Midnight Sun’s Dumbwa Copper Deposit More Than Doubles in Width to Over 2.4 km in Northern Block

Recent Drill Results Show Growth Along 12 Kilometres of Strike Highlighted by 31 m @ 0.47% Cu, 11 m @ 0.67% Cu, 7 m @ 1.05% Cu, and 14 m @ 0.48% Cu – 70 Holes Pending and Drilling Ongoing

VANCOUVER, British Columbia, Oct. 27, 2026 (GLOBE NEWSWIRE) — Midnight Sun Mining Corp. (TSXV: MMA / OTCQX: MDNGF) (“Midnight Sun” or the “Company”) is pleased to report ongoing drilling at its Dumbwa copper deposit in Zambia has identified a significant expansion of the mineralized system in the Northern Block. Recent drilling has encountered near-surface copper mineralization across an east-west extent exceeding 2,400 metres, which is more than double the average width of the previously drilled Dumbwa Mineralized Corridor. This expanded footprint represents a major development as the Company advances its Phase Two exploration program, with drilling continuing to test the northern extent of Dumbwa and further define the distribution of copper mineralization within the broader system.

With the copper mineralization continuing to be flat-laying to shallowly dipping, and located at or very near surface, this is another promising development at Dumbwa.

“As drilling progresses north, we appear to have passed through another structural disruption and are now encountering copper sulphide mineralization across significantly greater east-west widths, with locally increased mineralized thicknesses. These observations are providing exciting insight into the geological architecture of the Northern Block and will help guide our ongoing exploration of this expanding system” states Midnight Sun’s COO, Dr. Kevin Bonel.

Figure 1. Assay Results and Interpreted Dumbwa Mineralized Corridor

Drill Results
The Company has, after lengthy delays due to ongoing issues at contracted analytical facilities (see below), received results from 76 drill holes representing 17,373 metres of drilling. The results include assays from both the expansion and the delineation drill programs which are ongoing at Dumbwa.

Recent assay results continue to deliver multiple shallow, higher grade, copper intercepts within broader zones of copper sulphide mineralization. The results reported today are from holes drilled across various areas of the strike length of the deposit and include holes which had previously failed to meet the Company’s QA/QC standards and were therefore not previously reported. Highlights include:

• DBW-26-283 – 0.47% Cu over 31.1 m,

  including – 0.81% Cu over 16.0 m.

• DBW-26-261 – 0.67% Cu over 11.0 m.
• DBW-26-355 – 1.05% Cu over 7.0 m.
• DBW-26-266 – 0.48% Cu over 14.0 m.

Midnight Sun’s President and CEO, Al Fabbro, states, “Phase One was designed to rapidly and systematically establish scale and outline the geological architecture of Dumbwa. I am extremely proud of what our team has accomplished, demonstrating more than 12 kilometres of mineralized strike length in just 14 months.

Importantly, our ongoing drilling is now identifying a significant expansion of the mineralized system in the north, along with distinct zones of enhanced copper mineralization throughout the main corridor. The geological insights gained through Phase One are now allowing us to focus Phase Two drilling on the most prospective areas of the Dumbwa system.”

Drilling Highlights:

• Assay results based on four-acid digest, ICP-OES finish.
• Drill indicated thicknesses are estimated to represent 85% to 100% of true width.
• The full table of assays including locations is available on the Company’s website and can be accessed through this link: Dumbwa Drill Hole Location and Assay Table.

Phase One Program Recap

The field component of the Company’s Phase 1 drill program is now complete, although some assays are still pending. The program, which consisted of 372 diamond drill holes totalling over 87,000 metres (see Company’s news releases for previously announced 214 drill holes totalling 44,941 metres), has demonstrated copper sulphide mineralization along more than 12 km of the Dumbwa Mineralized Corridor, comprising the southern portion of the broader 20 km Dumbwa Target as outlined by geophysics and soil sampling.

The Phase 1 drill program had two primary goals. The first goal was to discover the source of a laterally extensive, open ended, copper-in-soil anomaly which was previously outlined at Dumbwa, and located directly south of First Quantum Minerals’ Kansanshi Mine.

On this front, the program has been an unqualified success. With the discovery and emerging understanding of the Dumbwa copper deposit providing the Company and its shareholders with a unique asset, in a globally significant copper belt, at a time when the copper price is at or near its all-time highs.

The second goal was to quickly and efficiently define the full extent of Dumbwa. On that front, the program has also been highly successful, as demonstrated by the outlining of the copper system along strike for over 12 km and recently identifying a doubling in the width of the system as exploration continues to track Dumbwa northwards. However, this goal remains unfinished, for positive reasons, as the Dumbwa deposit remains open for further expansion to both the north and south.

Assay Reporting Update

The Company has continued to experience extended assay turnaround times due to increased regional sample volumes, power interruptions and equipment failures at Intertek’s Kitwe preparation facility in Zambia.

Intertek has implemented measures to address these delays, including transferring samples to its Johannesburg facility for preparation, and prioritizing the Company’s outstanding samples for analysis in Perth, Australia.

Of the outstanding samples, 1,824 have now been received in Perth for priority analysis, with results targeted by October 30, subject to analytical completion and QA/QC requirements. A further 1,000 samples have been transferred to Johannesburg for preparation, while 859 samples remain in processing at Kitwe, with both batches expected to progress to Perth in the coming days.

Intertek has also committed to equipment upgrades at its Kitwe facility, including replacement pulverising mills and an additional crusher, with commissioning targeted for December 1, 2026. These improvements are expected to increase processing capacity and improve turnaround times going forward.

Approximately 5,000 samples, representing 70 drill holes remain outstanding (see Figure 1).

Midnight Sun continues to utilize multiple laboratories and maintain its strict internal QA/QC procedures to ensure the reliability of reported results. The Company recognizes the importance of timely and consistent technical updates and is implementing measures to both improve assay turnaround time, and provide more consistent and frequent reporting as pending assay results are received and validated.

Ongoing Phase 2 Program

At this time, drilling is focused on the Northern Block of the Dumbwa Mineralized Corridor, where the Company continues to be greatly encouraged by both the overall width of the mineralized zone and the local intensity of the mineralization observed during the logging of drill core from recent drill holes.

In addition, soil sampling continues in both the north and south of Dumbwa as the Company looks to generate additional targets that may sit outside of the established mineralized corridor.

Quality Control/Quality Assurance

Drilling was conducted using a conventional diamond drilling rig and drill core was captured for the entirety of each hole and placed into plastic core trays. All drill holes were cored in PQ until stable ground was achieved and then reduced to HQ size for the remainder of each hole. Sampling was based on visible copper mineralisation, and sample intervals honoured any important lithological boundaries. Core was then cut in house using a diamond saw and the right half of core was placed into a 200-micron plastic bag, assigned a unique sample number, and recorded into the GeoSpark Core database system.

To maintain chain of custody, samples always remained under the supervision of Midnight Sun staff prior to delivery to an independent assay lab. Drill samples were delivered to, prepared and analysed by either SGS Labs in Kitwe, Zambia or to Intertek where sample preparation took place in their Kitwe facility prior to an analysis of pulps in their facility located in Perth, Western Australia. Both laboratories conducted analysis by four-acid digest with ICP-OES finish.

Midnight Sun follows an in-house QA/QC program that consists of a random insertion every 10^th sample of either a coarse blank, fine blank, coarse duplicate, fine duplicate, or Certified Reference Material (standards). The Company has encountered multiple and repeated reporting failures provided by the independent laboratories and only reports results which have met its stringent internal QA/QC standards. Where samples fail QA/QC, the Company requests re-analysis of samples until the appropriate QA/QC checks are met.

Qualified Person: Darin Labrenz, P.Geo., a consulting geologist for the Company and Qualified Person under NI 43-101, has reviewed and approved the technical data and contents of this release.

About Midnight Sun

Midnight Sun is rapidly advancing the Solwezi Copper Project, with a focus on our flagship Dumbwa copper deposit. The Project is located near the town of Solwezi in the heart of the Zambia–Congo Copperbelt, the world’s second-largest copper-producing region. This prolific mining district is renowned for hosting multiple major copper deposits, and benefits from excellent infrastructure, an established mining workforce, and a long history of successful production.

The Solwezi Copper Project is surrounded by producing copper mines, including the geologically similar Lumwana mine to the west and First Quantum’s Kansanshi mine – Africa’s largest integrated metallurgical processing facility, approximately 6 kilometres east of the Company’s recently announced Kazhiba Oxide Resource. This highly favourable location highlights the district-scale potential of Midnight Sun’s land package.

The Dumbwa copper deposit underlays a robust 20-kilometre copper-in-soil anomaly, and ongoing drilling has demonstrated strong geological similarities to the nearby Lumwana mine, underscoring the potential scale of this newly identified copper system.

Led by an experienced geological team with a proven track record of major discoveries in the Zambia–Congo Copperbelt and globally, Midnight Sun’s goal is to delineate Zambia’s next generational copper deposit.

ON BEHALF OF THE BOARD OF MIDNIGHT SUN MINING CORP.
Al Fabbro
President & CEO

For Further Information Contact:
Adrian O’Brien
VP Business Development and Communications
Tel: +1 604 809 6890
Em: adrian@midnightsunmining.com

NEITHER THE TSX VENTURE EXCHANGE NOR ITS REGULATION SERVICES PROVIDER (AS THAT TERM IS DEFINED IN THE POLICIES OF THE TSX VENTURE EXCHANGE) ACCEPTS RESPONSIBILITY FOR THE ADEQUACY OR ACCURACY OF THIS NEWS RELEASE.

This news release contains “forward-looking statements” within the meaning of the applicable Canadian securities legislation that are based on expectations, estimates, assumptions, geological theories, and projections as at the date of this news release. The information in this news release about any information herein that is not a historical fact may be “forward looking statements.” Any statement that involves discussions with respect to predictions, expectations, beliefs, interpretations, plans, projections, objectives, assumptions, future events or performance (which may, but not always, include phrases such as “anticipates”, “expects”, “plans”, “scheduled”, “believed” or “intends” or variations of such words and phrases or stating that certain actions, events or results “may” or “could”, “would”, “might” or “will” be taken to occur or be achieved) are not statements of historical fact and may be forward-looking statements and are intended to identify forward-looking statements. Forward looking statements made in this news release include statements regarding (i) timing of assays on approximately 1,800 outstanding samples, (ii) measures being taken to improve assay turn around time, (iii) anticipated improvements in assay turn around time based on measures taken and being taken, (iv) anticipated assay results based on visual inspections, and (iv) the continuation of mineralization along strike to the north and south.

Although the forward-looking statements contained in this news release are based upon what management believes, or believed at the time, to be reasonable assumptions, the Company cannot assure readers that actual results will be consistent with such forward-looking statements, as there may be other factors that cause results not to be as anticipated, estimated or intended. Such factors include, among others, risks relating to the timing and ability of the Company to obtain and the timing of the approval of relevant regulatory bodies, if at all; risks relating to property interests; risks related to access to the project; risks inherent in mineral exploration, including the fact that any particular phase of exploration may be unsuccessful; the availability of contractors; geo-political risks; the global economic climate; metal prices; environmental risks; political risks; and community and non-governmental actions. Further to this, the Company is dependent on third party service providers for the delivery of assay services, over which the Company has limited or no control. Assay laboratories servicing Zambian exploration and mining companies are extremely busy and may prioritize other companies over the Company, may experience power and other technical failures, and may not have capacity to service the Company on the basis the Company expects. With respect to the exploration potential at Dumbwa, there is no guarantee that mineralization will continue along strike either to the north or south, which can only be determined through additional drilling, which may not be successful. Neither the Company nor any other person assumes responsibility for the accuracy and completeness of any such forward-looking statements. The Company does not undertake, and assumes no obligation, to update or revise any such forward-looking statements or forward-looking information contained herein to reflect new events or circumstances, except as may be required by law.

A photo accompanying this announcement is available at https://www.globenewswire.com/NewsRoom/AttachmentNg/19dac661-079f-4940-a8d8-8ca0e0ef1206