The Catalyst Cluster: GR Silver Mining's Fully Funded Pathway to a 2027 Economic Study

• GR Silver Mining trades at US$1.65 per in-situ silver ounce versus a peer mean of US$3.43 per ounce, despite a 134-million-ounce silver-equivalent resource, due to the absence of a formal economic study.
• The company is fully funded with C$28.5 million in cash and no debt, supporting four planned catalysts: a 20,000-metre drill program, Bulk Sample Test Mining, an updated Mineral Resource Estimate (MRE), and a maiden Preliminary Economic Assessment (PEA).
• San Marcial's average 22-metre true-width hydrothermal breccia mineralisation has delivered a historical discovery rate of more than 4,000 silver-equivalent ounces per metre drilled at a discovery cost of CAD$0.17 per ounce of silver.
• The active 20,000-metre drill program is targeting untested mineralisation at San Marcial, returning 45.1 metres true width at 1,623 grams per tonne silver, including 8.25 metres at 8,579 grams per tonne silver.
• Mexico's environmental regulator confirmed no new Manifestación de Impacto Ambiental (MIA) is required for the former Plomosas Mine, allowing Bulk Sample Test Mining (BSTM) to advance while supporting a targeted MRE update in the second half of 2026 and a PEA in the first half of 2027.

Why the Discount Exists & What Closes It

GR Silver Mining's (TSXV: GRSL | OTCQX: GRSLF | FRA: GPE) trades at an enterprise value (EV) of US$1.65 per in-situ silver-equivalent ounce versus a peer average of US$3.43 per ounce, despite a 134-million-ounce silver-equivalent resource defined in the 2023 National Instrument 43-101 Mineral Resource Estimate. The valuation gap largely reflects the absence of a Preliminary Economic Assessment  (PEA) that includes a net present value (NPV) and an internal rate of return (IRR), key metrics used to value development-stage mining projects.

The four catalysts the company is advancing - a 20,000-metre drill program, a Bulk Sample Test Mining program at Plomosas, an updated Mineral Resource Estimate (MRE), and a maiden Preliminary Economic Assessment targeted for the first half of 2027 - to establish that economic framework. With C$28.5 million in cash and no debt as of May 29, 2026, GR Silver Mining is funded to execute all four programs without disclosed near-term equity financing.

The Capital Efficiency Advantage at San Marcial

San Marcial's average 22-metre true-width hydrothermal breccia mineralisation underpins a discovery cost of CAD$0.17 per ounce and a historical discovery rate exceeding 4,000 silver-equivalent ounces per metre drilled, more than double the peer average.

Interim President and Interim Chief Executive Officer of GR Silver Mining, Eric Zaunscherb, quantified the operational implications:

"What's very unusual about San Marcial, aside from the exceptional grades, is the thickness. Unlike many other companies, we're not chasing epithermal veins that are 1, 2, 3 metres wide. What we have is a hydrothermal breccia, blasted rock on the shoulders of an intrusive body, and from our 2023 resource, we're able to say that the average thickness is 22 metres. That has two impacts. One, ultimately, when you're mining, you could use very highly efficient long hole open stoping, for example."

Catalyst 1: The 20,000-Metre Expansion Program

The 20,000-metre step-out drill program targets the 80% of the San Marcial chargeability anomaly that remains untested, as well as newly identified parallel breccia zones adjacent to the main mineralised body. As of May 22, 2026, three rigs were active on site with program completion targeted in the second half of 2026 - the gating event for the MRE update and, by extension, the first-half-2027 PEA.

The highest-grade intercept in the company's history returned 45.1 metres true width at 1,623 grams per tonne silver from 267.85 metres down hole, including 18.85 metres true width at 3,846 grams per tonne silver with 0.7% lead and 2.5% zinc, and 8.25 metres true width at 8,579 grams per tonne silver with 1.6% lead and 5.5% zinc, as announced May 19, 2026. Management stated the result supports its targeting model for the remaining drill holes.

With approximately 4,000 metres drilled of the planned 20,000 metres and 3 holes reported of an estimated 50, the program represents the primary source of near-term news flow. Security and access conditions remain the primary factors influencing drill completion timelines. 

Catalyst 2: The Plomosas Bulk Sample Test Mining Program

The Bulk Sample Test Mining program (BSTM) at Plomosas serves two functions in the first half of 2027, ahead of the targeted PEA. First, management believes operating activity at Plomosas can help build the social licence needed to accelerate permitting at San Marcial by one to two years. Second, throughput data from the pilot plant will provide observed metallurgical recovery rates, reducing uncertainty in the economic model.

On May 22, 2026, Mexico's Secretariat of Environment and Natural Resources (SEMARNAT) confirmed that no new Environmental Impact Authorisation is required for the former Plomosas Mine, removing a major permitting hurdle. The company stated that only secondary permits remain in progress, allowing the BSTM program to advance toward pilot-scale operations.

Zaunscherb addressed the permitting compression rationale:

"San Marcial, however, is an exploration permit, and for that to reach cash flow, you have to go through all the steps, of course, technical studies and permitting for a new operation. We believe, however, that in gaining social license by putting Plomosas, putting on site a plant, a pilot plant, that we can accelerate that process, and we hope, and by a year or two, that is a huge impact on NPV for sure."

The pilot plant is targeting a throughput of 60 to 200 tonnes per day, subject to safety, security, and secondary permitting conditions.

Catalysts 3 & 4: MRE Update & Maiden PEA

The updated MRE, targeting the second half of 2026, will incorporate step-out drill results from the 20,000-metre program into a revised resource model for San Marcial. That updated model feeds directly into the maiden PEA, targeting the first half of 2027, which will be the first document to integrate the San Marcial and Plomosas areas into a single economic model with a formal NPV and IRR. Those two outputs are precisely the metrics that underpin the US$ 3.43-per-ounce peer-mean valuation at which GR Silver Mining does not currently trade. 

Zaunscherb commented on the sequencing and pacing of the drill program:

"Because we have a 20,000-meter drill program ongoing, we have three rigs on site, we're about 4,000 metres into that, and we've reported three holes out of an estimated 50 out of the program. So there's lots of news flow to come. Now, the security situation in Sinaloa is such that one has to recognise the risk associated with that. We will not put our employees or our contractors in any danger, so we work appropriately, and so we'll see how long it takes to do that program. That will then dictate the pace at which we can deliver a resource update and the pace at which we can deliver a PEA."

The Investment Thesis for GR Silver Mining

• GR Silver Mining trades at US$1.65 per in-situ silver ounce against a peer mean of US$3.43 per ounce on a measured, indicated, and inferred basis, a valuation gap that exists in the absence of a formal net present value despite the 134-million-ounce silver equivalent resource base defined in the 2023 mineral resource estimate.
• The average 22-metre true width of the San Marcial hydrothermal breccia mineralisation has produced a historical discovery rate of over 4,000 ounces silver equivalent per metre drilled, more than double the peer average of approximately 2,000 ounces per metre, at a cost of discovery of CAD$0.17 per ounce of silver.
• A ruling from the Secretaria de Medio Ambiente y Recursos Naturales confirmed on May 22, 2026, that no new Manifestación de Impacto Ambiental is required for the former Plomosas Mine, allowing the Bulk Sample Test Mining program to advance under secondary permitting only and supporting the company's stated expectation that Plomosas operational activity could compress the San Marcial permitting timeline by 1 to 2 years.
• The company holds C$28.5 million in cash with no debt as of May 29, 2026, providing the capital to execute the 20,000-metre drill program, Bulk Sample Test Mining, mineral resource estimate update, and Preliminary Economic Assessment without disclosed near-term equity financing.
• Completion of the first-half-2027 Preliminary Economic Assessment would establish the first integrated net present value and internal rate of return for the San Marcial and Plomosas assets, providing the standardised economic metric that underpins the US$ 3.43-per-ounce peer-mean valuation, which is not currently reflected in GR Silver Mining's US$ 1.65-per-ounce enterprise value.

The 4 catalysts are sequenced to produce one outcome: a formal economic study with a net present value, against which the market can reprice a 134-million-ounce silver-equivalent resource currently valued at US$1.65 per ounce. Drill program completion in the second half of 2026 gates the mineral resource estimate update; the mineral resource estimate update gates the first-half-2027 Preliminary Economic Assessment. Access conditions in the Sinaloa-Durango region are the primary variable affecting whether that sequence holds.

TL;DR

GR Silver Mining trades at US$1.65 per in-situ silver ounce against a peer mean of US$3.43 per ounce, with a 134-million-ounce silver-equivalent resource and C$28.5 million in cash and no debt. The valuation gap exists in the absence of a formal economic study. An updated MRE is targeted for the second half of 2026 and a maiden PEA for the first half of 2027. Drill program pace and Sinaloa-Durango access conditions are the key variables affecting that timeline.

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