Highlights

Hole PNDH-06 intersected 44 metres grading 1.23% CuEq within 236 metres of 0.57% CuEq

Hole PND-02 intersected 43.6 metres grading 1% CuEq within 208 metres of 0.56% CuEq

Hole PNR-30 intersected 18 metres grading 1.26% CuEq within 161 metres of 0.54% CuEq

Hole PNDH-03 intersected 62 metres grading 0.66% CuEq within 268 metres of 0.49% CuEq

Hole PNDH-04 intersected 52 metres grading 0.61% CuEq within 266 metres of 0.48% CuEq

Hole PNR-03 intersected 52 metres grading 1.26% CuEq within 68 metres of 1.15% CuEq

Hole PNR-28 intersected 32 metres grading 1.95% CuEq within 102 metres of 0.93% CuEq

Vancouver, British Columbia – (September 23, 2026) – TheNewswire - Sendero Resources Corp. (TSXV: SEND) (FSE:9O40) (the “Company” or “Sendero”) is pleased to report a review and the recalculation of Metal Equivalents on historical drilling on the Peñas Negras copper-gold project in La Rioja province, Argentina.  The Company has rebuilt the database from historical drill programs conducted by notable prior owners and operators evaluating 77 holes and 6,433 assay samples. Applying one consistent CuEq methodology across the entire historical database provides a broader, project-wide view of the project.  

"For the first time, we have a consistent, project-wide depiction of the historical drilling at Peñas Negras, reinforcing why we're so excited about this project," said Jeremy Gillis, Interim CEO of Sendero. "Mineralization begins near surface and extends to more than 350 metres downhole, highlighted by 24 metres of 1.53% CuEq in PNDH-06. This work brings the full value of decades of prior exploration into focus, and we look forward to what is to come from our fully funded drill program."

Copper Equivalent (CuEq) values shown in the tables for drill intercepts are calculated on the basis of US$4.50/lb for Cu, US$3,375/oz for Au, US$60/oz for Ag, US$25/lb for Mo, US$1440/t for Pb and US$2940/t for Zn, with 100% recoveries assumed for all metals (since it is unclear what metals will be the principal products, assuming different recoveries is premature at this stage). The formula is: CuEq = Cu % + (Au grade in g/t x (Au recovery / Cu recovery) x [Au price ÷ 31] / [Cu price x 2200 x 1%]) + (Ag grade in g/t x (Ag recovery / Cu recovery) x [Ag price ÷ 31] / [Cu price x 2200 x 1%]) + (Mo grade in % x (Mo recovery / Cu recovery) x [Mo price] / [Cu price]) + (Pb grade (%) × (Pb recovery / Cu recovery) × [Pb price ÷ (Cu price × 2200)]) + (Zn grade (%) × (Zn recovery / Cu recovery) × [Zn price ÷ (Cu price × 2200)]).The 100% recovery assumption is for illustrative purposes only and actual future recoveries may differ. Reported intervals are drill-indicated (downhole) lengths and insufficient data are currently available to state the true thickness of the mineralized intervals.

Disclosures

Historically on the Peñas Negras project, Metal Equivalents were reported in AuEq, but this exercise is calculated for CuEq as copper is more widely dispersed and is less variable in the project area. Metal Equivalent Grades are calculated from multi-element geochemical analyses of drill core, based on the combination of the primary metal grade with the relative price and metallurgical recovery of secondary metals in a polymetallic geological occurrence. Metal Equivalents (MEqs) simplify reporting of metal grades and are useful for comparison of drill intercepts within a specific project to guide exploration, or for comparison of grades in separate analogous deposits.

Given the considerable increase in commodity prices since 2021 when Sendero Resources Corp acquired the project, recalculation of the MEq is considered important to assign a more realistic value to drill intercepts. Metal Equivalent calculations are used with caution and are generally not acceptable for public disclosure in mineral resource estimates.

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.

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 a 100% interest on eight additional granted mining concessions covering 91.7 km2. The total project area comprises 211.77 km2.

Further Information

For further information, please contact:

Sendero Resources Corp.
Jeremy Gillis, Interim Chief Executive Officer
Email: info@senderoresources.com

+1 (236) 232-0988         

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

Cautionary Statement on Forward-Looking Information

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.

Cautionary Statement

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 release.

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