Sendero Resources drills at Peñas Negras; confirms geological model in Vicuña Belt

Sendero Resources Reports Drilling Results at Peñas Negras Project; Confirms Geological Model and Identifies Geochemical Vectors in Vicuña Belt, Argentina

(TheNewswire)

Vancouver, British Columbia – TheNewswire - (August 17, 2026) – Sendero Resources Corp. (TSXV: SEND)(FSE:04O) (the “Company” or “Sendero”) is pleased to report drilling results from the 2026 reconnaissance diamond drilling and rock sampling program at its 100%-owned Peñas Negras Project, La Rioja, Argentina. The Company’s porphyry-epithermal geological model was confirmed by the three drillholes totalling 396.3 metres on the southwestern margin of the target area and 453 rock samples collected across the property to generate new prospective areas and guide future drilling programs .

HIGHLIGHTS

Near surface gold and silver mineralization return by all three drillholes;

Gold and silver mineralization confirmed by three reconnaissance holes, with PNDH-201 returning 1.04 g/t Au over 1.5 m from 14.0 m within a broader halo of elevated gold grades extending from surface to 46.0 m (returning a weighted average of 0.11 ppm Au);

Strong silver anomalies in all three drillholes , including 48 g/t Ag over 1.5 m from 14.0 m and 28.2 g/t Ag over 1.0 m from 57.0 m in PNDH-201;

Multiple pathfinder elements – Sb, As, Cu, Mo, Pb, and Zn – reinforce the presence of a significant hydrothermal system and will play in important role in realigning the following exploration campaign at Peñas Negras;

An extensive leached cap, considered an integral part of a significant high-sulfidation epithermal system, identified in all three diamond drillholes; the full lateral and vertical extent of this system is yet to be determined and represents a significant exploration target in its own right;

Exceptional surface geochemistry across the property, with rock samples returning up to 4.82 g/t Au and 18.00 g/t Ag in the PN-NNW geochemical target area – approximately 9 km NNW of the drilling area, highlight the potential scale of the underlying mineralized hydrothermal system and further support the Company’s geological model;

The Company is fully funded to continue diamond drilling at Peñas Negras and plans to target the hydrothermal system in the target area along the Mogotes Fault framework.

“These results provide strong validation of our geological model for Peñas Negras. This important step forward in defining the district scale potential of our strategic land package. We are especially pleased that the intermediate intrusive and volcanic host rocks, alteration, pathfinder geochemistry, stockwork veining, and Mogotes Fault structural framework are all consistent with the characteristics of the world-class high-sulfidation epithermal and porphyry systems that host the Vicuña Project deposits, located less than 15 kilometres to the south-southeast, said Alex Gostevskikh, CEO of Sendero Resources . “The three holes completed to date, together with historical Anglo American drilling, confirm the presence of a substantial high-sulfidation epithermal system, although its full dimensions remain to be defined. Importantly, the leached cap and emerging geochemical vectors support our thesis that a deeper porphyry copper-gold system may lie beneath the priority target area, with an extensive auriferous zone of advanced argillic alteration located immediately to the north-northeast. We are very encouraged by the results of our rock sampling program, which suggest that the target area may extend significantly farther to the north and northwest.”

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Fig.1. Regional setting of the Penas Negras Project area

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Fig. 2. District geology of the Penas Negras Project

Rock Sampling Program

The Company completed the 2026 rock-sampling program comprising 453 samples across the property, which returned up to 4.82 g/t Au and 18 g/t Ag at the PN-NNE geochemical prospect area, approximately 9 kilometres to the north-northeast of the area where drilling took place. In addition, exceptionally anomalous gold samples – up to 1.65 g/t Au, came from the PN-NW area, approximately 6.5 km to the NNW. In the southwest, where the drilling was being done, the rock sampling returned up to 5.13 g/t Ag. The geochemical signature and alteration patterns indicate the presence of a potential district-scale epithermal/porphyry system beneath the leached cap and colluvial overburden.

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Fig. 3. Sendero 2026 rock sampling and anomalous Au results.

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Fig. 4. Sendero 2026 rock sampling and anomalous Ag results.

2026 Reconnaissance Drilling Program

The reconnaissance drilling program targeted the southwestern extents of the inferred Mogotes structural corridor. The Company completed drilling of three diamond drillholes totalling 396 meters, from which hole PNDH-201 returned 1.04 g/t Au over 1.5 m from 14.0 m within a broader halo of elevated gold values extending from surface to 46.0 m (returning a weighted average of 0.11 ppm Au for this interval) . All three holes returned anomalous silver values including 48 g/t Ag over 1.5 m from 14.0 m and 28.2 g/t Ag over 1.0 m from 57.0 m in PNDH-201. True widths are unknown at this stage.

Fig. 5. Map identifying Sendero 2026 drillhole locations in the south-southwestern margin of the target area within its 100%-owned Peñas Negras Project.

Hole PNDH-203 confirmed the presence of the Mogotes Fault further confirming the Company’s geological model and mineralization being associated with the structural framework of the Vicuna Belt. The hole also returned anomalous antimony values further supporting the thesis for high-sulfidation epithermal mineralization.

* Reported coordinates are handheld-GPS easting, northing, and elevation and subject to future instrumental surveys.

The geochemical patterns identified in all three holes—and particularly the distinct antimony anomaly in PNDH-203—provide an important vector toward this deeper target. With approximately 3.0 kilometres of the prospective Mogotes structural corridor remaining untested, Sendero is well positioned to advance Peñas Negras during the upcoming drilling season.

Upcoming Program

The next drilling campaign will focus on defining the internal architecture of the fertile hydrothermal system within the Mogotes structural corridor, while further advancing the newly identified geochemical targets at PN-NNW and PN-NNE, where rock sampling returned exceptional gold and silver values. These new geochemical targets now extend the potential mineralized system for up to 9 kilometres along strike.

Corporate Update

Sendero Resources is funded to continue diamond drilling at Peñas Negras in the upcoming 2026–2027 exploration season. The planned program will target the hydrothermal system which has been observed during the 2026 drilling campaign and internal structure of the Mogotes Fault framework. All of the Company’s exploration licenses are in good order and in full compliance with the applicable concession terms. The Company is delighted to enjoy the support of the Government of La Rioja, which has expressed its commitment to supporting Sendero Resources and future exploration at Peñas Negras. This support reflects the provincial government’s recognition of the geological potential of the Peñas Negras district and its confidence in the Company’s approach to responsible exploration. The Company looks forward to continuing to work constructively with provincial and local stakeholders as it advances the project.

About Sendero Resources Corp.

The Company is focused on copper-gold exploration at its 100% owned Peñas Negras Project in the Vicuña Belt in Argentina. The Peñas Negras Project has similar geological characteristics to other deposits in the Vicuña Belt and multiple porphyry and high-sulfidation epithermal targets have been identified on the project. The Company’s target area is located approximately 12 km north-northeast of the Josemaria resource area, while the centre of the Peñas Negras concession area is situated approximately 18 km southeast of Caserones mine operated by Lundin Mining, approximately 24 km northeast of NGEx Minerals’ Lunahuasi project, and about 32 km north-northeast of BHP-Lundin Mining’s Filo del Sol development stage project. The Company also has an option to earn an 100% interest on eight additional granted mining concessions covering 91.7 km 2 . The total project area comprises 211.77 km 2 .

Qualified Person

Steven McMullan, P. Geo., a consultant to the Company and member of the Board supervised the preparation of and reviewed and approved the scientific and technical information pertaining to Peñas Negras Project contained in this news release. Mr McMullan is a qualified person as defined by National Instrument 43-101 Standards of Disclosure for Mineral Projects.

Samples were cut at Sendero Resources’ operations facility in La Rioja, Argentina by Company personnel. The HQ-size diamond drill core was sawn and sampled at maximum 2-meter intervals, while observing geological contacts.

Both core and rock samples were bagged, tagged, sealed, packaged, and transported by Company’s geologists to the SGS sample preparation laboratory in San Juan, Argentina where they were crushed and an approximately 200 g split was pulverized to 85% passing 140 mesh. The prepared sample splits were sent to the SGS assay laboratory in Callao, Peru for gold and silver assays, and multielement ICP. The SGS testing laboratory in Callao, Peru, holds ISO/IEC 17025 accreditation through the American Association for Laboratory Accreditation (A2LA) and is independent of the Company. Both core and rock samples were assayed for gold by fire assay fusion with AAS finish on a 50 g sample (FAA515) and multielement suite was assayed by the ICM40B method – Inductively Coupled Plasma – Mass Spectrometry following a four-acid “near-total” digestion. Samples returning > 10 g/t gold are to be re-assayed by fire assay with gravimetric finish on a 30 g sample (Au-GRA21). Certified reference materials (standards), blank samples, and field duplicates (quarter core samples) were inserted into sampling stream at a rate of approximately 8%. The Company’s QA/QC protocols have not identified quality problems requiring further action.

Further Information

For further information, please contact:

Sendero Resources Corp,

Alex Gostevskikh, Chief Executive Officer

Email: info@senderoresources.com

+1 (236) 232-0988

Follow Sendero Resources (@SenderoRes ) on X, ( ) on LinkedIn, and (@sendero_resources ) on Instagram.

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This press release contains “forward-looking information” and “forward-looking statements” (collectively, “ forward-looking statements ”) within the meaning of applicable Canadian securities legislation. All statements, other than statements of historical fact, are forward-looking statements and are based on expectations, estimates and projections as at the date of this press release. Any statement that involves discussions with respect to predictions, expectations, beliefs, plans, projections, objectives, assumptions, future events or performance (often but not always using phrases such as “expects”, or “does not expect”, “is expected” “anticipates” or “does not anticipate”, “plans”, “budget”, “scheduled”, “forecasts”, “estimates”, “believes” 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. Forward-looking statements are necessarily based upon a number of estimates and assumptions that, while considered reasonable, are subject to known and unknown risks, uncertainties, and other factors which may cause the actual results and future events to differ materially from those expressed or implied by such forward-looking statements. There can be no assurance that such statements will prove to be accurate, as actual results and future events could differ materially from those anticipated in such statements. Readers should not place undue reliance on the forward-looking statements and information contained in this press release. Except as required by law, the Company does not assume any obligation to update the forward-looking statements of beliefs, opinions, projections, or other factors, should they change, except as required by law.

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August 17, 2026 - 4:30 AM PDT

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