Fortuna Mining Corp. (NYSE: FSM) (TSX: FVI) is pleased to report encouraging first drilling results from the Kabewest prospect at its recently acquired Bambadji Project in Senegal. Kabewest is the most advanced drill-defined prospect at Bambadji and is located approximately 2.3 kilometers from the proposed Diamba Sud Gold Project plant site.

Paul Weedon, Senior Vice President of Exploration, commented, “The first holes at Kabewest have returned broad mineralized intervals, including 1.9 g/t Au over an estimated true width of 64 meters from 19 meters in drill hole FBRC0008. These results provide strong support for our geological interpretation and show clear similarities to the breccia-hosted mineralization at Diamba Sud,” Mr. Weedon continued, “With approximately 70 percent of assays received, the results to date continue to build confidence in the interpreted controls on mineralization and in Bambadji’s potential to expand Diamba Sud.” Mr. Weedon concluded, “We look forward to receiving the remaining assays in the coming weeks and incorporating the complete dataset into our work toward an initial Inferred Mineral Resource estimate, planned for publication in the first quarter of 2027.”

Kabewest Drilling Highlights

FBDD0001: 1.2 g/t Au over an estimated true width of 23 meters from 75 meters

FBDD0006: 1.8 g/t Au over an estimated true width of 29.5 meters from 393 meters

FBDD0008: 3.2 g/t Au over an estimated true width of 24 meters from surface, including 11.3 g/t Au over an estimated true width of 1.5 meters from 8 meters and 12.2 g/t Au over an estimated true width of 0.7 meters from 30 meters

FBDD0009: 1.4 g/t Au over an estimated true width of 22 meters from 65.5 meters, and 1.3 g/t Au over an estimated true width of 23 meters from 107 meters

FBRC0003: 3.1 g/t Au over an estimated true width of 24.2 meters from 4 meters, including 15.1 g/t Au over an estimated true width of 0.7 meters from 25 meters

FBRC0005: 1.4 g/t Au over an estimated true width of 29.6 meters from surface

FBRC0008: 1.9 g/t Au over an estimated true width of 64 meters from 19 meters, including 16.3 g/t Au over an estimated true width of 1.5 meters from 24 meters

The Bambadji Project is located immediately adjacent to the Diamba Sud Gold Project. The initial Kabewest drilling program, comprising 45 reverse circulation and diamond drill holes totalling 10,524 meters, has been completed. This work forms the first phase of a broader $8 million, 51,000-meter drilling program planned across the Bambadji Project through the end of 2026. The program is focused on at least eight priority prospects (refer to Figure 1 and Fortuna news release dated August 10, 2026, “Fortuna acquires highly prospective Bambadji Project in Senegal from Barrick and IAMGOLD”).

Figure 1: Bambadji Project: Location of priority exploration prospects and proximity to the Diamba Sud Gold Project proposed plant site

Broad mineralized intervals from the initial Kabewest drilling include 1.9 g/t Au over an estimated true width of 64 meters from 19 meters in drill hole FBRC0008 (refer to Figure 2), 1.4 g/t Au over an estimated true width of 29.6 meters in drill hole FBRC0005 (refer to Figure 3) and 3.1 g/t Au over an estimated true width of 24.2 meters from 4 meters in drill hole FBRC0003 (refer to Figure 4). These results strengthen the current geological interpretation and demonstrate geological continuity with the breccia-hosted mineralization at the nearby Diamba Sud deposits. Mineralization has been intersected over more than 600 meters of strike and remains open along strike and at depth, providing clear opportunities for systematic follow-up drilling.

Approximately 70 percent of assays have been received, with the balance expected in the coming weeks. Geological model updates are progressing and will incorporate the complete assay dataset to support preparation of an initial Inferred Mineral Resource estimate for Kabewest. Subject to completion and review of the remaining technical work, the Company expects to include the estimate in its annual Mineral Reserve and Mineral Resource update planned for publication in the first quarter of 2027.

Figure 2: Bambadji Project: Kabewest prospect, cross-section 350NE

Figure 3: Bambadji Project: Kabewest prospect, cross section 250NE

Figure 4: Bambadji Project: Kabewest prospect, cross section 50NE

As observed at Diamba Sud, mineralization at Kabewest is generally associated with hydrothermal breccia units, hematite-silica-altered limestone, and extensive pyrite development. These features reinforce the interpreted structural controls on gold-bearing fluids within the Falémé domain, which hosts both projects. The comparable geological features identified across the adjacent Diamba Sud and Bambadji Project support continued systematic exploration along the Senegal-Mali Shear Zone.

Following completion of the initial phase of Kabewest drilling, the six drill rigs have been relocated to the Wari and Latifa prospects (refer to Figure 1), where three drill rigs at each prospect are testing areas defined by historical, widely spaced reconnaissance drilling. Work is also progressing to refine targets for the 2027 field season using geochemical and geophysical data across more than 60 kilometers of strike within the Bambadji Project, where three mineralized trends have been identified. Historical drilling along these trends is generally shallow and widely spaced, leaving several multi-kilometer gaps that provide priority areas for evaluation as part of Fortuna’s 2026 and 2027 exploration programs.

Quality Assurance & Quality Control 

All drilling data completed by the Company utilized the following procedures and methodologies. All drilling was carried out under the supervision of the Company’s personnel.

All reverse circulation drilling used a 5.25-inch face sampling pneumatic hammer with samples collected into 60-liter plastic bags. Samples were kept dry by maintaining enough air pressure to exclude groundwater inflow. If water ingress exceeded the air pressure, RC drilling was stopped, and drilling converted to diamond core tails. Once collected, RC samples were riffle split through a three-tier splitter to yield a 12.5 percent representative sample for submission to the analytical laboratory. The residual 87.5 percent samples were stored at the drill site until assay results were received and validated. Coarse reject samples for all mineralized samples corresponding to significant intervals are retained and stored on-site at the Company-controlled core yard.

All diamond drilling drill holes started with HQ sized diameter, before reducing to NQ diameter diamond drill bits on intersecting fresh rock. The core was logged, marked up for sampling using standard lengths of one meter or to a geological boundary. Samples were then cut into equal halves using a diamond saw. One half of the core was left in the original core box and stored in a secure location at the Company core yard at the project site. The other half was sampled, catalogued, and placed into sealed bags and securely stored at the site until shipment.

All RC and DD samples were transported by Company vehicle or commercial courier to ALS Global’s preparation laboratories in Kedougou, Senegal with prepared sample pulps then transported via commercial courier to ALS Global’s analytical facility in Ouagadougou, Burkina Faso. Routine gold analysis using a 50-gram charge and fire assay with an atomic absorption finish was completed for all samples. Samples returning assays >10 ppm Au were reanalyzed using a 50-gram charge and fire assay with a gravimetric finish. Quality control procedures included the systematic insertion of blanks, duplicates and sample standards into the sample stream. In addition, the ALS Global laboratory inserted its own quality control samples.

Qualified Person

Paul Weedon, Senior Vice President, Exploration for Fortuna Mining Corp., is a Qualified Person as defined by National Instrument 43-101 and is a member of the Australian Institute of Geoscientists (Membership No. 6001). Mr. Weedon has reviewed and approved the scientific and technical information contained in this news release. He has verified the disclosed data, including the sampling, analytical and test data underlying the information and opinions herein, through review of the geochemical and geological databases and diamond drill core. There were no limitations on the verification process.

About Fortuna Mining Corp.

Fortuna Mining Corp. is a Canadian precious metals mining company with three operating mines in Argentina, Côte d’Ivoire, and Peru, and the feasibility-stage Diamba Sud Gold Project in Senegal. Our exploration portfolio spans our operating jurisdictions as well as Guinea and Guyana. 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
CEO, and Director
Fortuna Mining Corp.

Investor Relations:

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Appendix 1: Bambadji Project drill program details of the drill holes and assay results

Notes:
1. EOH: End of hole
2. Depths and widths reported to nearest significant decimal place
3. NSI: No significant intercepts
4. ETW: Estimated true width
5. RC: reverse circulation drilling | DD: diamond drilling