NexGen Expands High-Grade Subdomain Vertical Extent by 17% to 644 m and Intersects Continuous Strong Mineralization Across Patterson Corridor East (PCE) while Adding Fifth Drill to Advance Optimally

Highlights:

• Vertical extent of high-grade subdomain increased by 94 m to 644 m with RK-26-293 intersecting cumulative 4.7 m of >10,000 cps, including 0.1 m of >61,000 cps at 930 m depth.

• Down plunge test hole, RK-26-290c1, intersected multiple stacked uranium veins across 40 m of the high-grade subdomain intersecting cumulative 19.5 m of >10,000 cps including 12.9 m of >10,000 cps that surrounds 5.2 m of >61,000 cps.

• Internal continuity strong throughout highlighted by RK-26-294 intersecting cumulative 6.9 m of >10,000 cps including 3.1 m of >61,000 cps located 27 m up dip of RK-24-222 (17.0 m at 3.85% U3O8).

• Holes RK-26-290c1 and RK-26-294 represent the two best holes for 2026 to date, and rank as the best and third best holes, based on cumulative >61,000 cps, intersected at PCE since discovery.

• Additionally, the up dip high-grade subdomain expanded by 50 m in RK-26-296 that returned cumulative 3.5 m of >10,000 cps including 0.4 m of >61,000 cps.

• NexGen adding a fifth drill rig to continue to advance PCE optimally.

Vancouver, British Columbia--(Newsfile Corp. - August 25, 2026) - NexGen Energy Ltd. (TSX: NXE) (NYSE: NXE) (ASX: NXG) ("NexGen" or the "Company") announces results from the early portion of 2026 summer drilling at PCE which expanded the high-grade subdomain both up and down dip while continuing to demonstrate strong internal continuity of intense high-grade mineralization (Figures 1 and 2, Table 1).

High-grade uranium mineralization now extends to 930 m with hole RK-26-293 intersecting cumulative 4.7 m of >10,000 cps including 0.1 m of >61,000 cps. This hole expanded the vertical extent by 94 m, a 17% increase to 644 m. This zone of intense mineralization is accompanied by strong, broad hydrothermal alteration with notable potential for additional mineralized continuation nearby and below (Figures 1 and 2). The strike extent remains at 210 m as recent tests primarily focused on confirmation of deep-seated interpretations.

RK-26-290c1 designed as a down-plunge test in hole delivered a dual purpose as a test across the full extent of the previous known mineralized footprint of PCE in order to understand the geometry, continuity and extents of high-grade zones within the overall mineralization. This hole intersected multiple stacked uranium veins across 40 m of the high-grade subdomain with cumulative 19.5 m of >10,000 cps including 12.9 m of >10,000 cps that surrounds 5.2 m of >61,000 cps. This is the best hole to date at PCE based on >61,000 cps. Advancement of the model was optimized with confirmation of interpretations as well as critical identification of repeating, mineralization-controlling structural disruptions.

RK-26-294 delivered confirmation of strong internal continuity of intense mineralization intersecting cumulative 6.9 m of >10,000 cps including 3.1 m of >61,000 cps located 27 m along strike of RK-24-222 (17.0 m at 3.85% U3O8) (Figures 1 to 4). Together with RK-26-290c1, these holes combined represent the two best holes drilled to date in 2026.

Additional new drilling shown in Figures 1 and 2, and Table 1, tested the mineralized extents and key areas within the high-grade subdomain. These holes provided crucial geological orientation information that influences extents of the model, in particular the high-grade component. An example being RK-26-296 with cumulative 3.5 m of >10,000 cps including 0.4 m of >61,000 cps that expanded the shallowest portion of PCE by 50 m along strike. Overall, the bulk of high-grade subdomain mineralization at PCE is 70 m shallower than the A2 High-Grade (HG) Zone.

Jason Craven, Vice President of Exploration, commented: "Growth of the high-grade subdomain continues to exceed expectations with expansions across the areas of focus with mineralization still open in most directions. Establishing clear connectivity between intense high-grade intersections with RK-26-290c1 and RK-26-294, which both hit broad zones of intense uranium mineralization is a material advancement of this discovery. In addition, RK-26-293 is extremely exciting as it has expanded the high-grade subdomain by 94 m and opened this area up for potential high-impact growth of this high-grade mineralization."

Leigh Curyer, Chief Executive Officer, commented: "Given today's results at PCE, the team is adding a fifth drill rig for the remainder of the 2026 program. In parallel, with construction of the Rook I Project, the team is delivering on multiple fronts and simultaneously expanding the long-term growth profile of NexGen as a world leader in the provision of this key energy fuel."

Drilling at PCE recommenced on May 28, 2026 and to date in 2026 a total of 20,138.7 m has been completed of the planned 42,000 m, focusing on high-grade growth and expansion of mineralization. Eleven drillholes this summer totalling 7,425.2 m have further tested the mineralization at PCE. NexGen has added a fifth drill rig to continue to advance this uranium discovery optimally. Additional tests of the parallel trend at PCE are planned as part of the remainder of summer drilling. Samples from 2026 drilling are continuously submitted to the independent Saskatchewan Research Council Geoanalytical Laboratory (SRC), with results to follow.

Figure 1: Interpreted 3D model of PCE shown looking northwest (across strike) and northeast (along strike); RK-26-290c1, RK-26-293, and RK-26-294 intersections outlined in purple; mineralization remains open, particularly below entire high-grade subdomain

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Figure 2: Interpreted model of mineralization at PCE (as of this release); new holes emphasized by larger diameter pierce points and bold labels with the trace of down plunge test in dashed black; view is a long section that looks perpendicular to the primary mineralized plane; total mineralized footprint in orange and the high-grade subdomains in red

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Figure 3: Core photo from RK-26-294 displays cumulative 3.1 m of off-scale (>61,000 cps) uranium mineralization between 656.9 and 665.4 m down hole; yellow outlines >1,000 cps, red outlines >10,000 cps, >61,000 cps outlined in purple

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Figure 4: Core photo from RK-26-290c1 displays cumulative 5.2 m of off-scale (>61,000 cps) uranium mineralization between 451.4 and 491.4 m down hole; yellow outlines >1,000 cps, red outlines >10,000 cps, >61,000 cps outlined in purple

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Table 1: Spectrometer results since April 22, 2026 release