Mr. Keith Bodnarchuk reports

COSA ANNOUNCES WINTER 2026 DRILLING PLANS FOR JOINT VENTURES WITH DENISON MINES

Cosa Resources Corp. has detailed drilling plans for the company's Darby and Murphy Lake North (MLN) projects. Darby and MLN are joint ventures between Cosa and Denison Mines Corp., and are located 10 kilometres west of Cameco's Cigar Lake mine and three kilometres east of IsoEnergy's Hurricane deposit, respectively, in the eastern Athabasca basin, Saskatchewan. Cosa is the operator of both projects and holds a 70-per-cent interest, with Denison holding a 30-per-cent interest in each.

Highlights:

• Drilling at Darby will directly follow up compelling historical results, including anomalous uranium content in the sandstone and weak uranium mineralization in the basement;
• Drilling at MLN will further evaluate the kilometre-scale structure and alteration zone at the Cyclone trend and an additional parallel trend to the south;
• Denison participating in financing 2026 exploration at MLN to maintain its 30-per-cent interest.

Keith Bodnarchuk, president and chief executive officer, commented: "Identification of additional drill ready targets proximal to historical intersections of uranium mineralization and under modest sandstone cover has added to our excitement to commence drilling at Darby. With support and participation from Denison, our joint venture partner and largest shareholder, we are fully funded and prepared for an exciting year of exploration at both Darby and Murphy Lake North. We thank Denison for their continued guidance and commitment to working towards exploration success at these projects. Camp construction is well under way and we expect drilling to commence at Darby next week."

Andy Carmichael, vice-president of exploration, commented: "Retention of high-quality data by Denison combined with the experience gained over the last 15 years has allowed us to identify what may be some of the last remaining high-calibre untested target areas near Cigar Lake. Darby hosts five historical intersections of mineralization proximal to untested structures across multiple trends. Our initial target areas have coincident untested structures, alteration and anomalous uranium content in the lower sandstone. At MLN, we are eager to continue testing large gaps in strike where compelling structure and alteration have been intersected by widely spaced drilling on the Cyclone trend. Evaluation of an additional trend south of Cyclone is also a priority objective for this winter. Our decision to prioritize targets under frozen lakes, combined with a property-wide DC resistivity survey planned for the spring, is aimed at identifying the most prospective targets for an expanded follow up campaign in the summer."

Darby winter drilling

Approximately 2,500 metres are planned at Darby in winter 2026 to begin testing the high-priority targets identified by Cosa's 2025 core relogging and reinterpretation program. High-priority targets are the immediate vicinities of drill holes, which intersected zones of coincident sandstone alteration and anomalous1 uranium content proximal to significant graphitic basement faults. Up to four initial target areas will be evaluated during winter 2026.

Gamma trend

The Gamma trend contains over four kilometres of conductive strike length. Only two of four historical drill holes at Gamma intersected conductive basement rocks and none intersected the optimal target. The trend is considered highly prospective based on the presence of anomalous sandstone uranium content proximal to graphitic basement faults and numerous intersections of uranium mineralization along trend immediately north of Darby.

Historical hole DB-17 intersected continuously elevated to anomalous uranium content in the basal 108 metres of sandstone with coincident clay alteration and bleached zones. Graphitic faults were intersected 45 and 55 metres below the unconformity. The intersection of these graphitic faults with the unconformity, proximal to highly anomalous uranium in the lower sandstone, is the initial follow up target at Gamma in winter 2026. Over 2.5 kilometres to the south, drill hole DB-22 intersected several intervals of elevated to anomalous sandstone uranium content above basement metasediments that were altered near the end of the drill hole. Follow-up of DB-22 is a priority target.

Charlie trend

DB-09, the westernmost drill hole at Charlie, intersected multiple zones of elevated to strongly anomalous uranium content in the lower 115 metres of sandstone. These intervals include continuously anomalous uranium over the basal 42 metres, illite and chlorite enrichment, bleached zones, and hydrothermal hematite. DB-09 intersected graphitic faults in the basement 30 to 60 metres below the unconformity. The intersection of these graphitic faults with the unconformity, proximal to strongly anomalous uranium in the lower sandstone, is a priority follow up target.

Delta trend

At Delta, the basal sandstone in DB-27 is pervasively bleached with illite and chlorite enrichment and includes a 48-metre interval of continuously anomalous uranium content. In the basement, DB-27 intersected 0.13 per cent U3O8 over 0.3 metre, 16 metres below the unconformity and graphitic faults 80 metres below the unconformity. The intersection of basement faulting with the unconformity is the initial target at the Delta trend.

For further details on the Charlie and Delta trends and targets, refer to Cosa's news release dated Oct. 14, 2025.

MLN winter drilling

Drilling plans at MLN comprise approximately 1,200 metres and will follow up summer 2025 results at the Cyclone trend, where broad zones of structure and alteration were intersected over a two-kilometre strike length. Winter drilling will target a 1,200-metre gap in drilling where a lake prevents summer access. Drilling will also follow up intensely graphitic rocks and faulting intersected deep in the basement of MLN25-007, where the primary target is the updip projection of this horizon to the unconformity. The target is interpreted to lie approximately 100 metres south of MLN25-007 and potentially represents an untested trend parallel to Cyclone.

Next steps

At Darby, camp construction is nearing completion and will be followed by mobilization of drilling equipment and personnel, with drilling expected to begin before the end of January. Cosa intends to use the winter access trail to mobilize supplies and equipment required for continued testing of high-priority targets planned for summer 2026.

At MLN, establishment of winter trails is continuing in advance of drilling planned to begin in March. During the program, Cosa plans to mobilize supplies and equipment to support property-wide DC resistivity surveying and a larger summer drilling program.

About Darby

Located 10 kilometres west of the Cigar Lake mine, Darby contains multiple prospective conductive trends and several historical intersections of weak uranium mineralization. Historical drilling demonstrates that many of these trends are highly prospective for uranium deposits characteristic of the eastern Athabasca basin, yet most of the strike length has not been effectively evaluated. Work by Cosa in 2025 prioritized these trends and identified several historical drill holes with results that suggest proximity to uranium mineralization (see Cosa's news release dated Oct. 24, 2025).

Darby was last drilled in 2009.

About Murphy Lake North

MLN covers a portion of the Larocque Lake trend and is located 2.7 kilometres east of the Hurricane deposit. Hurricane is the world's highest-grade indicated uranium resource and was discovered and delineated for IsoEnergy Ltd. by current members of Cosa's team. The Larocque Lake trend also hosts the high-grade Larocque Lake zone, Yelka prospect and Alligator Lake zone. MLN contains the along-strike extension of basement geology underlying the Hurricane deposit (the Hurricane trend), as well as a parallel conductive trend to the south (the Cyclone trend). Drilling by Cosa in 2025 intersected zones of sandstone alteration and structure associated with graphitic basement structures along both trends. Following up these positive results is the primary 2026 objective at MLN.

About Cosa Resources Corp.

Cosa Resources is a Canadian uranium exploration company operating in northern Saskatchewan. The portfolio comprises roughly 237,000 ha across multiple underexplored 100-per-cent-owned and Cosa-operated joint venture projects in the Athabasca basin region, the majority of which reside within or adjacent to established uranium corridors.

In January of 2025, the company entered a transformative strategic collaboration with Denison Mines that has secured access to several additional highly prospective eastern Athabasca uranium exploration projects. As Cosa's largest shareholder, Denison gains exposure to Cosa's potential for exploration success and its pipeline of uranium projects.

Cosa's award-winning management team has a record of success in Saskatchewan. In 2022, members of the Cosa team were awarded the AME Colin Spence Award for the discovery of the Hurricane uranium deposit. Cosa personnel led teams or had integral roles in the discovery of Denison's Gryphon deposit and held key roles in the founding of both NexGen and IsoEnergy.

The company's focus throughout 2026 is drilling at the Darby and MLN projects in the eastern Athabasca basin. Both projects are operated by Cosa and are 70/30 joint ventures between Cosa and Denison, respectively. Drilling at Darby will evaluate target areas with anomalous uranium, clay alteration and historical mineralization intersected nearby. Drilling at MLN will follow up 2025 drilling which intersected broad zones of structurally controlled alteration over roughly two kilometres of strike length.

Technical disclosure

Historical drilling and geophysical results for Darby and MLN were sourced from the Saskatchewan Mineral Assessment Database (SMAD). SMAD sources for Darby include file Nos. 74H14-0021, 74H14-0023, 74H15-0041, 74H15-0053, 74H15-0055, 74H15-0056, 74H15-0066, 74H15-0067, 74I02-0031, 74I02-0042, 74I02-0053, 74I02-0080, 74I02-0095 and MAW00516. Some confidential data and reports not presently available via SMAD were supplied to Cosa by Denison. SMAD sources for MLN and adjacent projects include file Nos. 64L05-0161, 64L05-0180, 74I-0060, 74I-0066, 74I-0067, 74I01-0114, 74I08-0056, 74I09-0053, 74I09-0057, 74I09-0061, 74I09-0064, 74I09-0066, 74I09-0071, 74I09-0077, 74I09-0079, 74I09-0087, 74I09-0088, 74I09-0090, 74I09-0091, 74I09-0092, 74I09-0098, MAW00510, MAW01939, MAW02327, MAW02599 and MAW02395. Data and reports related to the 2020 ground EM (electromagnetic) survey completed by Denison are not presently available via SMAD and were supplied to Cosa by Denison.

Verification of historical drilling results included confirming historical drill hole collar locations from air photos and ground checking selected collars with a hand-held GPS unit. Basement and lower sandstone sections from most historical drill holes were relogged in 2024 and 2025 by Cosa. For Darby, verification of geochemical results for drill holes completed between 2008 and 2010 was facilitated by the reissuance of analytical certificates to Cosa by the Saskatchewan Research Council (SRC). Cosa thanks the SRC for its valued assistance in increasing confidence in the historical data set.

Verification of historical geophysical results included confirming the locations of geophysical survey grids from air photos, compiling survey data and interpretations, and evaluating whether interpreted geophysical results could be reasonably explained by historical and current drilling results. For MLN, Cosa engaged a consultant to re-interpret historical geophysical surveys to validate selected previous interpretations.

Qualified person

The company's disclosure of technical or scientific information in this news release has been reviewed and approved by Andy Carmichael, PGeo, vice-president, exploration, for Cosa. Mr. Carmichael is a qualified person as defined under the terms of National Instrument 43-101. This news release refers to neighbouring properties in which the company has no interest. Mineralization on those neighbouring properties does not necessarily indicate mineralization on the company's properties.

We seek Safe Harbor.