ATERRA Mobilizes Diamond Drill Rig to the Totora Cu/Au Project and Announces Grant of Options

ATERRA Metals Inc. (CSE: ATC) (OTCQB: CSSCF) ("ATERRA") is pleased to report that a diamond drill rig is currently being mobilized onto its Totora CuAu Project to continue the Phase I drill program (Table 1). Diamond drilling will focus on the Totora CuAu porphyry, where a number of recently drilled reverse circulation ("RC") holes, stopped short due to water inflow, will be deepened, and on the Frontera CuAu Deposit, where it will be used to confirm historical RC drill results.

"We are quite excited for the start of the diamond drilling and to see core from the Totora porphyry and Frontera deposit," said Carl Hansen, CEO of ATERRA. "While RC drilling is faster and less expensive, core drilling provides a clearer picture of the nature and relationships of the mineralization, alteration and structural controls within the copper-gold porphyries. Understanding the nature of these relationships is useful in the preparation of a new mineral resource estimate and it is our goal to announce a new estimate during the third quarter of 2026."

Table 1 - Totora Cu/Au Project: Phase I Drill Program

Frontera Cu/Au Deposit

The Frontera Cu/Au Deposit (Figure 1) hosts historic resources (Table 2) of 16 million indicated tonnes grading 0.56% copper equivalent ("CuEq") (0.38% copper and 0.22 grams per tonne gold) and 34 million inferred tonnes grading 0.54% CuEq (0.36% copper and 0.22 grams per tonne gold). The resource estimate was prepared by Hot Chili Limited based on 16,175 metres of drilling completed in 2013. All but 2 holes completed by Hot Chili Limited were RC. ATERRA's diamond drilling will provide significant geological information and confirmatory assay data that is required for the preparation of a new mineral resource estimate.

Table 2 - Frontera Cu/Au Deposit: Historical Resource Estimate (March 2014)*

Figure 1 - Totora Cu/Au Project: Frontera, Taruca, Clinton and Sevilla Properties and Known Cu/Au Occurrences

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Research Capital Advisory Agreement

On March 26, 2026, ATERRA announced that it had engaged Research Capital Corporation ("RCC") as a financial advisor for a period of 3 months. In consideration of RCC's engagement, ATERRA will issue RCC a total of 5,750,000 common shares of ATERRA, to be paid in 3 monthly tranches. The first monthly tranche of 1,916,666 shares was issued to RCC on April 27, 2026. The securities were issued at a deemed price of $0.0327 per share for total deemed consideration of $62,674.97. The shares issued are subject to a statutory hold period of 4 months (until August 27, 2026). Upon issuance of the shares to RCC, ATERRA will have 349,957,799 issued and outstanding common shares.

Option Grant

ATERRA announces that it has granted 15,570,000 stock options with 7,970,000 options granted to directors and officers of ATERRA and 7,600,000 options granted to ATERRA consultants. Each option entitles the holder to acquire one ATERRA common share at an exercise price of $0.05 until April 30, 2028.

NI 43-101 Disclosure

Qualified Person: As defined by National Instrument 43-101 ("NI 43-101") of the Canadian Securities Administrators, the "Qualified Person" for ATERRA Metals Inc. is Francisco Bravo, a resident of Santiago, Chile. As ATERRA's Chief Geologist, Mr. Bravo is considered "not independent" as the term is defined by NI 43-101. Mr. Bravo, a Public Registered Person for Reserves and Resources N° 515, in Chile, and registered in the Colegio de Geólogos de Chile under N° 725, has reviewed and approved the technical information contained in this press release.

Copper Equivalent Estimation: Copper equivalent ("CuEq") grades were estimated using a copper price of US$4.00 per pound and a gold price of US$3,500 per ounce (US$112.53 per gram). CuEq grades are estimated using the following formula: CuEq% = ((Au grade * 0.85 * 112.53) / 4.00 / 2,204.6) * 100 + (Cu grade * 0.85).

Regulatory requirements for disclosure of CuEq grade estimates require an estimation of metallurgical recoveries in the situation where no metallurgical testwork has been completed. ATERRA estimates copper recoveries of 85% and gold recoveries of 85%. It is important to note that the actual recoveries will likely vary from those used in the estimation of the CuEq grades.

Historical Results: ATERRA has not undertaken any independent investigation of any historical results from the Totora Project nor has it verified the underlying technical basis for the historical resources and drilling results. The reader is cautioned against relying on the accuracy of the historical results presented; however, ATERRA considers all historical results relevant as those results will be used as a guide to plan future exploration programs: ATERRA considers the data to be reliable for these purposes.

About ATERRA Metals Inc.

ATERRA is a mineral exploration company focused on exploration opportunities in Chile. ATERRA's team of successful exploration professionals is dedicated to the discovery of mineral deposits that can be progressed into economically viable development projects, creating value for all stakeholders.

On behalf of ATERRA Metals Inc.,

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This news release contains forward-looking statements, including predictions, projections and forecasts. Forward-looking statements include, but are not limited to: plans for the evaluation of exploration properties; the success of evaluation plans; the success of exploration activities; mine development prospects; and, potential for future metals production. Often, but not always, forward-looking statements can be identified by the use of words such as "plans", "planning", "expects" or "does not expect", "focus is to", "continues", "scheduled", "estimates", "forecasts", "objectives", "intends", "potential", "anticipates", "does not anticipate", or describes a "goal", or variation of such words and phrases or state that certain actions, events or results "may", "could", "would", "might", or "will" be taken, occur or be achieved.

Forward-looking statements involve known and unknown risks, future events, conditions, uncertainties and other factors which may cause the actual results, performance or achievements to be materially different from any future results, prediction, projection, forecast, performance or achievements expressed or implied by the forward-looking statements. Such factors include, among others: changes in economic parameters and assumptions; all aspects related to the timing of exploration activities and receipt of exploration results including assays; the interpretation and actual results of current exploration activities; changes in project or exploration parameters as plans continue to be refined; the results of regulatory and permitting processes; future metals prices; possible variations in grade or recovery rates; variations in the recovery rates used in the calculation of equivalent grades; failure of equipment or processes to operate as anticipated; labour disputes and other risks of the mining industry; the results of economic and technical studies; delays in obtaining governmental approvals or financing or in the completion of exploration; as well as those factors disclosed in ATERRA's publicly filed documents.

Although ATERRA has attempted to identify important factors that could cause actual actions, events or results to differ materially from those described in forward-looking statements, there may be other factors that cause actions, events or results not to be as anticipated, estimated or intended. There can be no assurance that forward-looking statements will prove to be accurate, as actual results and future events could differ materially from those anticipated in such statements. Accordingly, readers should not place undue reliance on forward-looking statements.

Neither the Canadian Securities Exchange nor its regulation services provider has reviewed or accepts responsibility for the adequacy or accuracy of the content of this news release.

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