Mr. Ian Klassen reports

GRANDE PORTAGE RESOURCES REPORTS POSITIVE RESULTS FROM PRELIMINARY STRENGTH TESTING OF MINE BACKFILL MATERIALS

Grande Portage Resources Ltd. has provided a project update for the New Amalga gold property near Juneau, Alaska.

The company has received laboratory results for preliminary backfill strength testing of CRF (cemented rockfill) samples, which were cast using material sourced from core samples drilled during previous field seasons. The waste-rock lithologies in these samples were selected to be aligned with those that will be encountered during mine development as well as those which would be present in ore-sorter reject material.

These samples were cast into test cylinders using a 4-per-cent cement binder content and were tested for uniaxial compressive strength (UCS) after 10-day and 17-day cure times.

All samples met or exceeded the preliminary strength criteria selected for overhand long-hole stoping, the primary mining method planned for New Amalga. Based on these results, the company intends to advance both the waste rock from mine development as well as the ore-sorter reject rock as feedstocks for making CRF backfill.

Future test work with greater cement proportions will be undertaken to evaluate backfill for underhand stoping, a secondary mining method that is planned to be utilized for a small proportion of New Amalga production and which requires higher-strength backfill.

Ian Klassen, president and chief executive officer, commented: "This is an important derisking milestone. We are very pleased with results of this initial test work, demonstrating that development waste rock and ore-sorter reject rock are appropriate feedstocks to advance for structural backfill use at New Amalga. This further validates our small-footprint strategy, which results in all waste and reject rock being placed back underground, avoiding the need for permanent disposal facilities on surface. This approach can be expected to not only reduce surface disturbance but also lower future reclamation obligations and simplify environmental permitting."

Additionally, geochemical test work is currently in progress on New Amalga core samples representing all major rock types present at the deposit to determine whether any have the potential to be reactive (acid generating or metals leaching) over the long term. Previous limited test work conducted in 2020 to 2021 on a small number of New Amalga wallrock samples showed favourable preliminary results, demonstrating significant net-acid-neutralizing potential ratios. For more details, see the company's April 28, 2026, news release titled "Grande Portage Resources Initiates Full Scale Geochemical Characterization Program and Backfill Testwork for the New Amalga Gold Project."

Project summary

The New Amalga gold project is located only 25 kilometres from Alaska's capital city of Juneau and six kilometres from paved highway. The resource remains open to expansion in multiple directions and hosts an indicated resource of 1,438,500 ounces of gold at an average grade of 9.47 grams per tonne gold (4,726,000 tonnes) and an inferred resource of 515,700 ounces of gold at an average grade of 8.85 g/t Au (1,813,000 tonnes) (with an effective date of July 17, 2024).

The current development concept envisions a small-footprint underground mining operation which would transport material off site for processing by a third party, eliminating the need for an on-site gold recovery plant or tailings storage facility.

This set-up is designed to provide several benefits:

• Eliminates the need to build a gold recovery plant, minimizing mine footprint, power requirements and reducing project construction capex (capital expenditures);
• Eliminates the need to develop a tailings disposal facility at the site as no tailings would be generated;
• Removes the need for permanent waste rock storage facilities; waste rock generated from mine development would be returned to the underground workings as stope backfill;
• No use of chemical reagents for gold processing at the site;
• Dramatically reduces land usage and overall environmental footprint;
• Greatly facilitates postmining closure and reclamation;
• Simplifies the environmental review and permitting process.

Project highlights:

• A 100-per-cent interest in the New Amalga gold project, located near infrastructure only 25 kilometres north of Juneau, Alaska, and six kilometres from paved all-season highway;
• Excellent economics demonstrated by National Instrument 43-101 preliminary economic assessment (with an effective date of Feb. 11, 2026):
  • At base-case gold price of $3,200 (U.S.) per ounce: after-tax net present value (discounted at 5 per cent) of $721-million and after-tax internal rate of return of 56 per cent;
  • At upside-case gold price of $5,000 (U.S.) per ounce: after-tax net present value (discounted at 5 per cent) of $1,557-million (U.S.) and after-tax internal rate of return of 91 per cent;
• The property is host to at least eight large, long, gold-bearing mesothermal veins;
• 240 drill holes from 55 platforms totalling approximately 65,000 metres confirm a large gold-quartz system;
• Past drilling produced multiounce assays on several veins; select samples include:
  • Deep Trench vein: 15.3 m grading 37.1 g/t Au, 8.3 m grading 58.6 g/t Au and 11.6 m grading 28.3 g/t Au;
  • Goat vein: 2.1 m grading 74.2 g/t Au and 6.3 m grading 15.7 g/t Au;
  • Main vein: 3.1 m grading 79.2 g/t Au, 2.1 m grading 37.2 g/t Au and 3.1 m grading 13.9 g/t Au;
  • Ridge vein: 1.5 m grading 43.0 g/t Au and 1.5 m grading 29.2 g/t Au;
  • Sleeping Giant vein: 2.1 m grading 15.4 g/t Au and 3.2 m grading 20.7 g/t Au;
• The company's updated NI 43-101 mineral resource estimate (MRE) with an effective date of July 17, 2024, reported an indicated resource of 1,438,500 ounces of gold at an average grade of 9.47 g/t Au (4,726,000 tonnes) and an inferred resource of 515,700 ounces of gold at an average grade of 8.85 g/t Au (1,813,000 tonnes) as well as an indicated resource of 891,600 ounces of silver at an average grade of 5.86 g/t Ag (4,726,000 tonnes) and an inferred resource of 390,600 ounces of silver at an average grade of 7.33 g/t Ag (1,813,000 tonnes);
• The deposit is open to the north, south and at depth;
• Goat vein surface outcrop channel samples assayed 129.02 g/t Au (3.76 ounces per ton) and 290 g/t Au (8.46 ounces per ton) with 224 g/t Ag (6.53 ounces per ton);
• Lidar survey of property discovered numerous targets -- the first of these tested confirmed gold discovery;
• Received excellent metallurgical recoveries up to 98.2 per cent;
• Completed more than six years of environmental baseline water sampling;
• Current development strategy envisions a small-footprint underground mining operation with third party off-site processing, eliminating the need for an on-site mill or tailings storage facility; this configuration reduces capital costs, greatly minimizes the project's environmental footprint and facilitates permitting;
• LOI (letter of intent) signed with Goldbelt Inc. (an Alaska native corporation organized under the Alaska Native Claims Settlement Act) for development of an ore export terminal at Cascade Point, Goldbelt's privately held parcel located only 22 kilometres from the project site.

Kyle Mehalek, PE, is the qualified person within the meaning of NI 43-101 and has reviewed and approved the technical disclosure in this release. Mr. Mehalek is independent of Grande Portage within the meaning of NI 43-101.

About Grande Portage Resources Ltd.

Grande Portage Resources is a publicly traded mineral exploration company focused on advancing the New Amalga mine project, the outgrowth of the Herbert gold discovery situated approximately 25 kilometres north of Juneau, Alaska. The company holds a 100-per-cent interest in the New Amalga property. The New Amalga gold system is open to length and depth and is host to at least six main composite vein-fault structures that contain ribbon structure quartz-sulphide veins. The project lies prominently within the 160-kilometre-long Juneau gold belt, which has produced over eight million ounces of gold.

The company's updated NI 43-101 mineral resource estimate (MRE), reported at a base-case mineral resources cut-off grade of 2.5 g/t Au, consists of an indicated resource of 1,438,500 ounces of gold at an average grade of 9.47 g/t Au (4,726,000 tonnes) and an inferred resource of 515,700 ounces of gold at an average grade of 8.85 g/t Au (1,813,000 tonnes) as well as an indicated resource of 891,600 ounces of silver at an average grade of 5.86 g/t Ag (4,726,000 tonnes) and an inferred resource of 390,600 ounces of silver at an average grade of 7.33 g/t Ag (1,813,000 tonnes). The MRE was prepared by Dr. David R. Webb, PhD, PGeol, PEng (DRW Geological Consultants Ltd.), with an effective date of July 17, 2024. Additional information on the New Amalga mine project is available in the technical report titled "Technical Report of the Herbert Gold Property, Juneau District, Southeast Alaska," dated July 17, 2024, which is available under Grande Portage's SEDAR+ profile.

We seek Safe Harbor.