Fortuna delivers robust Feasibility Study for the Diamba Sud Gold Project in Senegal: After-tax IRR of 60% and NPV5% of US$1 billion using US$3,500/oz

Fortuna Mining Corp. (NYSE: FSM | TSX: FVI) – https://www.commodity-tv.com/ondemand/companies/profil/fortuna-mining-inc/ – announces positive results from the feasibility study (“FS”) for its Diamba Sud Gold Project in Senegal, confirming an economically robust open-pit conventional carbon-in-leach (“CIL”) gold mine and advancing one of Fortuna’s key growth opportunities.

Jorge A. Ganoza, President and CEO of Fortuna, commented, “Diamba Sud is a standout growth project with high returns, fast payback, and is expected to be our lowest-cost mine. Together with our Séguéla mine expansion, Diamba Sud supports our plan to grow our annual gold production rate by approximately 60% to more than 500,000 ounces in 2028.” Mr. Ganoza concluded, “With the recent receipt of the environmental decree from the Senegalese government and the feasibility study complete, we are ready to move Diamba Sud toward a final investment decision upon completion of the mining permit process.”

Feasibility Study Highlights 

Financial

• After-tax NPV_5% of $1 billion, IRR of 60%, and 1-year payback at $3,500/oz gold
• At $4,000/oz gold, returns increase to NPV_5% of $1.3 billion, IRR of 72%, and 11-month payback 

Production and Cost

• Strong first 4 years: Average annual gold production of 158,000 ounces
• 9.4-year life of mine (“LOM”) with an average annual gold production of 116,000 ounces
• Low-cost profile: Average AISC¹ of $1,056/oz over the first 4 years and $1,332/oz over LOM
• Final investment decision expected after receipt of the mining permit; first gold targeted by Q2 2028 

CAPEX and Funding

• Total initial capital of $397.5 million
• Funding secured by the Company´s strong cash flow generation and liquidity of over $800 million² 

Early Works

• The Company continues advancing camp construction, office facilities and new site access road
• A letter of intent (“LOI”) has been executed with African Power Services (“APS”) as the power station engineering, procurement, and construction (“EPC”) contractor to secure the heavy-fuel oil (“HFO”) and light-fuel oil (“LFO”) generators.
• Front-end engineering design (“FEED”) is being completed to support early procurement of critical-path equipment, including the SAG mill, to reduce project schedule risk 

Notes:

1. This is a non-IFRS  financial measure. The definition and purpose of this non-IFRS financial measure is included under the heading “Cautionary Note on Non-IFRS Measures” in this news release
2. Liquidity position as at March 31, 2026

Further information is attached.

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, Guinea, Guyana, 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.

Investor Relations:
Carlos Baca | info@fmcmail.com | fortunamining.com | X | LinkedIn | YouTube | Instagram | TikTok

In Europe
Swiss Resource Capital AG
Marc Ollinger
info@resource-capital.ch
www.resource-capital.ch

Cautionary Note Regarding Forward-Looking Statements

This news release contains forward-looking statements which constitute “forward-looking information” within the meaning of applicable Canadian securities legislation and “forward-looking statements” within the meaning of the “safe harbor” provisions of the Private Securities Litigation Reform Act of 1995 (collectively, “Forward-looking Statements”). All statements included herein, other than statements of historical fact, are Forward-looking Statements and are subject to a variety of known and unknown risks and uncertainties which could cause actual events or results to differ materially from those reflected in the Forward-looking Statements. Forward-looking Statements contained in this news release include, without limitation, statements with respect to: the Company’s expectation of increasing annual gold production by 60% and the anticipated timing thereof; the calculation of Mineral Resources and Mineral Reserves at the Project and the possibility of eventual economic extraction of minerals from the Project; the identification of future Mineral Resources at the Project; the Company’s ability to convert more of its existing Mineral Resources into categories of Mineral Resources or Mineral Reserves of increased geological confidence; the projected yearly gold production profile from open pit operations, all-in sustaining costs, mill throughput and average grades; future plans for exploration drilling; the projected economics of the Project, including margins, taxes, average annual production and costs, potential recovery rates, the net present value (NPV) of the Project, the internal rate of return (IRR) on the Project, project payback period, cash flow, mine life, the total initial capital and sustaining capital required, and closure costs; the project design, including the mining method, tailings storage facility, process plant, water storage dam, power sources, and stockpile establishment; the plans for completing the early works program; the project development timeline to production; the filing of the technical report supporting the FS; obtaining the exploitation permit and other permitting approvals, a final investment decision, and the development, construction and production at the Project; the timing of and future prospects for exploration and any expansion of the Project.

These statements are based on information currently available to the Company, and the Company provides no assurance that actual results will meet management’s expectations. In certain cases, Forward-looking Statements may be identified by such terms as "anticipates", "believes", "could", "estimates", "expects", "may", "shall", "will", or "would". Forward-looking Statements contained in this news release are based on certain factors and assumptions regarding, among other things, the FS, the estimation of Mineral Resources and Mineral Reserves and any potential upgrades thereof, gold metal prices, the timing and amount of future exploration and development expenditures, the estimation of initial and sustaining capital requirements, the estimation of labor and operating costs, the availability of necessary financing and materials to continue to explore and develop the Company’s properties in the short and long-term, the progress of exploration and development activities, the receipt of necessary regulatory approvals, the royalties, taxes payable, contributions to the social development fund etc. set out in the FS are based upon the provisions of the Mining Convention between Boya S.A. and the State of Senegal dated April 8, 2015. There can be no assurance that such provisions will not be renegotiated by the State as part of the exploitation permit approval process, and assumptions with respect to currency fluctuations, environmental risks, title disputes or claims, and other similar matters. The Company also notes that, the State of Senegal will assume a 10% free-carried ownership interest in the Project when an exploitation permit is granted and may elect to purchase up to an additional 25% contributory interest in Boya SA at a “fair price” as determined through an independent valuation. While the Company considers these assumptions to be reasonable based on information currently available to it, they may prove to be incorrect.

Although the Company believes the expectations expressed in such Forward-looking Statements are based on reasonable assumptions, such statements are not guarantees of future performance and actual results or developments may differ materially from those in the Forward-looking Statements. Factors that could cause actual results to differ materially from those in Forward-looking Statements include: changes in market conditions, unsuccessful exploration results, possibility of project cost overruns or unanticipated costs and expenses, changes in the costs and timing of the development of new deposits, inaccurate Mineral Resources and Mineral Reserves estimates, changes in the price of gold, unanticipated changes in key management personnel and general economic conditions; the duration and impacts of geo-political uncertainties on the Company’s production, workforce, business, operations and financial condition; the expected trends in mineral prices, inflation and currency exchange rates; that all required approvals and permits will be obtained for the Company’s business and operations on acceptable terms; that there will be no significant disruptions affecting the Company’s operations; whether the Senegalese Government’s royalty percentage may increase in the future; and whether the State of Senegal elects to purchase up to an additional 25% interest in Boya SA at a “fair price” as determined through an independent valuation. Mining exploration and development is an inherently risky business. Accordingly, actual events may differ materially from those projected in the Forward-looking Statements. This list is not exhaustive of the factors that may affect any of the Company’s Forward-looking Statements, including the factors included in the Company’s annual information form for the year ended December 31, 2025. These and other factors should be considered carefully, and readers should not place undue reliance on the Company’s Forward-looking Statements. Forward-looking Statements are made as of the date hereof, and the Company disclaims any obligation to update any Forward-looking Statements, whether as a result of new information, future events, or results or otherwise, except as required by law. There can be no assurance that these Forward-looking Statements will prove to be accurate, as actual results and future events could differ materially from those anticipated in such statements.

Cautionary Note to United States Investors Concerning Mineral Resources and Mineral Reserves

Technical disclosure regarding the Company’s properties included herein has been prepared in accordance with National Instrument 43-101, Standards of Disclosure for Mineral Projects ("NI 43-101") and the Canadian Institute of Mining, Metallurgy, and Petroleum Definition Standards on Mineral Resources and Mineral Reserves. Canadian standards, including NI 43-101, differ from the requirements of the Securities and Exchange Commission, and information included herein may not be comparable to similar information disclosed by U.S. companies.

Cautionary Note on Non-IFRS Measures

This news release includes certain terms or performance measures commonly used in the mining industry that are not defined under International Financial Reporting Standards (“IFRS”), including EBITDA, cash costs, and AISC. Non-IFRS measures do not have any standardized meaning prescribed under IFRS and, therefore, they may not be comparable to similar measures employed by other companies. We believe that, in addition to conventional measures prepared in accordance with IFRS, certain investors use this information to evaluate our performance. The data presented is intended to provide additional information and should not be considered in isolation or as a substitute for measures of performance prepared in accordance with IFRS. Readers should also refer to our management’s discussion and analysis for the three months ended March 31, 2026, which is available under our corporate profile on SEDAR+ at www.sedarplus.ca and on EDGAR at www.sec.gov/edgar for a more detailed discussion of how we calculate such measures.

All-in Sustaining Costs

The Company, in conjunction with an initiative undertaken within the gold mining industry, has adopted AISC and all-in sustaining cost measures based on guidance published by World Gold Council ("WGC"). The Company conforms its AISC and all-in cash cost definitions to that set out in the guidance and the Company has presented the cash cost figures on a sold ounce basis. We define All-in Sustaining Costs as total production cash costs incurred at the applicable mining operation but excludes mining royalty recognized as income tax within the scope of IAS12, as well as non-sustaining capital expenditures. Sustaining capital expenditures, corporate selling, general and administrative expenses, gains from blue-chip swaps and brownfield exploration expenditures are added to the cash cost. AISC is estimated at realized metal prices.

Cash Costs

Cash costs include all direct and indirect operating cash costs related directly to the physical activities of producing metals, including mining and processing costs, third-party refining and treatment charges, on-site general and administrative expenses, applicable production taxes and royalties which are not based on sales or taxable income calculations , net of by-product credits, but are exclusive of the impact of noncash items that are included as part of the cost of sales that is calculated in the consolidated Income Statement including depreciation and depletion, reclamation, capital, development and exploration costs.

Management believes that cash cost and AISC measures provide useful information regarding the Company’s ability to generate operating earnings and cash flows from its mining operations and uses such measures to monitor the performance of the Company’s mining operations. In addition, the Company believes that each measure provides useful information to investors in comparing, on a mine-by-mine basis, our operations relative performance on a period-by-period basis, against our competitors’ operations.

EBITDA

EBITDA is a non-IFRS measure which is calculated as net income before interest, taxes, depreciation, and amortization, and is an alternate measure of profitability to net income. Management believes it is used by investors and analysts as useful indicators of assessing a company’s profitability and financial performance.