Mr. Jorge Ganoza reports

FORTUNA REPORTS 15% INCREASE YOY IN CONSOLIDATED MINERAL RESERVES AND UPDATES ESTIMATE OF SUNBIRD DEPOSIT, SÉGUÉLA

Fortuna Mining Corp. has provided updated consolidated mineral reserve and mineral resource estimates for its operating mines and projects in West Africa and Latin America. Fortuna successfully increased mineral reserves by 15 per cent year over year, after accounting for production related depletion. In addition, an updated estimate for Seguela as of March 31, 2026, reported an increase of 34 per cent in underground mineral reserves and a 55-per-cent increase in inferred mineral resources for the Sunbird deposit as a result of the successful infill and exploration drilling program executed in the second half of 2025. All dollar amounts in this news release are expressed in United States dollars, unless otherwise indicated.

Highlights of mineral reserve and mineral resource update

• Consolidated proven and probable mineral reserves are reported containing 3.0 million gold equivalent ounces (GEOs) representing a year-over-year increase of 15 per cent. Changes are due to the upgrading of resources to reserves representing 819,000 GEOs, primarily at Seguela, offset by production related depletion of 378,000 GEOs.
• Consolidated measured and indicated resources exclusive of mineral reserves are reported containing 2.1 million GEOs representing a year-over-year increase of 56 per cent. Primary drivers for the net increase are the result of drilling at Diamba Sud, upgrading 781,000 GEOs, a 165-per-cent increase, offset by the upgrading of resources to reserves at Seguela.
• Consolidated inferred mineral resources are reported containing 2.2 million GEOs representing a year-over-year increase of 4 per cent. The change is the result of drilling discovering 726,000 GEOs counteracting the impact of upgrading 628,000 GEOs.
• Underground mineral reserves for Seguela's Sunbird deposit are reported as 4.4 Mt (million tonnes) averaging 3.80 grams per tonne Au containing 539,000 ounces of gold, an increase of 34 per cent to its maiden estimate. Inferred mineral resources are reported as 2.9 Mt averaging 4.45 g/t Au containing 417,000 ounces of gold, a 55-per-cent increase.
• Diamba Sud's feasibility study remains on track for first-time reporting of mineral reserves in support of a construction decision by the end of this quarter.

Mineral reserves are estimated using a gold price of $2,300/oz and mineral resources are estimated using a gold price of $2,600/oz, except for the Diamba Sud project where mineral resources are estimated using a gold price of $3,300/oz.

Note: Gold equivalent ounces (GEOs) referred to in this news release are calculated using metal prices of $2,300/oz gold, $27/oz silver, $2,000/t lead and $2,700/t zinc.

Seguela mine, Ivory Coast -- underground mineral reserve gold ounces increase by 34 per cent

From Dec. 31, 2024, to March 31, 2026, proven and probable mineral reserve tonnes increased from 9.75 Mt to 16.36 Mt, up 68 per cent, while the gold grade decreased slightly from 3.38 grams per tonne to 3.01 g/t Au. Measured and indicated mineral resources, exclusive of mineral reserves, increased from 3.44 Mt to 5.65 Mt, up 64 per cent, with contained gold increasing by 73,000 ounces, or 18 per cent, while the gold grade decreased from 3.59 g/t to 2.58 g/t gold. Inferred mineral resource tonnes increased from 6.77 Mt to 9.99 Mt, up 48 per cent, while gold grade decreased by 4 per cent, resulting in an increase in contained gold of 261,000 ounces, or 42 per cent.

The company previously disclosed mineral reserves and resource estimates as at Dec. 31, 2025 (refer to Fortuna news release dated Jan. 20, 2026). Since that publication, mineral reserves have increased by 73,000 ounces of gold and inferred mineral resources have increased by 143,000 ounces of gold. These changes reflect the inclusion of 55 exploration drill holes totalling 29,442 metres at the Sunbird deposit, which supported the conversion of resources to reserves and extended known mineralization by a further 100 metres down plunge. The increase in mineral reserves was partially offset by the impact of grade control drilling at the Sunbird open pit and mining depletion at the Antenna, Ancien and Koula deposits associated with gold production in the first three months of 2026.

At Seguela, the 2026 Brownfields exploration budget is $12.2-million and includes approximately 69,000 metres of exploration drilling. Exploration programs are focused on additional resource conversion drilling primarily at the Sunbird underground project, infill and expansion drilling at the Kingfisher deposit, and continued target generation (refer to Fortuna news release dated Jan. 15, 2026). Lindero mine and Arizaro gold project, Argentina -- production-related depletion of mineral reserves results in 8-per-cent decrease in gold ounces.

As of Dec. 31, 2025, the Lindero mine has proven and probable mineral reserves of 64.4 Mt containing 1.1 Moz gold, in addition to measured and indicated mineral resources, exclusive of mineral reserves, of 28.7 Mt containing 403,000 ounces of gold, and inferred mineral resources of 29.3 Mt containing 434,000 ounces of gold. Year-over-year mining depletion resulted in a decrease in mineral reserves of 6.1 Mt containing 121,000 ounces of gold.

Infill drilling totalling approximately 6,000 metres is planned at Lindero to target inferred mineral resources located below the ultimate reserve pit shell. The program is designed to increase confidence in the geologic continuity of mineralization, with the objective of converting additional resources to reserves and extending the mine life.

As of Dec. 31, 2025, the Arizaro gold project has Inferred mineral resources of 32.9 Mt averaging 0.38 g/t Au and containing 402,000 ounces of gold, representing an increase of 3 per cent in contained gold ounces compared with the prior year, primarily as a result of a higher gold price assumption and corresponding adjustments to the pit shell.

The 2026 Brownfields exploration budget for Lindero is $3.7-million and includes approximately 11,000 metres of exploration drilling at Arizaro, focused on further testing and extending the 2.5-kilometre strike potential to the southwest and at depth (refer to Fortuna news release dated Jan. 15, 2026).

Caylloma mine, Peru -- mineral reserve and resources impacted by production related depletion and higher precious to base metal price ratios

Year-over-year, proven and probable mineral reserve tonnes decreased from 2.44 to 2.28 Mt. Silver grade increased by 9 per cent, while lead and zinc grades decreased by 11 per cent and 16 per cent, respectively. The primary drivers of the change in mineral reserves were production-related depletion, which resulted in a reduction of 556,000 tonnes or 43,000 GEOs; partially offset by the addition of 230,000 tonnes or 22,000 GEOs from new discoveries and the upgrading of inferred mineral resources at the Animas/Animas NE and Ramal Piso Carolina veins; and changes in commercial terms and metal prices, which added 140,000 tonnes or 4,000 GEOs. A change in the gold-to-silver and base metal ratio resulting from higher gold prices reduced mineral reserves by 47,000 GEOs.

Inferred mineral resource tonnes increased from 3.79 to 3.90 Mt, representing an increase of 3 per cent. Silver grade increased by 9 per cent, while lead and zinc grades decreased by 14 per cent and 9 per cent, respectively. The primary drivers of the change in mineral resources were due to the upgrading of resources to reserves as detailed above; a reduction of 0.25 Mt or 25,000 GEOs in indicated mineral resources due to changes in the geologic interpretation and cut-off grades; and adjustments to the geological interpretation including sterilization of isolated or narrow mineralization identified as non-economic, which reduced inferred mineral resources by 250,000 tonnes containing 38,000 GEOs. A change in the gold-to-silver and base metal ratio resulting from higher gold prices further reduced inferred mineral resources by 48,000 GEOs.

The 2026 Brownfields exploration program budget at Caylloma is $3.8-million and includes approximately 12,000 metres of diamond core drilling targeting extensions to ore shoots 3 and 4 in the Animas zone, along with continued exploration of several other near-mine anomalies (refer to Fortuna news release dated Jan. 15, 2026). Diamba Sud gold project, Senegal -- successful infill and exploration drilling drives 165-per-cent growth in indicated resource gold ounces

The company previously disclosed a preliminary economic analysis and updated mineral resource estimate as at Jan. 16, 2026 (refer to Fortuna news release dated Feb. 19, 2026). Year over year, measured and indicated mineral resources increased from 7.8 Mt to 26.0 Mt, representing an increase of 236 per cent, while gold grade decreased by 21 per cent, resulting in an increase of 781,000 ounces of gold or 165 per cent. Inferred mineral resource tonnes decreased from 3.1 Mt to 2.1 Mt, with gold grade decreasing by 23 per cent, resulting in a reduction of 71,000 ounces of gold, or 48 per cent, due to upgrading in resource classification as a result of infill drilling.

The company is advancing a feasibility study, including the estimation of mineral reserves, to support a construction decision by the end of the second quarter of 2026.

The 2026 Brownfields exploration budget at Diamba Sud is $8.8-million and includes approximately 35,000 metres of exploration drilling to support resource conversion drilling and continued target generation (refer to Fortuna news release dated Jan. 15, 2026).

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 No. 36328) and a qualified person as defined by National Instrument 43-01 -- 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 is a Canadian precious metals mining company with three operating mines and exploration activities in Argentina, Ivory Coast, Guinea, Guyana, Mexico and Peru, as well as the Diamba Sud gold project located in Senegal. Sustainability is integral to all the company's operations and relationships. Fortuna produces gold and silver and generate shared value over the long term for the company's stakeholders through efficient production, environmental protection and social responsibility.