Northisle Identifies High-Grade Trend at Depth in Red Dog Deposit's Eastern Zone

• Drilling in the eastern portion of Red Dog identified a new high-grade mineralized trend extending below the current resource model, including 216.0 metres grading 0.67% copper equivalent, with a higher-grade section of 64.1 metres at 1.10% copper equivalent
• Infill drilling in the western, shallower part of the deposit confirmed consistency with historic drill results
• Drilling in the central portion of the deposit confirmed mineralization consistent with the existing resource model, supporting improved confidence in future estimates
• A total of 8,112 metres were drilled across 31 holes between 2025 and early 2026, with approximately 5,259 metres directed at upgrading portions of the resource from the Inferred to the Indicated category
• A new phase of exploration drilling began on May 29, 2026, with approximately 14,500 additional metres planned for the remainder of the year

Northisle Copper and Gold Inc. (TSX-V: NCX, OTCQX: NTCPF) is a Vancouver, Canada-based company advancing the North Island Project through its wholly owned subsidiary, North Island Mining Corp. The project is a copper and gold porphyry project located near Port Hardy, British Columbia, on a mineral title package of more than 34,000 hectares spanning a 50-kilometre belt that includes the site of the former Island Copper Mine. Since 2021, Northisle has discovered two deposits at the project and expanded its resource base.

New Eastern Trend Identified Below Current Resource Model

Drilling in the eastern portion of the Red Dog deposit identified a previously unrecognised high-grade trend at depth, extending below the boundaries of the currently modelled resource. Historic drilling at Red Dog was concentrated on shallower zones near surface, and the recent program was the first to more fully test the deposit's depth potential.

Several holes confirmed the trend is broad and continuous. Hole RD26-30 returned 216.0 metres grading 0.67% copper equivalent, including a higher-grade interval of 64.1 metres at 1.10% copper equivalent. Hole RD26-35 intersected 163.4 metres grading 0.86% copper equivalent, while RD26-33 returned 126.0 metres grading 0.89% copper equivalent, including a 30.0 metre section at 1.65% copper equivalent. Copper equivalent grade is a way of expressing the combined value of copper, gold and other metals found in a single rock sample as one comparable copper grade, allowing intervals containing multiple metals to be compared directly.

The consistency of these results across multiple drill holes suggests the presence of an emerging eastern high-grade trend. With mineralization now outlined over approximately 800 metres of strike length and more than 400 metres of vertical extent, the deposit remains open in both directions.

Infill Drilling Supports Resource Model Continuity

A significant portion of the drill program was directed at infill drilling, meaning additional holes drilled between existing ones to fill gaps and improve confidence in the resource estimate. Of the 8,112 metres drilled, approximately 5,259 metres were dedicated to upgrading portions of the resource from the Inferred to the Indicated category.

Results from the shallower western core, where historic drilling density is already high, confirmed continuity with previous data. Hole RD26-29 returned 141.4 metres grading 0.97% copper equivalent, including 76.0 metres at 1.02% copper equivalent, while RD26-32 intersected 142.5 metres grading 0.67% copper equivalent. In areas where wider historic drill spacing had limited confidence, additional holes also confirmed broad, continuous mineralization.

Pablo Mejia, Vice President, Exploration, said:

"These results from Red Dog represent some of the most significant geological outcomes of Northisle's ongoing exploration program, with drilling confirming the potential for additional mineralization below the current resource envelope and that higher-grade mineralization is not restricted to the shallow core of the deposit. Critically, the use of Scan technology (by Veracio), combined with our improved understanding of the North Island Project mineralized systems, contributed to this important outcome."

Scan technology provides near real-time chemical readings of drill core, allowing geologists to make faster decisions while drilling is underway.

Results Being Integrated into Ongoing Pre-Feasibility Study

Following the drill program, Northisle is incorporating the Red Dog results into its integrated resource estimate for the North Island Project, and subsequently into the pre-feasibility study (PFS) currently underway. A PFS is a mid-stage technical and economic study used to assess whether a mining project is likely to be commercially viable before more detailed engineering work is undertaken.

Incorporating the new data means the updated resource model will reflect both the infill drilling results and the eastern high-grade trend, ahead of the integrated resource update planned for the second or third quarter of 2026.

Sam Lee, President and CEO, said:

"Exploration at Red Dog has demonstrated very strong grades over wide intervals, both near surface and at depth, and has identified a new mineralized domain in a previously under-drilled area. We are only scratching the surface of the potential of this district-scale opportunity and will be initiating further drill programs imminently. These important results have the potential to contribute to an improved project and, as a result, we have taken the necessary steps to allow inclusion of the new Red Dog mineralization in the PFS."

Milestones and Next Steps

Completed 2026 milestones include an updated Preliminary Economic Assessment for the North Island Project, financings totalling C$39.5 million and C$115 million, and the largest field program in the company's history, at 20,297 metres across 58 holes. Looking ahead, Northisle expects to release initial metallurgical test results and an integrated resource update for the North Island Project in the second or third quarter of 2026. Drilling at regional exploration targets is planned to begin in the third quarter, with results expected in the fourth quarter. The PFS is targeted for completion in the fourth quarter of 2026 or the first quarter of 2027, alongside continued engagement with First Nations and local stakeholders.