Fortuna Mining Corp. (NYSE: FSM) (TSX: FVI) is pleased to announce updated Mineral Reserves and Mineral Resources, excluding Mineral Reserves, for the Séguéla Mine as of December 31, 2025. Mineral Reserves total 1.54 million ounces of gold, reflecting the inclusion of 401,000 ounces of gold planned for underground mining at the Sunbird deposit.

Jorge A. Ganoza, President and CEO, commented, “Séguéla’s mine life now exceeds 9 years at current production rates, with strong potential for further growth. This is supported by exploration drilling completed in the second half of 2025, the results of which have not yet been incorporated into our geological resource models.” Mr. Ganoza added, “Building on this exploration upside and our track record of resource and reserve growth, we have initiated a processing plant expansion study that has the potential to increase annual gold production to more than 200,000 ounces.”

Updated Mineral Reserves and Mineral Resources Highlights

• Total Mineral Reserves of 16.0 million tonnes averaging 3.01 g/t Au, supporting a mine life of over 9 years at the current mining rate of 1.75 million tonnes per annum.

• Growth in Mineral Reserves more than offset production-related depletion, totaling approximately 1.54 million ounces of gold, representing a 31% increase compared to October 31, 2025.

• First time estimation of underground Mineral Reserves at Sunbird, comprising 3.5 million tonnes averaging 3.60 g/t Au and containing 401,000 ounces of gold.

• Exploration drilling completed in 2025 indicates that mineralization at the Sunbird deposit remains open down plunge and down dip, with an updated estimate planned for Q2 2026.

• Drilling at Kingfisher, Koula, and Ancien deposits demonstrates that mineralization remains open at depth, providing additional potential for further underground mining expansion.

• Technical studies are progressing to evaluate the optimal plant expansion, anticipated to increase capacity by approximately 25% to between 2.0 and 2.5 million tonnes per year, with studies on track for completion in Q2 2026.

Mineral Reserves

Mineral Resources

Notes:

1. Mineral Reserves and Mineral Resources are defined in accordance with the 2014 CIM Definition Standards for Mineral Resources and Mineral Reserves.
2. Mineral Resources are exclusive of Mineral Reserves.
3. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.
4. Factors that could materially affect the reported Mineral Resources or Mineral Reserves include changes in metal price and foreign exchange assumptions; changes in local interpretations of mineralization; changes to assumed metallurgical recoveries, mining dilution, and mining recovery; and assumptions regarding continued ability to access the site, retention of mineral and surface rights titles, maintenance of environmental and other regulatory permits, obtaining Ministerial approval to include underground mining as a mining method; and obtaining approval to update its Environmental and Social Impact Assessment permit to include underground mining; and the social license to operate.
5. Mineral Resources and Mineral Reserves are reported as of December 31, 2025.
6. Mineral Reserves are reported on a 100% ownership basis and estimated using incremental gold grade cut-offs for open pit mining of 0.73 g/t Au for Antenna and Koula, 0.74 g/t Au for Sunbird, 0.75 g/t Au for Boulder and Kingfisher, 0.76 g/t Au for Agouti, and 0.83 g/t Au for the Ancien and Badior deposits, and for underground mining of 2.14 g/t for Sunbird. These estimates are based on a gold price of $2,300/oz, metallurgical recovery rates of 93.5%, except for Badior at 91.5%, surface mining costs ranging from $3.09/t to $5.74/t based on the pit location relative to the run-of-mine pad, underground mining cost of $84.56/t, processing costs of $21.28/t, general and administrative (G&A) costs of $16.21/t. Only Proven and Probable Mineral Reserves within the final pit designs are reported. Antenna, Ancien, Koula, Badior and Kingfisher pits were designed with inter-ramp angles of 30.6° to 40.7° for oxide material, 40.7° to 42.9° for transitional material, and 59.6° for fresh material. Agouti and Boulder pits were designed with inter-ramp angles of 36.8° for oxide, 44.2° for transitional, and 60.0° for fresh material. Sunbird pit was designed with inter-ramp angles of 40.7° for oxide, 36.5° to 59.6° for transitional, and 52.2° to 61.2° for fresh material. For underground mining, a dilution factor of 0.5-meter skin has been applied on both the hanging wall and footwall for longhole stoping. The reported Mineral Reserves incorporate modifying factors for mining dilution and recovery through regularization of block models to an appropriate Selective Mining Unit (SMU) block size. Mineral Resources for the Séguéla Mine are reported at gold grade cut-offs of 0.65 g/t Au for Antenna, 0.66 g/t Au for Kestrel, Boulder, Sunbird, and Kingfisher; 0.68 g/t Au for Agouti; and 0.73 g/t Au for Ancien and Badior. These estimates are based on an assumed gold price of $2,600/oz and are constrained within preliminary pit shells honoring all geotechnical parameters. Underground Mineral Resources are reported within optimized stope shapes based on a longhole stoping mining method at cut-off grades of 1.89 g/t Au for Sunbird, 2.32 g/t Au for Koula and Kingfisher, and 2.41 g/t Au for Ancien. The Séguéla Mine is subject to a 10% free-carried interest held by the State of Côte d’Ivoire.
7. Eric Chapman, P. Geo. (EGBC #36328), is the Qualified Person responsible for Mineral Resources; and Raul Espinoza (FAUSIMM (CP) #309581) is the Qualified Person responsible for Mineral Reserves, both being employees of Fortuna Mining Corp.
8. Totals may not add due to rounding.

Mineral Reserves

As of December 31, 2025, the Séguéla Mine has Proven and Probable Mineral Reserves of 16.0 million tonnes containing 1.54 million ounces of gold.

Between October 31, 2025, and December 31, 2025, Mineral Reserve tonnes increased by 23%, while the average gold grade increased by 7% to 3.01 g/t Au, resulting in a net increase of 31% in contained gold ounces.

Changes in the Séguéla Mine’s Mineral Reserves during this period reflect:

• Mining-related depletion during the final two months of 2025 totaling 27,600 ounces of gold.

• The first-time estimation of underground Mineral Reserves at the Sunbird deposit, totaling 3.5 million tonnes at an average grade of 3.60 g/t Au, containing 401,000 ounces of gold.

Mineral Resources

Measured and Indicated Mineral Resource gold ounces, exclusive of Mineral Reserves, decreased by 333,000 ounces of gold due to the application of modifying factors that enabled the first-time estimation of underground Mineral Reserves.

Inferred Resources remained relatively unchanged compared to October 31, 2025.

Plant Expansion Study

Fortuna has commenced a processing plant expansion study to evaluate the potential to increase throughput at Séguéla beyond its current capacity of 1.75 Mtpa to a range of 2.0 to 2.5 Mtpa. The study is expected to be completed in the second quarter of 2026 and has the potential to support annual gold production in excess of 200,000 ounces.

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.