ATHA Energy Closes over-Subscribed Bought Deal – Makes Third New Discovery of 2025 Exploration Program at Rib West and Continues to Expand Mineralization at Rib East

HIGHLIGHTS

• ATHA closes previously announced CAD $11.5 Million Over-Subscribed Bought Deal (See

detail below, “Underwritten Private Placement”);

• First two drill holes completed at the RIB West Discovery successfully intersected uranium

mineralization, including high-grade, over a strike length of ~340 m (Figure 2);

• Results represent the third new discovery of uranium mineralization – beyond the Lac 50

Deposit Trend – during the 2025 Angilak Exploration Program, within the Angikuni Basin along the 31 km RIB-Nine Iron Trend (Figure 1);

• RIB East Discovery is currently defined by eight mineralized drill holes, intersecting shallow

uranium mineralization (<275 m depth), the five latest holes extend mineralization from 400 m to a strike length of ~750 m (Figure 2). Based on EM Inversion modelling (see below), RIB East now has prospective strike length of more than 5 km, which remains largely untested by drilling;

• In August 2025, Expert Geophysics Ltd. utilized the MMT survey data acquired in 2024 to

complete Advanced Electromagnetic Inversion modelling (“EM Inversion”) across 12 km of the 31 km long RIB-Nine Iron Trend, focused on the RIB East and West Discovery areas. The EM Inversion has proved successful in mapping out multiple stacked conductors, including numerous interpreted north-south and east-west trending cross cutting structures. Drilling at both RIB East and West has demonstrated the EM Inversion is accurately mapping graphitic structural corridors which are associated with uranium mineralization (Figure 2);

• To date the Company has only explored a small proportion of the 12 km long prospective

EM Inversion model at RIB East and West. The Company will be completing additional EM inversion modelling over the remaining 62% of the RIB-Nine Iron Trend where MMT data was acquired in 2024;

• Through the end of the 2025 Angilak Exploration Program, the Company will be focused on

targeting newly derived EM Inversion anomalies, including the newly identified north-south and east-west cross cutting trends;

• The 2025 Angilak Exploration Program is on-going, to date, only ~55% of expected diamond

drillhole results have been announced.

RIB West Discovery:

• RIB West Discovery is located approximately 1.5 km to the west of the RIB East Discovery

and is currently defined by two drill holes, both intersecting uranium mineralization, over a strike length of approximately ~340 m (Figure 2). The mineralization is hosted within graphitic structures accurately mapped by the advanced EM Inversion. Based on the EM Inversion model, the RIB West Discovery has a prospective strike length over 3 km, with an associated EM conductor;

• RIB_W-DD-001, intersected high-grade uranium mineralization with total composite

mineralization of 2.1 m, hosted within a broad graphitic structure. Mineralization was found between 396.25 m and 398.35 m, including 0.5 m of high-grade mineralization with a maximum down-hole-triple gamma probe value of 18,485 counts per second (CPS¹) over 0.1 m (Figure 2 & 3);

• RIB_W-DD-002, drilled ~340 m along strike to the northeast of RIB_W-DD-001, intersected

six zones of uranium mineralization within a broad graphitic structure. The hole intersected total composite mineralization of 8.5 m between 204.8 m and 269.5 m, including 2.0 m with an average of 1,586 CPS¹ and a max peak of 5,193 CPS¹ (Figure 2 & 4).

RIB East Discovery:

• ATHA has completed eight drill holes at the RIB East Discovery during the 2025 Angilak

Exploration Program (See July 21^st, 2025, News Release, for results from the first three drill holes). To date, all holes have successfully intersected uranium mineralization;

• Today’s release comprises five additional drill holes that have extended the strike length of

mineralization at the RIB East Discovery from 400 m to ~750 m.

• Drilling is highlighted by:
  • RIBE-DD-005, tested 100 m down-dip and 100 m along strike to the north of

mineralization intersected in RIBE-DD-003. The hole intersected three zones of mineralization totaling 2.2 m of composite mineralization, including a shallow interval (between 282.9 m and 284.4 m) of high-grade uranium mineralization that had an average down-hole probe value of 3,711 CPS¹ and a peak of 12,357 CPS¹ over 0.10 m (Figure 2 & 6);

• RIBE-DD-007, was drilled in a scissor orientation ~400 m to the southeast of RIBE-

DD-003. The hole intersected four zones of mineralization (between 192.5 m and 214.9 m) with a total composite mineralization of 6.0 m, including a high-grade intersection from 207.3 m to 209.7 m, with an average down hole probe value of 4,477 CPS¹ and a peak of 19,956 CPS¹, over 0.10 m (Figure 2 & 8).

Troy Boisjoli, CEO commented: “The newest discovery along the 31 km long RIB-Nine Iron Trend – at RIB West – is the Company’s third discovery of the 2025 Angilak Exploration Program. This is an unprecedented feat from a greenfield exploration program targeting uranium discovery and speaks to the metal endowment at the Angilak Project area, beyond the Lac 50 Deposit area and ATHA’s top tier technical teams’ ability to plan and execute on its thesis. We continue to see the hallmarks of a generational bull market for uranium and based on ATHA’s continued exploration success over the last two years, the Company is well positioned to accelerate uranium discovery and build value for this cycle.”

Cliff Revering, VP Exploration added: “We are very excited about the results emerging from the RIB regional target area, including another discovery along the RIB West trend and the continued expansion of the mineralized strike length along the RIB East trend. To date, we have drill-tested only a relatively small proportion of the prospective trends within the RIB area, with all completed holes intersecting uranium mineralization associated with graphitic structural corridors. All prospective trends remain open along strike and at depth. We are also very encouraged by the accuracy of the EM inversion model provided by Expert Geophysics in locating graphitic structural corridors associated with uranium mineralization. This model has been highly valuable in guiding our targeting strategy in the RIB area, and in highlighting numerous additional prospective trends that have yet to be drill- tested.”

Vancouver, British Columbia, September 18^th, 2025 – ATHA Energy Corp. (TSX.V: SASK) (FRA: X5U) (OTCQB: SASKF) (“ATHA” or the “Company”), is pleased to announce that the Company has closed its previously announced underwritten private placement of special warrants (the “Offering”) for aggregate gross proceeds of $11,499,928.30, which included the full exercise of the Underwriters’ option. The Offering was led by Stifel Canada, as lead underwriter and sole bookrunner, on behalf of a syndicate which included Red Cloud Securities Inc. and Paradigm Capital Inc. (collectively, the “Underwriters”). Further details of the Offering are described below. Additionally, the Company is pleased to announce further drilling and geophysics results from the 2025 Angilak Exploration Program at its 100%-owned Angilak Uranium Project in Nunavut, Canada.

The Company has completed two maiden drill holes at the RIB West Discovery resulting in the third new discovery of its 2025 drill program. RIB_W-DD-001 targeted a gravity and EM anomaly located ~1.5 km to the west of the RIB East Discovery. The hole intersected 2.1 m of composite mineralization, including 0.5 m of high-grade uranium mineralization with a peak response of 18,485 CPS¹. The second hole at RIB West, RIB_W-DD-002, drilled approximately 340 m along strike to the north-east of RIB_W- DD-001, successfully intersected 8.5 m of composite mineralization over a broad interval, between 204.8 m and 269.5 m, hosted with a broad graphitic structure. Drilling at RIB West has demonstrated uranium mineralization potential continuity over a 340 m strike length; the majority of the prospective RIB West trend remains untested by drilling.

At the RIB East Discovery, the Company has completed an additional five drill holes. All eight drill holes at the RIB East Discovery have successfully intersected uranium mineralization. With today’s release, the potential strike length of mineralization has been extended from ~400 m to ~750 m. The RIB East Discovery remains open along strike and at depth, with the majority of prospective conductive trend remaining untested.

In mid-August, the Company received results of Advanced Electromagnetic Inversion (“EM Inversion”) modelling work across 12 km of the 31 km long RIB-Nine Iron Trend, focused on the RIB East and West Discovery areas, from Expert Geophysics Ltd. The EM Inversion model utilized MMT survey data that was completed in September of 2024. The EM Inversion has proved successful in mapping out multiple stacked conductors, including numerous north-south and east-west cross cutting trends. Drilling at both RIB East and West has demonstrated the EM Inversion is accurately mapping graphitic structural corridors which are associated with uranium mineralization (Figure 2).

Figure 1: Angilak Project Area – 2025 Exploration Target Area (Black Rectangles) & Mapped Historic

Figure 2: 2025 RIB (East & West) Regional Target Area – EM Inversion Model & Drill Collar Locations at RIB East & West Discoveries Table 1: 2025 Angilak Exploration Program Drill Collar Information

*Previously released drill holes from 2025 Angilak Exploration Program Figure 3: Striplog RIB_W-DD-001 showing radioactivity based on 40TGU-1000 Triple Gamma Down Hole Figure 4: Striplog RIB_W-DD-002 showing radioactivity based on 40TGU-1000 Triple Gamma Down Hole Figure 5: Striplog RIBE-DD-004 showing radioactivity based on 40TGU-1000 Triple Gamma Down Hole Figure 6: Striplog RIBE-DD-005 showing radioactivity based on 40TGU-1000 Triple Gamma Down Hole Figure 7: Striplog RIBE-DD-006 showing radioactivity based on 40TGU-1000 Triple Gamma Down Hole Figure 8: Striplog RIBE-DD-007 showing radioactivity based on 40TGU-1000 Triple Gamma Down Hole Figure 9: Striplog RIBE-DD-008 showing radioactivity based on 40TGU-1000 Triple Gamma Down Hole

Underwritten Private Placement

The Company is also pleased to announce that further to its news release dated September 4, 2025, it has closed its previously announced underwritten private placement of 17,126,138 special warrants