Atha Energy Confirms Multiple High-Grade Discoveries Along the Mineralized Rib Corridor at Angilak Project - Assays from Rib East, West, And South Discoveries - All Holes Intersecting Uranium Mineralization, Grades Up To 5.55% U3O8

HIGHLIGHTS

• Assays confirm uranium mineralization across the Mineralized RIB Corridor ("MRC") at RIB South, East and West Discoveries, where results from twelve drillholes intersected uranium mineralization (Figures 2 & 3). These results are in addition to the previously announced RIB North Discovery, where the maiden drillhole, RIBN-DD-001, returned assays with 34.7 m of total composite uranium mineralization¹, including 13.6 m grading 0.53% U₃O₈, 1.1 m grading 4.81% U₃O₈, and grades up to 8.16% U₃O₈ over 0.5 m (See November 20^th, 2025, RIB North Assay Release);

RIB East Discovery

• Located on the 4.5 km long Eastern Limb of the MRC, ~1.4 km south of the significant RIB North Discovery (Figures 2 & 3);

• Currently defined by eight diamond drillholes over a 750 m strike length that remains open in all directions, with drilling highlighted by:

  • RIBE-DD-003 assays returned total composite uranium mineralization¹ of 8.6 m encompassing four zones from 101.4 m to 374.1 m (Figure 4), including a high-grade intersection² from 276.2 m to 277.3 m with 2.69% U₃O₈ over 1.1 m, including 5.55% U₃O₈ over 0.5 m;

  • RIBE-DD-007 assays returned total composite uranium mineralization¹ of 8.7 m encompassing six zones from 174.0 m to 215.3 m (Figure 5), including a higher-grade intersection from 207.2 m to 211.3 m with 0.236% U₃O₈ over 4.1 m, including 1.15% U₃O₈ over 0.5 m;

RIB West Discovery

• Located on the 4.0 km long Western Limb of the MRC, ~1.8 km southwest of the significant RIB North Discovery (Figures 2 & 3);

• Currently defined by three diamond drillholes over a 2.2 km strike length that remains open in all directions, with drilling highlighted by:

  • RIBW-DD-001 assays returned total composite uranium mineralization¹ of 1.7 m from 393.5 m to 395.2 m (Figure 6) with an average grade of 0.78% U₃O₈, including a high-grade intersection² with 1.36% U₃O₈ over 0.6 m;

  • RIBW-DD-003 assays returned total composite uranium mineralization¹ of 2.0 m from 234.2 m to 236.2 m (Figure 7) with an average grade of 0.291% U₃O₈, including a high-grade intersection² of 1.07% U₃O₈ over 0.5 m;

RIB South Discovery

• Located on the 4.5 km long Eastern Limb of the MRC, ~2.25 km south of the RIB East Discovery (Figures 2 & 3);

• Currently defined by one diamond drillhole, with prospective strike length open and untested in all directions along the MRC, with drilling highlighted by:

  • RIBS-DD-001 assays returned total composite uranium mineralization¹ of 2.0 m encompassing two zones from 158.5 m to 252.1 m (Figure 8), including 1.5 m from 250.6 m to 252.1 m with an average grade of 0.11% U₃O₈;

Mineralized RIB Corridor

• Mineralized RIB Corridor - 12 km corridor containing stacked graphitic shear zones, identified using 3D EM Inversion modeling. During the 2025 Angilak Exploration Program these EM anomalies were drill tested, resulting in a 100% success rate of intersecting uranium mineralization associated with graphitic shear zones, and the discovery of four new mineralized areas: RIB East, West, North and South, in addition to the historic RIB Discovery³ (Figures 2 & 3);

• Uranium mineralization discovered along the MRC consists of Athabasca styles of mineralization including basement, sandstone, and unconformity hosted mineralization;

• The MRC remains open within all discovery areas and is currently constrained only by a lack of additional MMT survey data south of the Historic RIB Discovery. Additional MMT surveys paired with 3D EM Inversion modeling is planned for 2026, designed to unlock and define the true scale and significance of the MRC and the entirety of the Angikuni Basin;

• Additional drill core samples from the KU Discovery, Mushroom Lake, and the Lac 50 Deposit area have been submitted to the Saskatchewan Research Council (SRC) Geoanalytical Laboratory for analysis. The Company anticipates disclosing all remaining assay results in the coming weeks.

Troy Boisjoli, CEO commented: "Since acquiring the Angilak Uranium Project in 2024 ATHA has completed two successful drill campaigns comprising 46 holes across the Lac 50 Deposit and RIB-Nine Iron trends - 45 of those holes have intersected uranium mineralization. The 2024 Angilak Exploration Program focused on the Lac 50 Deposit Trend, testing the envelop of mineralization with large step outs, culminating in release of an Exploration Target for the Lac 50 Deposit area - which remains completely open and unconstrained.

During the 2025 Program, our goal was to start to unlock the regional potential of Angilak. Testing new targets which had been derisked through our systematic exploration approach, utilizing all the tools at our disposal to drill test in the most cost-effective means possible. The assay results from the Mineralized RIB Corridor, hitting uranium mineralization on 100% of the holes drilled along the 12-km MRC speaks for itself. The success we've had at RIB demonstrates to us that the scale of the MRC is something truly special, and may represent one of the most significant emerging uranium regions in Canada."

Cliff Revering, VP Exploration added: "The Mineralized RIB Corridor continues to deliver compelling results, supported by the latest confirmation assays from the 2025 exploration program. Uranium mineralization encountered to date, spanning a 12 km structural corridor and anchored by the RIB North Discovery, demonstrates both scale and high-grade potential. Combined with the positive geological and geochemical signatures emerging from our 2025 work, the data increasingly points to a large mineralizing system.

Since acquiring the Angilak Project in 2024, ATHA's disciplined exploration strategy has consistently advanced discovery within the Angikuni Basin, leveraging targeted exploration tools that enhance efficiency and reduce risk of discovery. The delineation of the Mineralized RIB Corridor within the larger RIB-Nine Iron regional trend represents a significant new development and highlights just one of several high-upside targets across the basin.

As we look ahead to 2026, ATHA is well-positioned to build on this momentum. Our objective remains clear: to continue unlocking the value of this emerging uranium district and to demonstrate the long-term growth potential of the Angikuni Basin."

VANCOUVER, BC / ACCESS Newswire / December 10, 2025 / ATHA Energy Corp. (TSX.V:SASK)(FRA:X5U)(OTCQB:SASKF) ("ATHA" or the "Company"), is pleased to announce assay results from the remaining twelve holes drilled along the Mineralized RIB Corridor ("MRC"), completed as part of the 2025 Angilak Exploration Program at its 100%-owned Angilak Uranium Project in Nunavut, Canada (Figure 1). Assay results confirm uranium mineralization was intersected in all drillholes along the 12 km MRC, including the RIB East, West, and South Discoveries, in addition to the previously announced RIB North Discovery.

At the RIB East Discovery, a total of eight diamond drillholes were completed across a total strike length of 750 m and the area remains open in all directions. Drilling at RIB East is highlighted by RIBE-DD-003, assays returned total composite uranium mineralization¹ of 8.6 m encompassing four zones from 101.4 m to 374.1 m (Figure 4). This includes a high-grade² intersection from 276.2 m to 277.3 m with results returning an average grade of 2.69% U₃O₈ over 1.1 m, including 5.55% U₃O₈ over 0.5 m. At the RIB West Discovery, a total of three diamond drillholes were completed across a 2.2 km strike length, with the area remains open in all directions. Drilling at RIB West is highlighted by RIBW-DD-001 which returned total composite uranium mineralization¹ of 1.7 m from 393.5 m to 395.2 m (Figure 6) with an average grade of 0.78% U₃O₈, including a high-grade² intersection of 1.36% U₃O₈ over 0.6 m. RIB South is currently defined by one diamond drillhole, located ~ 2.25 km to the south of the RIB East Discovery. RIBS-DD-001 intersected total composite uranium mineralization¹ of 2.0 m encompassing two zones from 158.5 m to 252.1 m (Figure 8), including 1.5 m from 250.6 m to 252.1 m with an average grade of 0.11% U₃O₈.

The Mineralized RIB Corridor is a 12 km long corridor containing stacked graphitic shear zones, identified using 3D EM Inversion modeling. During the 2025 Angilak Exploration Program these EM anomalies were drill tested, resulting in a 100% success rate of intersecting uranium mineralization associated with the graphitic shear zones, and the discovery of four new mineralized areas: RIB East, West, North and South, in addition to the historic RIB Discovery³ (Figures 2 & 3). Uranium mineralization discovered along the MRC consists of Athabasca style mineralization including basement, sandstone, and unconformity hosted. The MRC remains open in all directions within the discovery areas with additional prospective strike length constrained only by a lack of additional MMT survey data south of the Historic RIB Discovery. Additional MMT surveys paired with 3D EM Inversion modeling is planned for 2026, designed to unlock and define the true scale and significance of the MRC and the entirety of the Angikuni Basin.

Detailed lithologic striplogs, including assay results tables, for all twelve holes can viewed in the Supplementary Release on ATHA Energy's website (Striplog Data).

Figure 1: Angilak Project Area - 2025 Exploration Target Area (Black Rectangles), Mineralized RIB Corridor (Red Rectangle), & Mapped Historic Mineralized Showings

Figure 2: 2025 Angilak Exploration Program - EM Inversion Model & Drill Collar Locations from MRC, along the RIB-Nine Iron Trend.

Figure 3: 2025 Angilak Exploration Program - Isometric schematic of the MRC, displaying EM Inversion model and 2025 drilling.

Table 1: 2025 Angilak Exploration Program Drill Collar Information