Alamos Gold Inc. (TSX:AGI) (NYSE:AGI) reported new results from ongoing surface exploration drilling within the Mulatos District. Drilling continues to extend high-grade gold mineralization beyond Mineral Reserves at Puerto Del Aire, and Mineral Resources at Cerro Pelon. Additionally, drilling within a new area of focus at Halcon has intersected wide intervals of significant sulphide-hosted gold mineralization.

Cerro Pelon, Halcon and other targets across the District including La Yaqui Grande, represent upside to the PDA project as potential sources of additional higher-grade sulphide ore. The PDA project will include the construction of a mill to process higher-grade sulphide ore from PDA, opening up new opportunities to define and incorporate additional sulphide ore from across the District. PDA remains on track for initial production mid-2027.

“Over the past several years, our focus within the Mulatos District has shifted to targeting higher grade sulphide mineralization. Our long-term track record of exploration success has continued having defined more than a million ounces of Mineral Reserves at PDA, and an initial Mineral Resource at Cerro Pelon. Ongoing success over the past year is expected to drive further Resource growth at Cerro Pelon, and resulted in a new discovery at Halcon, highlighting both the significant upside opportunities to the PDA project, and tremendous exploration potential across the Mulatos District,” said John A. McCluskey, President and Chief Executive Officer.

Cerro Pelon: step-out drilling below and north of the previously mined oxide deposit continues to intersect significant high-grade mineralization, extending and defining new structurally controlled feeder structures. This is expected to drive further growth in higher-grade Mineral Resources. Cerro Pelon is located nine kilometres (“km”) by road from the planned PDA mill and represents a potential source of additional high-grade mill feed. New highlights include¹:

• 5.60 g/t Au over 23.85 m (25PEL107);
• 5.85 g/t Au over 17.35 m (5.93 m true width) (24PEL081);
• 6.58 g/t Au over 15.15 m (25PEL127);
• 6.64 g/t Au over 12.05 m (8.67 m true width) (25PEL109);
• 4.28 g/t Au over 14.10 m (25PEL120);
• 4.08 g/t Au over 13.70 m (25PEL157);
• 12.95 g/t Au over 4.25 m (25PEL142);
• 6.13 g/t Au over 7.20 m (25PEL156); and
• 6.49 g/t Au over 6.05 m (2.75 m true width) (25PEL108).

PDA: drilling continues to extend high-grade gold mineralization beyond existing Mineral Reserves and Resources. Limited drilling was completed in 2025 at PDA with the focus shifting to construction of the project. Exploration drilling will resume from underground as development advances and drill platforms are established. New highlights include²:

• 13.64 g/t Au over 8.97 m (24MUL397);
• 3.72 g/t Au over 15.60 m (24MUL398);
• 4.27 g/t Au over 15.61 m (25MUL422);
• 4.85 g/t Au over 14.92 m (24MUL403);
• 8.79 g/t Au (6.90 g/t Au cut) over 6.92 m (25MUL411);
• 5.77 g/t Au over 7.10 m (25MUL418);
• 15.00 g/t Au over 2.91 m (24MUL395); and
• 43.70 g/t Au (40.00 g/t Au cut) over 0.81 m (24MUL397).

Halcon Target: wide intervals of significant sulphide-hosted gold mineralization intersected within a new discovery. Halcon represents another potential source of higher-grade sulphide mineralization and mill feed, located approximately 2 km north of the La Yaqui Grande open pit, and 7 km by road from the main Mulatos area. New highlights include³:

• 3.04 g/t Au over 47.60 m (25HAL017) including;
  • 7.78 g/t Au over 4.50 m;
  • 6.73 g/t Au over 2.10 m; and
  • 13.41 g/t Au over 3.75 m.
• 3.53 g/t Au over 37.35 m (25HAL025) including;
  • 8.13 g/t Au (7.82 g/t Au cut) over 10.20 m.
• 3.46 g/t Au over 31.50 m (25HAL019) including;
  • 5.56 g/t Au over 6.00 m; and
  • 4.35 g/t Au over 21.00 m.
• 3.88 g/t Au over 19.00 m (25HAL024) including;
  • 10.08 g/t Au over 3.40 m; and
  • 5.90 g/t Au over 5.50 m.

¹Composite widths for Cerro Pelon are core length. Where possible, estimated true width is provided.

²Composite widths for PDA are estimated true width of the mineralized zones. Drillhole composite gold grades reported as “cut” at PDA include higher grade samples which have been cut to 40 g/t Au.

³Composite widths at Halcon are core length as true width is unknown at this time. Drillhole composite gold grades reported as “cut” at Halcon include higher grade samples which have been cut to 40 g/t Au.

New highlight intercepts can be found in Table 1, and in Figures 2 through 5 at the end of this news release.

2025 Exploration Program – Mulatos District

A total of $20 million was spent on exploration in the Mulatos District in 2025, similar to spending in 2024. The near-mine and regional drilling program totalled 56,117 m in 170 holes. This included 13,779 m of surface exploration drilling in 58 holes at the GAP-Victor and PDA targets at PDA, and 21,394 m in 56 holes at Cerro Pelon. Regional exploration drilling totalled 20,944 m in 56 holes focused on advanced and greenfield targets within the Mulatos District. The Halcon discovery was made as part of the regional exploration drilling program where scout drilling tested a new geological interpretation of the area.

PDA is a higher-grade underground deposit located adjacent to the main Mulatos pit (Figure 1). The results of a positive internal economic study were announced in September 2024 and highlighted an attractive, low-cost, high-return project. With the amendment to the environmental permit received in 2025, construction activities have been ramping up with first production anticipated mid-2027.

The planned addition of a mill to process higher-grade sulphides has created new opportunities for growth within the Mulatos District. This includes Cerro Pelon, where drilling in 2024 was successful in defining an initial Measured and Indicated Mineral Resource at Cerro Pelon totaling 104,000 ounces, grading 4.49 g/t Au. Cerro Pelon remains open in multiple directions and represents upside to the PDA project, with the deposit within trucking distance of the planned mill.

Cerro Pelon

The 2025 drill program at Cerro Pelon was focused on continuing to define and expand high-grade mineralization below and to the north of the previously mined open pit where wide, high-grade mineralization was intersected across multiple drill holes between 2008 to 2017.

High-grade gold and silver mineralization is localized along and at the intersection of north north-west structures, and east north-east structures, thought to represent high sulphidation feeder zones (Figure 2 and 3). Ongoing drilling is expected to refine the structurally controlled zones. There is significant potential to expand the mineralization in all directions as demonstrated by the results from the most northerly two areas of the deposit. A total of 21,394 m of drilling was completed in 2025. New highlights from this drilling include¹:

• 5.60 g/t Au over 23.85 m (25PEL107);
• 5.85 g/t Au over 17.35 m (5.93 m true width) (24PEL081);
• 6.58 g/t Au over 15.15 m (25PEL127);
• 6.64 g/t Au over 12.05 m (8.67 m true width) (25PEL109);
• 4.28 g/t Au over 14.10 m (25PEL120);
• 4.08 g/t Au over 13.70 m (25PEL157);
• 12.95 g/t Au over 4.25 m (25PEL142);
• 6.13 g/t Au over 7.20 m (25PEL156); and
• 6.49 g/t Au over 6.05 m (2.75 m true width) (25PEL108).

¹Composite widths for Cerro Pelon are core length. Where possible, estimated true width is provided.

PDA

PDA is a higher-grade underground deposit located adjacent to the main Mulatos pit and is comprised of multiple mineralized zones including PDA, Gap, Victor, and Estrella (Figure 4). The focus of the 2025 surface exploration program was building upon the successful growth of the deposit over the last several years, including a 9% increase in the year end 2024 Mineral Reserves to 1.1 million ounces, grading 5.45 g/t Au.

In 2025, 2,988 m of drilling was completed within the GAP-Victor zones, and in the relatively untested area between the PDA zones and GAP-Victor. Another 9,618 m of drilling was completed at PDA with the goal of Mineral Resource expansion. Drilling continues to extend high-grade mineralization beyond existing Mineral Reserves; however, limited drilling was completed in 2025 with the focus shifting to construction of the project.

Exploration and Mineral Resource Expansion drilling will recommence at PDA once underground drill platforms have been established to allow for more efficient exploration drill testing below unmineralized cover rock. With the deposit open in multiple directions, there is excellent potential for PDA to continue to grow. Over the past four years, discovery costs at PDA have averaged $19 per ounce.

New highlights from results received since the year end 2024 Mineral Reserves and Resources include²:

• 13.64 g/t Au over 8.97 m (24MUL397);
• 3.72 g/t Au over 15.60 m (24MUL398);
• 4.27 g/t Au over 15.61 m (25MUL422);
• 4.85 g/t Au over 14.92 m (24MUL403);
• 8.79 g/t Au (6.90 g/t Au cut) over 6.92 m (25MUL411);
• 5.77 g/t Au over 7.10 m (25MUL418);
• 15.00 g/t Au over 2.91 m (24MUL395); and
• 43.70 g/t Au (40.00 g/t Au cut) over 0.81 m (24MUL397).

²Composite widths for PDA are estimated true width of the mineralized zones. Drillhole composite gold grades reported as “cut” at PDA include higher grade samples which have been cut to 40 g/t Au.

Halcon Target

Drilling commenced in the eastern portion of the Halcon target area early in 2025 as part of the regional scout drilling program (Figure 5). Drilling initially tested a new geological interpretation in an area that had only tested near-surface gold mineralization associated with oxides. As exploration drilling advanced, wide intervals of significant sulphide-hosted gold mineralization were intersected within a new area of focus at Halcon. The mineralized hydrothermal breccia is currently interpreted to dip to the northeast, and gold intercepts range from 38 m below surface in the west, to 282 m below surface down dip to the northeast. Mineralization remains open to the north, south and down dip.

The Halcon target is located 2 km north of the La Yaqui Grande open pit and 7 km by road from the main Mulatos area. This new discovery is being targeted and evaluated as a potential additional source of sulphide mineralization to be processed within the PDA mill. New highlights include³:

• 3.04 g/t Au over 47.60 m (25HAL017) including;
  • 7.78 g/t Au over 4.50 m;
  • 6.73 g/t Au over 2.10 m; and
  • 13.41 g/t Au over 3.75 m.
• 3.53 g/t Au over 37.35 m (25HAL025) including;
  • 8.13 g/t Au (7.82 g/t Au cut) over 10.20 m.
• 3.46 g/t Au over 31.50 m (25HAL019) including;
  • 5.56 g/t Au over 6.00 m; and
  • 4.35 g/t Au over 21.00 m.
• 3.88 g/t Au over 19.00 m (25HAL024) including;
  • 10.08 g/t Au over 3.40 m; and
  • 5.90 g/t Au over 5.50 m.
• 7.08 g/t Au over 6.35 m (25HAL047); and
• 3.54 g/t Au over 7.75 m (25HAL046).

³Composite widths at Halcon are core length as true width is unknown at this time. Drillhole composite gold grades reported as “cut” at Halcon include higher grade samples which have been cut to 40 g/t Au.

Qualified Persons

Scott R.G. Parsons, P.Geo., FAusIMM, Alamos Gold’s Vice President, Exploration, has reviewed and approved the scientific and technical information contained in this news release. Scott R.G. Parsons is a “Qualified Person” as defined by Canadian Securities Administrators’ National Instrument 43-101 – Standards of Disclosure for Mineral Projects.

Exploration programs at Mulatos are directed and supervised by Michele Cote, P.Geo., Alamos Gold’s Chief Exploration Geologist, Corporate. Michele Cote is a “Qualified Person” as defined by Canadian Securities Administrators’ National Instrument 43-101 – Standards of Disclosure for Mineral Projects.

Quality Assurance and Quality Control

Alamos Gold maintains an internal Quality Assurance / Quality Control (QA/QC) program at Mulatos to ensure sampling and analysis of all exploration work is conducted in accordance with best practices.

Access to the Mulatos Property is controlled by security personnel. The drill core is logged and sampled at the core logging facility within the mine site under the supervision of a Qualified Geologist. A geologist marks the individual samples for analysis, and sample intervals, based on lithology and alteration, standards and blanks are entered into the database. The core is cut in half using an electric core saw equipped with a diamond tipped blade. One half of the core is placed into a micropore sample bag and sealed with a cable tie in preparation for shipment. The other half of the core is returned to the core box and retained for future reference. The samples are placed in large heavy-duty nylon reinforced micropore bags, which are identified and sealed before being dispatched. The core samples are picked up at the mine site and delivered to Bureau Veritas Commodities Canada Ltd. laboratory in Hermosillo, Mexico.

Gold is analyzed by 30 grams Lead Collection Fire Assay Fusion (FA) that ends with an Atomic Absorption Spectroscopy finish (AAS). Samples greater than 5.0 g/t Au are re-analyzed starting again with a FA process but ending with a gravimetric finish. Bureau Veritas is an ISO/IEC 17025 accredited laboratory and has internal quality control programs that include insertion of reagent blanks, reference materials, and pulp duplicates that are in line with normal requirements, as well as participating in yearly proficiency tests to evaluate lab performance.

The Corporation inserts QC samples (blanks and reference materials) at regular intervals to monitor laboratory performance. Cross check assays are completed on a regular basis in a secondary accredited laboratory.

About Alamos

Alamos is a Canadian-based intermediate gold producer with diversified production from three operations in North America. This includes the Island Gold District and Young-Davidson mine in northern Ontario, Canada, and the Mulatos District in Sonora State, Mexico. Additionally, the Company has a strong portfolio of growth projects, including the Phase 3+ Expansion at Island Gold, and the Lynn Lake project in Manitoba, Canada. Alamos employs more than 2,400 people and is committed to the highest standards of sustainable development.