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Midnight Sun Mining Corp. Earnings Release 2026

May 13, 2026

46158_rns_2026-05-13_32837d6b-279c-45e7-8f31-25969795c4ff.pdf

Earnings Release

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Midnight Sun Extends Dumbwa Copper Deposit to Over 5.3 Kilometres; Remains Open Along Strike With Drilling Ongoing

Results include: 93m @ 0.40% Cu, 80m @ 0.39% Cu, 44m @ 0.53% Cu, and 36m @ 0.58% Cu

Vancouver, British Columbia, May 13, 2026 – Midnight Sun Mining Corp. (TSXV: MMA / OTCQX: MDNGF) (“Midnight Sun” or the “Company”) is pleased to report results from drillholes completed on its wholly owned Dumbwa copper deposit, located in Solwezi, Zambia. Dumbwa is in the southeast portion of the Company’s Solwezi Project, centered in the heart of the prolific Domes Region - flanked to the north by First Quantum’s Kansanshi mine and west by Barrick’s Lumwana mine.

Drilling has now surpassed 200 holes for a total of over 42,000 metres (“m”) and results to date confirm near surface copper sulphide mineralisation, over a continuous strike length of 5.3 kilometres (“km”) ( see Figures 2 and 3 ), with assays received for the first ~4km of drilled strike. The initial discovery and delineation drill program continues with 4 rigs focussed on growing the deposit to the north along strike and to extend previously drilled mineralisation east and west. Quality control issues related to laboratory analysis have been resolved, and the related backlog of assays are now largely caught up ( see below ).

The Company plans to host a technical webinar with Midnight Sun’s COO, Dr. Kevin Bonel, to discuss the results announced in this news release. Details will be included in a separate news release.

Top 20 Drill Highlights:

Hole ID From(m) To(m) Interval(m) Cu(%)
DBW-25-099R 58 60 2 0.54
152 245 93 0.40
29 33.78 4.78 0.31
DBW-25-123 59 67 8 0.44
127 207 80 0.39
DBW-25-036 0 44 44 0.53
and 119.54 137 17.46 0.37
52 57 5 1.75
DBW-25-111 63 79 16 0.35
132 221 89 0.25
11 20.6 9.6 0.18
77 91 14 0.19
DBW-25-122 106 142 36 0.58
including 127 142 15 1.03
171 238 67 0.30
0 17 17 0.20
41 102 61 0.34
including 41 47 6 1.30
DBW-25-147 82 85 3 1.38
111 126 15 0.27
154 168.05 14.05 0.51
182 183 1 1.34
DBW-25-064 0.7 47 46.3 0.42
DBW-25-114 26 32 6 0.21
43 87 44 0.37
122 208.5 86.5 0.15
23 40.84 17.84 0.85
DBW25149 Including 31 39 8 1.71
-- 50.58 72 21.42 0.38
171 197.65 26.65 0.38
42 77 35 0.36
DBW-25-110 89 102 13 0.34
145 154 9 0.20
DBW-25-065 91 98 7 0.16
127 163 36 0.33
38 43 5 0.19
DBW-25-106 59 67 8 0.4
173 210 37 0.31
27 36 9 0.34
DBW-25-031 119 142 23 0.49
160 181 21 0.34
DBW-25-037 0 42 42 0.25
42 72 30 0.32
DBW-25-127 96 107 11 0.53
174.95 180 5.05 0.29
42 46 4 0.51
DBW25117 67 95 28 0.30
-- 103 109 6 0.19
143 182 39 0.15
13 19 6 0.54
DBW-25-120 89 144.5 55.5 0.15
164 172 8 0.46
DBW-25-108 10 51 41 0.20
106 153 47 0.14
14 20 6 0.19
37 54 17 0.47
DBW-25-054
including
37 38 1 5.94
64.3 66 1.7 0.57
79 86 7 1.01
72.2 78 5.8 0.18
DBW25148 86 102 16 0.17
-- 119 139.7 20.7 0.17
169
190
21
0.33
  • and therefore are considered relative rather than true widths.

  • 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 .

discovery, with over 5.3km of strike now tested and supported by more than 40,000m of drilling. Our team is rapidly defining what is emerging as an exceptionally large, near-surface, structurally controlled copper sulphide deposit” stated COO, Kevin Bonel.

“We are developing a clear understanding of Dumbwa and can see the hallmark ‘pinch-and-swell’ geometry typical of major structurally controlled systems and have confirmed unequivocally that Dumbwa is a basement-hosted, strain-related deposit, geologically comparable in every way to Barrick’s Lumwana. We also recognize a predictable grade distribution along strike, with broader higher-grade zones separated by narrower lower-grade domains. Most importantly, we are continuing to establish meaningful scale with each step north expanding the system and

mineralisation remaining open, alongside a clear plan to unlock additional mineralisation within zones identified through earlier drilling.”

Figure 1: Dumbwa drilling to date, plotted on 11.2km Phase One copper-in-soil anomaly, target area.

soil anomaly, target area.

The Company’s drilling has now surpassed 200 holes for a total of more than 42,000m over 5.3km of strike, and continues to confirm that Dumbwa is an exceptionally large, very near surface, structurally controlled copper sulphide deposit which remains open for growth. Drill testing has focussed on the upper ~220m of the deposit with the intent of defining a resource amenable to rapid, low strip ratio, lowcost future development. It is noted that some areas of similar mineralisation at the nearby Lumwana project can be traced to vertical depths well beyond 200m. At Dumbwa, east-west width of the mineralised corridor ranges from 200m to greater than 500m. Copper grades are variable ranging from thick lower grade intercepts (> 50 m @ <0.3%) to thick higher-grade intercepts (>25m@>0.5%). Grade variability is pronounced along strike (north-south) and is influenced by cross-cutting northwestsoutheast structures that adversely affect the strain regime and subsequent development of mineralised schists. In contrast, grades are relatively consistent eastwest within the higher, medium and lower grade zones, and across the width of the mineralised corridor.

Figure 3: Assay grade shells superimposed on the Dumba soil anomaly showing the correlation between high soil anomalies and medium to high grade mineralised intercepts at Dumbwa. Drilling continues to follow the soil anomaly north.

The First 5.3km Of Strike – In Detail

starts at the south concession boundary and is approximately 1,800m long, varying from 200m wide to more than 500m wide in places, with scope to increase the known mineralised envelope eastwards and at greater depth.

This is followed by a lower grade zone (“CF Block 1”) ~900m along strike and again averaging around 200m wide. Here the strain in the gneisses is observed as lower and consequently there was poor schistose lens development and weaker mineralisation, although the mineralisation remains persistent along strike.

This lower grade zone transitions into the next higher-grade portion of the deposit (the “ES Block”) which, to date, has been extended for 1,600m along strike at an average width of ~500m, expanding it to over twice the width of the southernmost higher-grade zone.

3,300m with widths varying from 200m to over 500m.

In both higher-grade zones, mineralisation depth extent has been demonstrated to start at surface and reach between 175m and 220m deep, with occasional deeper holes demonstrating mineralisation continuing to a depth greater than 300m.

Structurally, the southern part of the Dumbwa copper deposit is weakly broken by late NW-SE trending structural corridors (late brittle faulting) although offset distances are minimal. Early observations on drill core from the area north of strike kilometre 5, the area currently being tested by drilling, indicates more intense late brittle faulting and locally larger offsets, however, the relationship between high strain leading to copper mineralised schist development holds true.

Figure 4: Long Section showing 4km mineralised strike and distribution of bornite and chalcopyrite.

Detailed lithological and structural logging is showing the Dumbwa copper deposit to be a stacked series of horizontal to shallow east dipping copper sulphide mineralised biotite and biotite-muscovite schists (“2 mica schists”) within a barren grey and pink basement gneiss sequence. The schists form in an intimate relationship with strain which has resulted in the schists being variably developed over the 5.3 km that have been drilled to date. Simply put, increasing strain leads to greater schist development, which in turn results in higher copper sulphide concentration.

The relationship between high tectonic strain and the evolution of the copperbearing schists is very clear, and the similarity between Lumwana and Dumbwa has been well established.

As with Lumwana, where there is both high strain and mineralised schist, a kyanitic overprint is commonly observed and these correlate with the highest grades and thickest copper intercepts observed in Dumbwa.

Dumbwa and Lumwana share extraordinary geological similarity, formed by the same basement-hosted structural and mineralisation processes:

Lumwana Dumbwa
Copper sulphide mineralised biotite
and muscovite-biotite schists within
agreyandpinkgneisspackage
Copper sulphide mineralised biotite
and muscovite-biotite schists within
agreyandpinkgneisspackage
Host rocks ancient basement
gneisses
Host rocks ancient basement
gneisses
Copper mineralisation related to
high strain and the evolution of
schists as a C1 fabric
Copper mineralisation related to
high strain and the evolution of
schists as a C1 fabric
Copper mineralisation dominated by
chalcopyrite with bornite and
subordinate chalcocite
Copper mineralisation dominated by
chalcopyrite with bornite and
subordinate chalcocite
Lumwana dominated by shallow
dipping (south and east) mineralised
schists
Dumbwa dominated by shallow
(mostly east) dipping mineralised
schists
Lumwana mineralised schists
anastamosed and intercalated with
barren grey gneiss as ‘boudins and
rafts’
Dumbwa mineralised schists
anastamosed and intercalated with
barren grey gneiss as ‘boudins and
rafts’
Subsidiary sulphides dominated by
pyrite (Chimiwungo) and pyrrhotite
(Kamisengo)
Dumba dominated by subsidiary
pyrite and rare pyrrhotite
Lumwana mineralised schists usually
associated with a metasomatic
kyanite overprint
Dumbwa mineralised schists usually
associated with a metasomatic
kyanite overprint
Lumwana Chimiwungo
mineralisation extends for >4km
east-west and >5km north-south,
with a shallow dip to the south. It is
sheeted, continuing beyond these
limits, with grades and thicknesses
decreasingawayfrom the core of the
The Dumbwa deposit extends for
200m – 500m east-west and at least
5.3km north-south with planned
Phase One exploration drilling to test
a further 5.7km north for a total of
11.2km of suspected north-south
copper mineralised strike. Phase Two
deposit. This mineralisation is still
open to the east and south but
pinches out to the west and is down-
thrown by a series of late-stage,
north-dipping, normal faults. The
main body of the Chimiwungo
will test the northern half of the
20km copper-in-soil anomaly.
Stacked mineralised zones go from
surface to beyond 300m but average
~175m – 200m.
deposit consists of multiple stacked
mineralised zones, in aggregate
varying from 40m to over 100m in
thickness (Source: Porterhouse)
While drilling to date demonstrates
Dumbwa having a narrower E-W
mineralised corridor (200m-500m
wide) when compared to Lumwana,
the deposit remains open and has
the potential for signifcantly
greater strike length and maximum
thickness than Lumwana.

Figure 5: Cross Section through Kamisengo – Lumwana (Source: 2024 Barrick NI-43-101 Technical Report).

Figure 6: Cross section through Dumbwa – Line 100N demonstrating the strong similarity with the geology and mineralisation at Lumwana

Laboratory Issues Resolved

In early February 2026, the Company encountered quality control issues with core sample assays at SGS Laboratories in Kalulushi, Zambia. These persisted across multiple batches, creating a significant backlog of assay results. SGS conducted internal audits of their laboratory and systems, which identified several contributing factors, including ICP instrument calibration issues, poor-quality argon gas supply, and complications arising from a facility relocation.

Through rigorous quality assurance and quality control (“QA/QC”) protocols, Midnight Sun identified these issues as they emerged and, through persistent communication, worked with the laboratory to resolve them. SGS has since remedied the issues, with assay results now meeting Midnight Sun’s internal QA/QC standards. With the issues now resolved, the associated assay backlog has been substantially

alleviated. Of the 200 holes drilled to date, including ongoing holes that have not yet been sampled, assay results for 66 holes remain pending.

The Company has also been working with Intertek Laboratories, and has dispatched recent samples for assaying to Intertek in Perth, Australia.

Dumbwa – Continued Expansion

Detailed geological cross-sections of assay results, lithologies, and structures have indicated that some of the early drill fences located in the south part of the Dumbwa copper deposit were stopped short of fully testing the mineralised width, particularly in the southernmost high-grade zone. Further drilling is planned to test these incomplete drill fences with the expectation that the southern mineralised zone will grow eastwards, having potential to add materially to the overall deposit size.

As of this news release, the initial, broadly spaced, shallow drilling has tested approximately one third of the strike extent being targeted in the Phase One program (with assay results released for the first 4km) . Drilling will continue along the planned strike length of 11.2km in Phase One with a further 200 holes planned for an additional 40,000m of drilling, including width extensions on certain previously drilled fences.

Figure 7: Planned drill holes to extend mineralised width of fences.

The Dumbwa deposit remains open to the north along the entire extent of the continuous copper-in-soil anomaly, to the east in certain areas, and to depth. Exploration work at Dumbwa, including drilling, is expected to continue on an ongoing basis.

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 200micron plastic bag, assigned a unique sample number, and recorded into GeoSpark logging system. Samples always remained under the supervision of Midnight Sun staff to maintain chain of custody. All samples were then delivered to SGS Labs located in Kalulushi, Zambia, a fully accredited laboratory. Once received, the samples were sorted, dried, crushed, and pulverized (SGS code PRP90) followed by four-acid digest with ICP-OES finish (SGS Code ICP42S). Copper range of detection is 0.01-10%. Midnight Sun follows an in-house QA/QC program that consists of a random insertion every 10th sample of either a coarse blank, fine blank, coarse duplicate, fine duplicate, or Certified Reference Material (standards).

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-

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 just west of our project 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 new 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: [email protected]

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, 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.

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 forwardlooking 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, geological similarities or characteristics are not guarantees or certainties of successful exploration. 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

required by law.