Mr. Philip Williams reports

ISOENERGY COMMENCES 8,000 METRE SUMMER DRILL PROGRAM AT THE LAROCQUE EAST PROJECT, ATHABASCA BASIN

IsoEnergy Ltd. has commenced its 2026 summer exploration program on the Larocque East project, which hosts the high-grade Hurricane deposit, in the eastern Athabasca basin, Canada. The program is planned to comprise approximately 8,000 metres of diamond drilling across up to 20 drill holes, focused on following up high-grade winter 2026 results (see press release dated May 12, 2026) along the highly prospective Hurricane South trend.

Hurricane hosts a current mineral resource of 48.6 Mlb (million pounds) U3O8 (triuranium octoxide) at 34.5 per cent U3O8 indicated, and 2.7 Mlb U3O8 at 2.2 per cent U3O8 inferred. The project benefits from excellent infrastructure, located approximately 40 km northwest of the McClean Lake mill and features relatively shallow mineralization at approximately 325 m depth, supporting efficient exploration and future development optionality. The deposit is located on the Larocque trend, an important regional structure that also hosts other notable high-grade occurrences including those on Cameco and Orano's Dawn Lake joint venture.

Highlights

• Summer drilling has commenced: Approximately 8,000 m of diamond drilling is planned across up to 20 holes targeting the Hurricane South trend and is under way.
• Building on high-grade winter results: Winter 2026 drilling returned 4.21 per cent U3O8 over 3.5 metres, including 11.61 per cent U3O8 over 1.0 m, in hole LE26-248 within the newly reinterpreted L Fault zone, with additional intercepts of 2.75 per cent U3O8 over 0.5 m in LE26-234 and 1.75 per cent U3O8 over 0.5 m in LE26-243, approximately 525 m east of the resource envelope, along the South trend (see May 12, 2026, press release for complete results).
• Expansion potential: Summer drilling is designed to test the South trend along strike east of LE26-248 and LE21-107, both of which intersected high grade mineralization along the J-L fault corridor.
• Advancing target pipeline on eastern Athabasca projects: Airborne MobileMT surveys and ground fieldwork to investigate anomalies identified during 2024 RAMP helicopter-borne radiometric surveys, are planned to develop drill targets on four prospective early stage projects, as well as the western portion of Larocque East.

Dan Brisbin, vice-president of exploration, stated: "Following the high-grade results returned from the winter program along the Hurricane South trend, our team has mobilized for an aggressive summer follow-up. The LE26-248 intersection opened an underexplored corridor along the southernmost fault strands of the Hurricane fault zone, and this 8,000 m program is designed to test the scale of that opportunity along strike, and to test additional targets within the broader Hurricane South trend."

South trend

The Hurricane South trend is a compelling exploration trend with mineralization intersected in multiple holes over a 500 m strike length to the east of the Hurricane deposit. Winter 2026 drilling tested the South trend in the low-grade zone of the deposit and along strike to the east, building on previous drilling during which mineralization was intersected near the unconformity in drill holes LE25-207, LE25-210, LE21-101 and LE22-115A (see press release dated Dec. 3, 2025). Recently received assay results confirmed high-grade mineralization within the newly reinterpreted L Fault zone, including 4.21 per cent U3O8 over 3.5 m in LE26-248, demonstrating strong potential to expand mineralization beyond the current resource footprint (see news release dated May 12, 2026). Summer 2026 drilling will follow up along this trend, focusing on stepouts from LE26-248 and the along-strike extension to the east. Potential for high-grade mineralization like the 20.4 per cent U3O8 intersected over 6.5 m in 2021 drill hole LE21-107 (see news release dated Feb. 3, 2022) will also be tested along the J-K fault zone within the broader South trend east of the deposit.

Athabasca projects target development

In addition to Larocque East, IsoEnergy has 14 prospective early stage projects in the eastern Athabasca basin on which a pipeline of drill targets is being developed. Summer work is planned across four of these early stage projects, as well as the western portion of Larocque East. Airborne MobileMT surveys are planned for the Trident, Ranger and western Larocque East projects, complementing MobileMT surveys previously completed on the East Rim and Evergreen projects, expected to provide conductivity and magnetic information that will advance interpretation of structural geology, alteration and basement rock types.

Prospecting and geological fieldwork are planned on the Evergreen and East Rim projects in late summer to investigate radiometric anomalies identified by RAMP high-resolution helicopter-borne radiometric surveys completed in 2024.

Qualified person statement

The scientific and technical information contained in this news release was reviewed and approved by Dr. Dan Brisbin, PGeo, IsoEnergy's vice-president, exploration, who is a qualified person (as defined in National Instrument 43-101 -- Standards of Disclosure for Mineral Projects). See the April 6, 2026, press release for information on quality assurance/quality control procedures, as well as the complete exploration results from the previous programs disclosed herein. Dr. Brisbin has verified the data disclosed herein. Data verification procedures included comparing radioactivity measured on core with the RS-125 spectrometer to radioactivity measured downhole with the 2PGA probe, comparing RS-125 data with cps (counts per second) values marked on core boxes in core photos, and checking reported composite lengths and cps values.

For additional information regarding the company's Larocque East project, including the current mineral resource estimate for IsoEnergy's Hurricane deposit, please see the technical report entitled "Technical Report on the Larocque East Project, Northern Saskatchewan, Canada" dated Aug. 4, 2022, available on the company's profile at SEDAR+.

About IsoEnergy Ltd.

IsoEnergy is a leading, globally diversified uranium company with substantial current and historical mineral resources in top uranium mining jurisdictions of Canada, the United States and Australia at varying stages of development, providing near-, medium- and long-term leverage to rising uranium prices. IsoEnergy is currently advancing its Larocque East project in Canada's Athabasca basin, which is home to the Hurricane deposit, boasting the world's highest-grade indicated uranium mineral resource.

IsoEnergy also holds a portfolio of permitted past-producing, conventional uranium and vanadium mines in Utah with a toll milling arrangement in place with Energy Fuels. These mines are currently on standby, ready for rapid restart as market conditions permit, positioning IsoEnergy as a near-term uranium producer.

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