated engineering studies to evaluate options for further expansion of processing plant capacity.

Sunbird Underground Project

Engineering work continues with the objective of converting Mineral Resources to Mineral Reserves by December 2025. All major technical studies, including among others, geotechnical, metallurgical, hydrogeological, are now complete, and the project team is currently developing the pre-feasibility report.

The Sunbird Underground Project has the potential to underpin strong Séguéla production for several years. Planned upcoming activities include:

• Updating Sunbird Underground Project Mineral Resources by year end.
• Ordering long-lead equipment for underground mining.
• Planning and execution of early works activities.
• Advancing government permitting.

Qualified Person

Eric Chapman, Senior Vice President, Technical Services, is a Professional Geoscientist of the Association of Professional Engineers and Geoscientists of the Province of British Columbia (Registration Number 36328) and a Qualified Person as defined by National Instrument 43-101- Standards of Disclosure for Mineral Projects. Mr. Chapman has reviewed and approved the scientific and technical information contained in this news release and has verified the underlying data.

About Fortuna Mining Corp.

Fortuna Mining Corp. is a Canadian precious metals mining company with three operating mines and a portfolio of exploration projects in Argentina, Côte d’Ivoire, Mexico, and Peru, as well as the Diamba Sud Gold Project in Senegal. Sustainability is at the core of our operations and stakeholder relationships. We produce gold and silver while creating long-term shared value through efficient production, environmental stewardship, and social responsibility. For more information, please visit our website at www.fortunamining.com.

ON BEHALF OF THE BOARD

Jorge A. Ganoza
President, CEO, and Director
Fortuna Mining Corp.

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