UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 6-K

Report of Foreign Private Issuer

Pursuant to Rule 13a-16 or 15d-16

of the Securities Exchange Act of 1934

For the month of May, 2026.

Commission File Number 33-99720

ARAUCO AND CONSTITUTION PULP INC.

(Translation of registrant’s name into English)

Indicate by check mark whether the registrant files or will file annual reports under cover Form 20-F or Form 40-F.

Form 20-F  ☒                  Form 40-F  ☐

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1):  ☐

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7):  ☐

Indicate by check mark whether the registrant by furnishing the information contained in this Form is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.

Yes  ☐                  No  ☒

If “Yes” is marked, indicate below the file number assigned to the registrant in connection with Rule 12g3-2(b): 82-☐

ARAUCO AND CONSTITUTION PULP INC

TABLE OF CONTENTS

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

RATIO ANALYSIS OF THE CONSOLIDATED FINANCIAL STATEMENTS

1. ANALYSIS OF FINANCIAL POSITION

The principal components of assets and liabilities at the end of each period are as follows:

As of March 31, 2026, total assets increased by MU.S.$ 624 compared to December 31, 2025, equivalent to a 2.93% increase. This variation was driven mainly by an increase in Cash and cash equivalents, Other financial assets, and Property, plant and equipment, due to the obtaining of new borrowings, and the valuation of derivative instruments entered into by Arauco to hedge exposure to foreign exchange risk in Brazilian real (BRL), all associated with the progress of the Sucuriú project.

In turn, total liabilities increased by MU.S.$ 531 mainly driven by an increase in financial liabilities, due to borrowings from financial institutions and an increase in lease liabilities, which was partially offset by lower accounts payable balances.

The main financial and operational indicators related to the statement of financial position as of the dates and for the periods indicated below are as follows:

⁽¹⁾: Annual average.

As of March 31, 2026, the short-term debt to total debt ratio represented 16% of total liabilities (17% as of December 31, 2025).

Our financial expenses coverage ratio decreased from 0.66 to 0.36, mainly due to increase in the loss before income tax for the period ended March 31, 2026, compared to the loss before income tax for the same period of 2025.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

b) Statement of profit or loss

Profit before income tax

We recorded a loss before income tax of approximately MU.S.$ (70) compared to a loss of approximately MU.S.$ (34) in the same period of 2025. The variation of MU.S.$ (36) is explained by the factors described in the following table:

The main indicators related to the accounts in our statements of profit or loss and the details of revenues and operation costs are as follows:

⁽¹⁾ : Average earnings per share refer to the profit to net equity to owners of the parent company.

⁽²⁾ : Includes non-controlling interest.

(*) Reflects other non-cash expenses, such as loss of forest due to fires, theft and impairment provisions of industrial property, plant and equipment.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

2. MAIN SOURCES OF FINANCING

Arauco’s financing needs are mainly covered through the capital markets, with bond issuances and credits obtained from banks and financial institutions serving as the main sources of financing.

For short-term borrowing, Arauco follows a liquidity policy which indicates the amounts and institutions from which it can borrow according to several conditions defined in the policy.

In the case of long-term debt, corporate bond issuances in the local market and also in the international markets are used as sources of new resources.

Another source of long-term financing corresponds to borrowings from banks and financial institutions around the world.

3. MARKET SITUATION

Turnover for the first quarter of 2026 decreased by 3.4% compared to the same quarter of 2025, primarily due to lower average pulp prices.

Global pulp inventories have been trending downward since the last quarter of 2025, driven by a decline in short-fiber inventories, partially offset by an increase in long-fiber inventories. However, during the first months of 2026, the above trend has reversed and total inventories have begun to rise, driven by an increase in short-fiber inventories, partially offset by a decline in long-fiber inventories.

In China, during the first quarter of 2026, the pulp market was complex. The printing and writing paper industry saw a decline in demand, compounded by pressures on production costs. The tissue industry faced a challenging environment, characterized by oversupply and lower demand. Regarding pulp prices, long-fiber pulp prices declined mid-quarter, driven by increased supply from Europe and higher local production of long-fiber pulp. On the other hand, short-fiber prices rose throughout the quarter.

In Europe, we observed active demand for pulp during the first quarter of 2026, as a result of reduced pulp supply from other producers. The conflict in the Middle East has impacted the region through higher logistic costs and pressure on energy costs in the Tissue and printing and writing paper industries. Moreover, logistical disruptions have led to a reconfiguration of paper and pulp trade flows, disrupting the two-way exchange between Europe and the Middle East. In terms of prices, short-fiber pulp has shown increases throughout the quarter. This has resulted in rising costs for both the pulp and paper industries.

The textile pulp market saw strong demand and an upward trend in prices during the quarter. The conflict in the Middle East caused an increase in petrochemical product prices, which led to a rise in the price of polyester. In turn, this increase drove the prices of viscose and Lyocell upwards.

Production in the first quarter of 2026 decreased compared to the same period in 2025. During the first quarter of 2026, the scheduled annual maintenance of the Puerto Esperanza mill was carried out.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

Wood Products Business

Sawn timber

In sawn timber, sales for the first quarter of 2026 were lower than in the prior period. Markets in general have experienced weak demand due to low economic growth and low construction activity. Sales were also affected by the war in the Middle East, making sales to that market impossible during March.

In the Remanufacturing segment, the market continues to face sluggish demand, driven by a decline in construction and renovation activity, a trend that has been persistent over the last quarter.

Plywood

Sales for the first quarter of 2026 were lower than in 2025, primarily affected by a decline in production during the summer due to reduced availability of pruned logs, and some markets have shown weaker demand compared to 2025.

Panels (MDF, PB, Melamine)

Sales during the first quarter of 2026, were higher compared to the same period in 2025, driven primarily by a recovery in demand from South American markets.

4. ANALYSIS OF CASH FLOW

The main components of cash flow in each period are as follows:

Our cash flows from operating activities showed a positive balance of MU.S.$ 301 for the current period, an increase of MU.S.$ 30 compared to the previous period (positive balance of MU.S.$ 271 for the same period in 2025), resulting mainly from lower disbursements for payments to suppliers.

The cash flows from financing activities showed a positive balance of MU.S.$ 586 for the current period, an increase of MU.S.$ 610 compared to the previous period (negative balance of MU.S.$ 24 for the same period in 2025). This was mainly due to higher funds from borrowings obtained, partially offset by lower cash outflows for loan repayments.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

The cash flows from investing activities for the current period reflected a negative balance of MU.S.$ 610, representing a negative variation of MU.S.$ 211 compared to the same period in 2025 (which reported a negative balance of MU.S.$ 399 for the same period in 2025). This variation was primarily driven by higher payments for the purchase of property, plant and equipment, and other non-current assets, driven by the Sucuriú project.

5. MARKET RISK ANALYSIS

In respect of the economic risks resulting from interest rate variations, the Company maintained, as of March 31, 2026, a ratio of fixed rate debt to total consolidated debt of approximately 93.1%, which we believe is consistent with industry standards.

Regarding variations in prices of pulp and forestry products, the Company does not participate in futures trading because of its low-cost structure for the industry keeps the risks from price fluctuations bounded.

The Company and most of its subsidiaries maintain their accounting records and prepare their financial statements in U.S. dollars. Most of their revenues (and accordingly accounts receivable) are denominated in U.S. dollars, and most financial liabilities are either denominated in U.S. dollars or are covered by exchange rate swaps. As a result, exposure to exchange rate fluctuations has decreased significantly.

The consolidated financial statements as of March 31, 2026 include a detailed analysis of the risks associated with the business of Arauco (see Note 23).

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

INTERIM CONSOLIDATED STATEMENTS OF FINANCIAL POSITION

The accompanying notes are an integral part of these interim consolidated financial statements.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

INTERIM CONSOLIDATED STATEMENTS OF FINANCIAL POSITION (continued)

The accompanying notes are an integral part of these interim consolidated financial statements.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

INTERIM CONSOLIDATED STATEMENTS OF PROFIT OR LOSS

The accompanying notes are an integral part of these interim consolidated financial statements.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

INTERIM CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME

The accompanying notes are an integral part of these interim consolidated financial statements.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

INTERIM CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY

The accompanying notes are an integral part of these interim consolidated financial statements.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

INTERIM CONSOLIDATED STATEMENTS OF CASH FLOWS

The accompanying notes are an integral part of these interim consolidated financial statements.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

NOTES TO the INTERIM consolidated financial statements as of March 31, 2026 and December 31, 2025

NOTE 1. PRESENTATION OF INTERIM CONSOLIDATED FINANCIAL STATEMENTS

Entity Information

Celulosa Arauco y Constitución S.A. and subsidiaries, (hereafter “Arauco” or the “Company”), tax identification number 93.458.000-1, is a closely held corporation. As it is an issuer of publicly offered securities (bonds), these are registered in the Securities Registry (the “Registry”) of the Chilean Commission for the Financial Market (“CMF”), and the Company is therefore subject to the supervision of said Commission. Additionally, the Company is registered as a non-accelerated filer in the Securities and Exchange Commission (SEC) of the United States of America.

The Company’s head office address is El Golf Avenue 150, 14^th floor, Las Condes, Santiago, Chile.

Arauco is principally engaged in the production and sale of products related to the forestry and timber industries. Its main operations are focused on business areas of pulp and wood products.

As of March 31, 2026, Arauco is controlled by Empresas Copec S.A., tax identification number 90.690.000-9, which owns 99.999916% of Arauco, and is registered in the Securities Registry as No. 0028. Each of the above mentioned companies is subject to the oversight of the CMF.

Moreover, Empresas Copec S.A. is controlled by the public corporation AntarChile S.A., tax identification number 96.556.310-5, which owns 60.8208% of Empresas Copec S.A. Furthermore, the ultimate shareholders of AntarChile S.A. and, consequently, of Empresas Copec S.A., are Mr. Roberto Angelini Rossi, tax identification number 5.625.652-0, and Mrs. Patricia Angelini Rossi, tax identification number 5.765.170-9.

Arauco’s interim consolidated financial statements were prepared on a going concern basis.

Presentation of interim consolidated financial statements

The interim consolidated financial statements presented by Arauco are comprised by the following:

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

Period covered by the interim consolidated financial statements

As of March 31, 2026 and December 31, 2025.

Date of approval of the consolidated financial statements

These consolidated financial statements were approved by the Board of Directors of the Company (the “Board”) at the Extraordinary Meeting No. 758 on May 4, 2026.

Abbreviations used in this report:

IFRS - International Financial Reporting Standards

IASB - International Accounting Standards Board

IAS - International Accounting Standards

MU.S.$ - Millions of U.S. dollars

ThU.S.$ - Thousands of U.S. dollars

U.F. – Inflation index-linked units of account

ICMS – Tax movement of inventories and services (Brazil)

ThCLP$ - Thousands of Chilean pesos

ThR$ - Thousands of Brazilian real

Th€ - Thousands of Euros

Functional and Presentation Currency

Arauco and most of its subsidiaries determined the United States (“U.S.”) dollar as its functional currency since the majority of its revenues from sales of its products are derived from exports denominated in U.S. dollars, while their costs of sales are to a large extent related or indexed to the U.S. dollar.

For the pulp reportable segment, most of the sales are exports denominated in U.S. dollars and costs are mainly related to plantation costs which are settled in U.S. dollars.

For the wood reportable segment, although total sales include a mix of domestic and exports sales, prices of the products are established in U.S. dollars, which is also the case for the cost structure of the related raw materials.

In relation to the cost of sales, although labor and services costs are generally billed and paid in local currency, these costs are not as significant as the costs of raw materials, which are driven mainly by global markets and therefore, influenced mostly by the U.S. dollar.

The currency used to finance operations is mainly the U.S. dollar.

The presentation currency of the consolidated financial statements is the U.S. dollar. Figures on these consolidated financial statements are presented in thousands of rounded U.S. dollar (ThU.S.$).

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

Summary of significant accounting policies

These interim consolidated financial statements have been prepared in accordance with International Financial Reporting Standards (IFRS) as issued by the International Accounting Standards Board (“IFRS Accounting Standards”) and they represent the explicit and unreserved adoption of IFRS.

The interim consolidated financial statements have been prepared on a historical cost basis, except for biological assets and certain derivative financial instruments which are measured at revalued amounts or fair value at the end of each period as explained in the following significant accounting policies.

The interim consolidated statements of cash flows are presented using the direct method.

The preparation of these interim consolidated financial statements, in accordance with IFRS, requires management to make estimates and assumptions that affect the carrying amounts reported. These estimates are based on historical experience and various other assumptions that are considered to be reasonable. Actual results may differ from these estimates. Management believes that the accounting policies below are the critical judgments that have the most significant effect on the amounts recognized in the consolidated financial statements.

- Biological assets

The recovery of forest plantations is based on discounted cash flow models which means that the fair value of biological assets is calculated using cash flows from continuing operations on a discounted basis, based on our sustainable forest management plans and the estimated growth of forests.

The measurement of the fair value of the biological assets is determined using a discounted cash flow model. Our cash flow projections include significant judgments and assumptions relating to discount rates, estimated growth of the forests and sales margins. This valuation is performed on the basis of each identifiable farm block and for each type of tree. The main considerations used to calculate the valuation of forest plantations and a sensitivity analysis are presented in Note 20.

- Litigation and contingencies

Arauco and its subsidiaries are subject to certain litigation proceedings. Future impact on Arauco’s financial condition derived from such litigations is estimated by management, in collaboration with its legal advisors. Arauco applies judgment when interpreting the reports of its legal advisors who provide updated estimates of the legal contingencies at each reporting period and/or at each time a modification is determined to be necessary. For a description of current litigations see Note 18.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

The interim consolidated financial statements include all entities over which Arauco has the power to direct the relevant financial and operating activities. Subsidiaries are consolidated from the date on which control is obtained and up to the date that control ceases.

Specifically, a company controls an investee or subsidiary if, and only if, they have all of the following:

(a) power over the investee, i.e. the investor has existing rights which give it the ability to direct the relevant activities (the activities that significantly affect the investee's returns);

(b) exposure or rights to variable returns from involvement with the investee; and

(c) the ability to use power over the investee to affect the amount of the investor’s returns.

When Arauco holds less than the majority of the voting rights in a company in which it participates, it nonetheless has the power over said company - when these voting rights are enough - to grant it in practice the ability to unilaterally direct said company's relevant activities. Arauco takes into account all facts and circumstances in order to assess if the voting rights in a company in which it participates are enough for granting it the power, including:

a) the size of the investor’s holding of voting rights relative to the size and dispersion of holdings of the other vote holders;

b) potential voting rights held by the investor, other vote holders or other parties;

c) rights arising from other contractual arrangements; and

d) any additional facts and circumstances that indicate the investor has, or does not have, the current ability to direct the relevant activities at the time that decisions need to be made, including voting patterns at previous shareholders’ meetings.

The Company will reevaluate whether or not it holds control of a company in which participates if the facts and circumstances indicate that changes have occurred in one or more of the three elements of control mentioned above.

Consolidation of an investee shall begin from the date the investor obtains control of the investee and cease when the investor loses control of the investee. An entity includes the income and expenses of an acquired or sold subsidiary in the interim consolidated financial statements from the date it gains control until the date when the entity ceases to control the subsidiary.

The profit or loss of each component of other comprehensive income is attributed to owners of the parent company and the non-controlling interest, as appropriate. Total comprehensive income is attributed to the owners of the parent company and non-controlling interests even if the results of the non-controlling interest have a deficit balance.

If a subsidiary uses accounting policies other than those adopted in the interimconsolidated financial statements for transactions and other events in similar circumstances, appropriate adjustments are made to the interim consolidated financial statements of subsidiaries in order to ensure compliance with Arauco's accounting policies.

All intercompany transactions and unrealized gains and losses from subsidiaries have been fully eliminated from these interim consolidated financial statements and non-controlling interest is presented in the interim consolidated statement of financial position within equity.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

The interim consolidated financial statements at the end of this period include the assets, liabilities, income and expenses of the subsidiaries shown in Note 13.

Certain consolidated subsidiaries have Brazilian real, Mexican pesos, Canadian dollars, Chilean pesos and Argentine pesos as their functional currencies. For consolidation purposes, the financial statements of those subsidiaries have been prepared in accordance with IFRS and translated as indicated in Note 1 (e) (ii).

The subsidiaries non-controlling interests in profits or losses and in the equity are presented separately in the consolidated statement of comprehensive income, in the consolidated statement of changes in equity and in the consolidated statement of financial position respectively.

Arauco has defined its reportable segments according to its business areas, based on the products and services sold to its customers. This definition is consistent with the management, resource allocation and performance assessment made by key personnel responsible for making relevant decisions related to the Company’s operation. The personnel responsible for making such decisions is the Chief Executive Officer who is the highest authority for making decisions and is supported by the Vice-presidents of each segment.

Based on the aforementioned process, the Company has established reportable segments according to the following business units:

Refer to Note 24 for detailed financial information by reportable segment.

All items in the financial statements of Arauco and each of its subsidiaries, associates and jointly controlled entities are measured using the currency of the primary economic environment in which each entity operates (the functional currency). The interim consolidated financial statements are presented in U.S. dollars, which is Arauco’s functional and presentation currency.

(ii) Translation to the presentation currency of Arauco

For the purposes of presenting interim consolidated financial statements, assets and liabilities of Arauco’s operations in a functional currency different from Arauco’s are translated into U.S. dollars using exchange rates prevailing at the end of each reporting period. Income and expense items are translated at the average exchange rates for the period, unless exchange rates fluctuate significantly during that period, in which case the exchange rates at the dates of the transactions are used. Exchange rate differences are recognized in other comprehensive income and accumulated in “Other reserves” within equity.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

Transactions in currencies other than the functional currency are recognized at the exchange rates prevailing at the dates of the transactions. Profit or loss on transactions in currencies other than the functional currency resulting from the settlement of such transactions and from the translation at year-end exchange rates of monetary assets and liabilities denominated in foreign currencies, are recognized in the consolidated statements of profit or loss, except those which are recorded in other comprehensive income and accumulated in equity such as cash flows hedging derivatives.

Cash and cash equivalents include cash-on-hand, deposits held on demand at financial entities and other short-term highly liquid investments with an original maturity of three months or less and which are subject to an insignificant risk of changes in value.

Financial assets

Initial classification

Arauco classifies its financial assets into the following categories: fair value through profit or loss and amortized cost.

The classification is based on the business model used to manage the assets and the characteristics of their contractual cash flows.

Management determines the classification of its financial assets at the time of their initial recognition.

(a) Financial assets at fair value through profit or loss: these instruments are initially measured at fair value. Net income and losses, including any income from interest or dividends, are registered in the profit or loss of the period. Financial assets are classified in the category of financial assets at fair value through profit or loss when they are maintained for negotiation or designated in their initial registration as assets at fair value through profit or loss. A financial asset can be classified in this category if it is acquired mainly for the purposes of being sold in the short-term. Gain or losses of assets held for negotiations are registered in the consolidated statements of profit or loss, and the related interest is registered independently as financial income. Derivatives are classified as acquired for negotiation also unless they are designated as hedging instruments.

(b) Assets measured at amortized cost: they are initially registered at the fair value of the transaction, adding or subtracting the transaction costs that are directly attributable to the issuance of the financial asset or financial liability. The financial asset is maintained within a business model, the objective of which is to maintain financial assets to obtain contractual cash flows and the contractual conditions of the asset give rise, on specified dates, to cash flows that are solely payments of principal and interest (“SPPI”) over the amount of the outstanding principal.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

Subsequent measurement

Financial instruments are subsequently measured at fair value through profit or loss or amortized cost.

The classification is based on two criteria: i) the Company’s business model for the management of financial instruments, and ii) whether the contractual cash flows related to the financial instruments represent “Solely Payments of Principal and Interest”.

a) Financial assets at fair value through profit or loss: these instruments are subsequently measured at fair value. Net earnings and losses, including income from interest and dividends, are registered as profits or losses for the period. These instruments are held for negotiation, and they are mainly acquired to be sold in the short-term. Derivatives are also classified as held for negotiation, unless they are registered as hedging instruments. Financial instruments of this type are classified as other current and non-current financial assets. They are subsequently valuated by determining their fair value, registering changes in value in the consolidated statements of profit or loss, in the items of financial income or financial costs.

b) Financial assets measured at amortized cost: These instruments are subsequently measured at amortized cost minus accumulated amortizations, using the effective interest method and adjusted by loss allowance and volume discounts, in the case of financial assets. Financial income and expenses, foreign exchange income and losses, and impairment are registered in results. Any earnings or losses due to initial or subsequent reductions of the value of the asset are registered in the statement of profit or loss of the period. Borrowings and receivables are non-derivative financial instruments with fixed or determinable payments not traded in any active market. They are registered at amortized cost, registering accrued conditions directly in profit or loss.

Arauco measures accumulated losses in a quantity equivalent to expected credit losses during the lifelong commitment. Expected credit losses are based on contractual cash flow differences based on the allowance of each contract and the cash flows that Arauco expects. The difference is then discounted based on an approximation of the asset’s original effective interest rate. The asset’s carrying value is reduced as the allowance is used, and the loss is recognized in sales expenses in the consolidated statements of profit or loss. When an account receivable cannot be collected, it is regularized against the allowance account for receivables. Subsequent recoveries of previously impaired amounts are recognized as a debit in distribution cost.

Derivative financial instruments are explained in Note 1 h).

Additionally, Arauco manages portfolio sales programs, which are accounted for in accordance with IFRS 9 on Financial Instruments. The assigned accounts receivable are derecognized only when Arauco has substantially transferred all the related risks and benefits incidental to their ownership.

To assess whether substantially all the risks and benefits of ownership have been transferred, Arauco considers, among other factors, credit risk, late payment risk, and foreign exchange risk. Collections related to the assigned portfolio of accounts receivable are presented in the consolidated statement of cash flows as part of operating activities.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

Financial liabilities

Arauco classifies its financial liabilities as follows: fair value through profit or loss, derivatives designated as effective hedging instruments and amortized costs.

Management determines the classification of its financial liabilities upon initial recognition. Financial liabilities are derecognized when the obligation is cancelled, settled or expired. When an existing financial liability is replaced with another of the same provider under substantially different terms, or where the terms of an existing liability are substantially amended, such exchange or modification is treated as a write-off of the original liability, with a new liability being recognized, and the difference between the respective carrying amounts is recognized in the consolidated statement of profit or loss.

Financial liabilities are initially recognized at fair value, and in the case of borrowings, they include the costs directly attributable to the transaction. The subsequent measurement of the financial liabilities depends on their classification:

Financial liabilities at fair value through profit or loss

Financial liabilities are included in the category of financial liabilities at fair value through profit or loss when they are held for trading or originally designated at fair value through profit or loss. Income and losses from liabilities held for trading are recognized in profit or loss. This category includes non-designated derivatives for hedging accounting.

Financial liabilities at amortized cost

Other financial liabilities are subsequently valued at their amortized cost based on the effective interest rate method. The amortized cost is calculated taking into account any premium or acquisition discount and includes the costs of transactions that are an integral part of the effective interest rate. This category includes commercial accounts payable and other accounts payable, lease liabilities, as well as the borrowings included in other current and non-current financial liabilities.

(i) Derivative financial instruments - The Company enters into a variety of derivative financial instruments to manage its exposure to interest rate and foreign exchange rate risks, including foreign exchange forward contracts, interest rate swaps, currency swaps and zero cost collar contracts. The Company’s policy is to enter into derivatives contracts only for economic hedging purposes and not with speculation objectives.

Derivatives are initially recognized at fair value at the date the derivative contracts are entered into and are subsequently re-measured at fair value at the end of each reporting period. The resulting gain or loss is recognized in profit or loss unless the derivative is designated as a hedging instrument and complies with hedge accounting requirements, in which event the timing of the recognition in profit or loss depends on the nature of the hedge relationship.

(ii) Embedded derivatives

The Company assesses the existence of embedded derivatives in financial instrument contracts. Derivatives embedded in non-derivative host contracts are treated as separate derivatives when they meet the definition of a derivative, their risks and characteristics are not closely related to those of the host contracts and the contracts are not measured at FVTPL as a whole. Arauco has determined that no embedded derivatives currently exist.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

(iii) Hedge accounting

The Company designates certain hedging instruments as either fair value hedges or cash flow hedges.

At the inception of the hedge relationship, the entity documents the relationship between the hedging instrument and the hedged item, along with its risk management objectives and its strategy for undertaking various hedge transactions. Furthermore, at the inception of the hedge and on an ongoing basis, Arauco documents whether the hedging instrument is highly effective in offsetting changes in fair values or cash flows of the hedged item attributable to the hedged risk.

-Fair value hedges

Changes in the fair value of derivatives that are designated and qualify as fair value hedges are recognized in profit or loss immediately, together with any changes in the fair value of the hedged asset or liability that are attributable to the hedged risk.

-Cash flow hedges

The effective portion of changes in the fair value of derivatives that are designated and qualify as cash flow hedges is recognized in other comprehensive income and accumulated under the heading of cash flow hedging reserve. The gain or loss relating to the ineffective portion is recognized immediately in profit or loss, and is included in the Finance costs line item in the consolidated statement of profit or loss. Amounts previously recognized in other comprehensive income are reclassified to profit or loss in the periods when the hedged item affects profit or loss, in the same line as the recognized hedged item.

Hedge accounting is discontinued when the Group revokes the hedging relationship, when the hedging instrument expires or is sold, terminated, or exercised, or when it no longer qualifies for hedge accounting. Any gain or loss recognized in other comprehensive income and accumulated in equity at that time remains in equity and is recognized when the forecasted transaction is ultimately recognized in profit or loss. When a forecasted transaction is no longer expected to occur, the gain or loss accumulated in equity is recognized immediately in profit or loss.

Inventories are measured at the lower of cost or net realizable value. Cost is determined using the weighted average cost method.

The cost of finished and in process products includes the cost of raw materials, direct labor, other direct costs and manufacturing overhead expenses.

Initial costs of harvested wood are determined at fair value less cost of sale at the point of harvest.

Biological assets are transferred to inventories when forests are harvested.

Net realizable value is the estimated selling price in the ordinary course of business less the estimated costs of completion and the estimated costs necessary to make the sale.

When market conditions result in the production costs of a product exceeding its net realizable value, the inventories are written-down to their net realizable value. This write-down also includes obsolescence amounts resulting from the terms and conditions of sale of the products, slow moving inventories and technical obsolescence.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

Spare parts that will be consumed in a period of less than twelve months are presented in inventories and recognized as an expense when they are consumed.

Arauco classifies certain property, plant and equipment, intangible assets, investments in associates and disposal groups (groups of assets to be sold together with their directly associated liabilities) as non-current assets held for sale which as of the date of the consolidated statements of financial position are the subject of active sale efforts which are estimated to be highly probable.

These assets or disposal groups are measured at the lower of the carrying amount or the fair value less the costs to sell, and are no longer depreciated or amortized from the time they are classified as non-current assets held for sale.

Arauco applies the acquisition method to account for a business combination. This method requires the identification of the acquirer, determination of the acquisition date, recognition and measurement of the identifiable assets acquired, the liabilities assumed and any non-controlling interest in the acquiree, and recognition and measurement of goodwill or a gain from a bargain purchase. Identifiable assets acquired and liabilities assumed and any contingent liabilities in a business combination are initially measured at fair value at the acquisition date, except:

-deferred tax assets or liabilities, and assets or liabilities related to employee benefit arrangements are recognized and measured in accordance with IAS 12 Income taxes and IAS 19 respectively;

-liabilities or equity instruments related to share-based payment arrangements of the acquiree or share-based payment arrangements of the Group entered into to replace share-based payment arrangements of the acquiree are measured in accordance with IFRS 3 at the acquisition date; and

-assets (or disposal groups) that are classified as held for sale in accordance with IFRS 5 Non-current assets held for sale and discontinued operations are measured in accordance with such standard.

Acquisition-related costs are accounted for as expenses when they are incurred, except for costs to issue debt or equity securities which are recognized in accordance with IAS 32 and IFRS 9.

A parent will present non-controlling interests in the consolidated statement of financial position within equity, separately from the equity of the owners of the parent company.

Changes in the ownership interest of a parent in its subsidiary that do not result in a loss of control are treated as equity transactions. Any difference between the amount by which non-controlling interests are adjusted and the fair value of the consideration paid or received is recognized directly in equity and attributed to owners of the parent company. No adjustment is made to the carrying amount of goodwill, neither gains nor losses are recognized in the statement of profit or loss.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

Non-controlling interests that are present ownership interests and entitle their holders to a proportionate share of the entity's net assets in the event of liquidation may initially be measured either at fair value or at the present ownership instruments' proportionate share of non-controlling interests, in the recognized amounts of the acquirer’s identifiable net assets. The choice is made on a transaction-by-transaction basis.

Arauco measures the fair value of the acquired company in the business combination achieved in each stage (“step acquisition”), recognizing the effects of remeasurement of previously held equity in the acquiree in the consolidated statements of profit or loss.

If the initial accounting for a business combination is not completed by the end of the reporting period in which the combination occurs, Arauco reports preliminary amounts for the items for which the accounting is incomplete. During the measurement period (no more than one year), these preliminary amounts are retrospectively adjusted, or additional assets or liabilities are recognized to reflect new information about facts and circumstances that existed at the acquisition date, if known, would have affected the amounts recognized at that date.

Business combinations that are under common control transactions are accounted using as a reference the pooling of interest. Under this method, assets and liabilities related to the transaction carry over the previous carrying values. Any difference between assets and liabilities included in the consolidation and the consideration transferred, is accounted in equity.

Associates are entities over which Arauco exercises significant influence, but not control. Significant influence is the power to participate in the financial and operating policy decisions of the investee but is not control or joint control over those policies.

Joint arrangement is defined as an entity over which there is joint control, which exists only when the decisions about strategic of activities, both financial and operational, require the unanimous consent of the parties sharing control.

Investments in joint arrangements are classified as a joint venture or as a joint operation. A joint operation is a joint arrangement in which the parties that have joint control of the arrangement (i.e. joint operators) have rights to the assets and obligations for the liabilities, relating to the arrangement. A joint venture is a joint arrangement in which the parties that have joint control of the arrangement (i.e., participants in a joint venture) have rights to the net assets of the arrangement.

Investments in associates and joint ventures are accounted for using the equity method and are initially recognized at cost. Their carrying amount is increased or decreased to recognize the portion corresponding to the statement of profit or loss or to the statement of comprehensive income. Dividends received are recognized by deducting the amount received from the carrying amount of the investment. Arauco’s investment in associates includes goodwill (both net of any accumulated impairment loss).

The investments in joint operations are recognized through consolidation of assets, liabilities and results of operations in relation to Arauco's ownership percentage.

If the acquisition cost is lower than the fair value of the net assets of the associate acquired, the difference is recognized directly in statement of profit or loss in line other gains (losses).

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

Investments in associates and joint ventures are presented in the interim consolidated statement of financial position in the line item “Investments accounted for using equity method”.

If Arauco’s share of losses of an associate or joint venture equals or exceeds its interest in the associate or joint venture, Arauco discontinues recognizing its share of further losses. After Arauco's carrying value in the investee is reduced to zero, additional losses are provided for, and a liability is recognized, only to the extent that Arauco has incurred legal or constructive obligations or made payments on behalf of the associate or joint venture. If the associate or joint venture subsequently reports profits, Arauco resumes recognizing its share of those profits only after its share of the profits equals the share of losses not recognized.

After initial recognition, intangible assets with finite useful lives are carried at cost less any accumulated amortization and impairment losses.

Amortization of an intangible asset with a finite useful life is allocated over the asset’s useful life. Amortization begins when the asset is available for use, i.e., when it is in the location and condition necessary for it to be capable of operating in the manner intended by management.

Computer software licenses are capitalized in terms of the costs incurred to acquire and make them compatible with existing software. These costs are amortized over the estimated useful lives of the software.

This item includes water rights, rights of way and other acquired rights recognized at historical cost which have indefinite useful lives as there is no foreseeable limit to the period over which these assets are expected to generate future cash flows. These rights are not amortized, but are tested for impairment at least annually, or when there is any indication that the assets might be impaired.

Correspond to the valuation over the time of the established relationship with customers, from the sale of products and services through its sales team. These relations will materialize in sales orders, which generate revenue and cost of sales. The useful life has been determined to be 15 years.

Goodwill is measured as the excess of the sum of the consideration transferred, the amount of any non-controlling interest in the acquired company, and the fair value of the acquirer's previously held equity interest in the acquired company (if any) over the net of the acquisition-date amounts of the identifiable assets acquired and the liabilities assumed. If the total of consideration transferred, non-controlling interest recognized and previously held interest measured is less than the fair value of the net assets of the subsidiary acquired in the case of a bargain purchase, the difference is recognized directly in the statements of profit or loss.

Goodwill is not amortized but tested for impairment on annual basis.

After initial recognition, goodwill is measured at cost less any accumulated impairment losses. For purposes of impairment testing, goodwill in a business combination is allocated as of the acquisition date to the cash generating unit or a group of cash generating units expected to benefit from the synergies of the combination irrespective of whether other assets or liabilities of the acquired company are allocated to those units or group of units.

The goodwill generated on acquisitions of foreign companies, is expressed in the functional currency of such foreign company.

Goodwill recognized in subsidiaries Arauco Canada Ltd. and Arauco do Brasil S.A., generated on subsidiaries acquisitions whose functional currency is different from the functional currency of the parent company and presentation of these consolidated financial statements, are translated into U.S. dollars at the closing exchange rate.

Property, plant and equipment are measured at cost less accumulated depreciation and accumulated impairment. The cost includes expenditures that are directly attributable to the acquisition of the assets.

Subsequent costs, such as improvements and replacement of components, are included in the asset’s carrying amount or recognized as a separate asset, as appropriate, only when it is probable that future economic benefits associated with the item will flow to Arauco and the cost of the item can be measured reliably. The carrying amount of the replaced part is derecognized from property, plant and equipment. All other repairs and maintenance costs are expensed in the period in which they are incurred.

Arauco capitalizes borrowing costs that are directly attributable to the acquisition, construction or production of qualifying assets as part of the cost of those assets, until the assets are ready for their intended use (See Note 12).

Depreciation is calculated by components using the straight-line method.

The useful lives of the items of property, plant and equipment is estimated according to the expected use of the assets. The residual values and useful lives of assets are reviewed and adjusted, if appropriate, annually.

Arauco applies IFRS 16 for recognizing leases in a manner consistent with contracts with similar features and akin circumstances.

At the beginning of a contract, Arauco assesses whether the contract is, or if it contains, a lease. A contract is, or contains, a lease if it transfers the right to control the use of a given asset for a certain period of time, in exchange for consideration.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

As of the initial date for recording a lease, Arauco, as lessee, recognizes an asset by the right of use at cost.

The cost of the asset for right of use comprises:

After the initial recognition date, Arauco, as lessee, recognizes its asset for right of use by applying the cost model, minus the accumulated depreciation and impairment losses, and adjusted for remeasurement of the liability for lease.

At the beginning, Arauco in the capacity of lessee, recognizes the lease liability at present value of the lease payments that have not been disbursed as of that date. Lease payments are discounted using the incremental interest rate for financial borrowings.

After the initial recognition date, Arauco, as lessee, recognizes a liability for leases by increasing the book value, so as to reflect the interest over the liability for lease, reducing the amount in order to reflect the payments for leases that have been performed and once again recognizing the book value, so as to reflect the remeasurement and also to reflect the essential fixed payments for leases that have been revised.

Arauco presents the assets by right of use in the consolidated statement of financial position and are further disclosed in Note 8. Likewise, lease liabilities are presented in the consolidated statement of financial position and further disclosed in Note 23.

Arauco as lessor classify, according to IFRS 16, its leases as operational or financial, as the case may be.

Income from operating leases in which Arauco is the lessor are recognized on a straight-line basis during the term of the lease. Initial direct costs are added to the book value of the underlying asset and are recognized as expenses during the term of the lease on the same basis as the lease income. Leased assets are included within the statement of financial position, in property, plant and equipment. Arauco did not make adjustments with respect to assets that maintains as a lessor, as a result of IFRS 16 adoption.

When assets are leased under a financial lease, the present value of lease payments are recognized as financial accounts receivable. The difference between the gross receivable and the present value of such amount, is recognized as financial return on capital.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

Arauco evaluates the economic nature of the contracts that grant the right to use certain assets, for the purposes of determining the existence of implied leases. In these cases, the Company separates, at the beginning of the contract and based on its relative reasonable values, payments and considerations associated with the lease, from the rest of the elements incorporated into the contract.

IAS 41 requires that biological assets, such as standing trees, are measured at fair value less cost to sell in the statement of financial position. Forestry plantations are accounted for at fair value less costs to sell, based on the presumption that fair values of these assets can be measured reliably.

The measurement of the fair value of the biological assets is determined using a discounted cash flow model. Our cash flow projections include significant judgments and assumptions relating to discount rates, estimated growth of the forests and sales margins. This valuation is performed on the basis of each identifiable farm block and for each type of tree.

Biological assets shown as current assets correspond to those forestry plantations that will be harvested in the short-term.

Biological growth and changes in fair value of forestry plantations are recognized in the line item “Other income” in the consolidated statements of profit or loss.

The tax liabilities are recognized in the interim consolidated financial statements based on the determination of taxable income for the year and calculated using the tax rates in force in the countries where Arauco operates.

Deferred income tax is recognized using liability method, on the temporary differences arising between the tax bases of assets and liabilities and their carrying amounts in the consolidated annual accounts. Deferred income tax is determined using tax rates contained in laws adopted as of the date of the financial statements and that are expected to be applicable when the related deferred tax asset is realized, or the deferred income tax liability is settled.

Deferred taxes are recognized in accordance with the standards established in IAS 12 - Income Tax.

The goodwill arising on business combinations does not give rise to deferred tax.

The deferred tax assets and tax credits are generally recognized for all deductible temporary differences to the extent that it is probable that future taxable profit will be available against which those deductible temporary differences can be utilized.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

Provisions are recognized when the Company has a present obligation, legal or constructive, as a result of past events, under which, it is probable that an outflow of resources will be required to settle the obligation; and when a reliable estimate can be made of the amount of the obligation. The amount recognized as a provision is the best estimate of the consideration required to settle the present obligation at the end of the reporting period.

Non-financial assets are recognized when it is probable that the related economic benefits will flow to the entity and their cost can be measured reliably.

Non-financial liabilities are recognized when a legal or constructive obligation exists as a result of a past event, it is probable that an outflow of economic resources will be required to settle the obligation, and the amount of the obligation can be measured reliably.

Revenues are valued at fair value of the consideration received or to be received, derived from them. Arauco analyses and takes under consideration all relevant facts and circumstances to apply the five-step model established under IFRS 15 to customer contracts: (i) identify the contract, (ii) identify the performance obligations, (iii) determine the transaction price, (iv) allocate the transaction price, and (v) recognize revenue. Additionally, Arauco evaluates the incremental costs of obtaining a contract and the costs incurred to comply with a contract. Arauco recognizes revenues when the steps established in IFRS have been satisfactorily complied with.

Accounts receivable are recognized when control over goods or services has been transferred to the customer, because at this point of the time collection is unconditional and the passage of time is only needed to receive payment.

Revenue from the sale of goods is recognized when Arauco has transferred to the buyer the significant risks and rewards of ownership of the committed goods, when the amount of revenue can be reliably measured, when Arauco does not retain any managerial involvement over the goods sold and when it is probable that the economic benefits associated with the transaction will flow to Arauco and the costs incurred in respect of the transaction can be measured reliably. Revenue from the sale of goods are recognized when there is no obligation unsatisfied that could affect the customer’s acceptance of the product. The delivery is effective when the products are sent to the specific location, the risks of obsolescence and loss have been transferred to the customer and when Arauco has objective evidence that all acceptance criteria have been satisfied.

Sales are recognized in terms of the price agreed to in the sales contract, less any volume discounts and estimated product returns at the date of the sale. There is no significant financing component given that receivables from sales are collected within a short period, which is in line with market practices.

The structure for recognizing revenue from export sales is based on the 2010 Incoterms, which are the official rules for the interpretation of commercial terms issued by the International Chamber of Commerce.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

The main Incoterms used by Arauco are the following:

“CFR (Cost and freight)”, where the company bears all costs including main transportation, until the products arrive at its port of destination. The risk is transferred to the purchaser once the products have been loaded onto the vessel, in the country of origin.

“CIF (Cost Insurance & Freight)”, where the Company organizes and pays for external freight services and some other expenses. Arauco is no longer responsible for the products once they have been delivered to the ocean carrier company.

Revenue from the rendering of services is recognized as long as the performance obligation has been satisfied.

Revenue is recognized considering the stage of completion of the transaction at the date of the reporting period, when Arauco has the enforceable right of payment from the rendering of the services.

There is no significant financing component, given that sales are made with a reduced average collection period, which is in line with market practice.

Arauco mainly provides power supply services which are transacted principally in the spot market of the Sistema Eléctrico Nacional (SEN) (“National Electrical System”). According to current regulations, the prices on that market called “Marginal Costs” are calculated by the Coordinador Eléctrico Nacional (CEN) (“National Electrical Coordinator”) and are generally recognized in the period in which the services are rendered.

Electrical power is generated as a by-product of the pulp and wood process and is a complementary business to it, which is initially supplied to the group’s subsidiaries and any surplus is sold to the SEN.

Arauco provides other non-core services such as port services and pest control whose revenues are derived from fixed price service contracts are recognized considering the stage of completion of the services rendered at the date of reporting, generally during the period of the service contract on a straight-line basis over the term of the contract.

Revenues from reportable segments mentioned in Note 24 are measured in accordance with the policies indicated in the preceding paragraphs.

Revenues from inter-segment sales (which are made at market prices) are eliminated in the interim consolidated financial statements.

The statutes of the Company provide that for the purposes of the annual distribution of the net income of each year, it will be up to the Ordinary Shareholders' Meeting annually to determine the part of said profits that will be distributed as a dividend to the shareholders. Such determination will be made by the Board without being subject to the minimum of 30% established in article No. 79 of the Chilean Corporations Law No. 18,046, on Public Limited Companies, and may agree to the distribution of a lower percentage.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

In a board meeting on September 24, 2024, it was agreed to modify the dividend policy, establishing that an amount equivalent to 30% of the distributable net profit for the fiscal years 2024, 2025 and 2026, will be distributed annually. For subsequent years, an amount equivalent to 40% of the distributable net income for each fiscal year will be distributed as dividends. Nevertheless, the Board of Directors may decide to distribute and pay dividends to the shareholders, to the extent that it expects the year to finalize with positive results and that the Company’s liquidity allows such distribution and payment.

At the board meeting held on October 24, 2025, an amendment to the dividend policy was approved, establishing that if the Company exercises its option to defer the payment of interest on the Series “AG” Bonds, issued and placed in the local market on the same date, the Company may not declare or pay dividends while any deferred interest remains outstanding.

Basic earnings per share are calculated by dividing the net profit for the period attributable to owners of the parent company by the weighted average number of ordinary shares outstanding during the period, excluding the average number of shares in the Company held by a subsidiary, if such circumstance exists. Arauco has not performed any type of transaction with a potential dilutive effect that would cause diluted earnings per share to be different from basic earnings per share.

Non-financial assets

The recoverable amount of property, plant and equipment and other long-term assets with finite useful lives are measured whenever there are any circumstances indicating that the assets have to recognize an impairment loss. Among the circumstances to consider as evidence of impairment are significant declines in the assets’ market value, significant adverse changes in the technological environment, obsolescence or physical damages of assets and changes in the manner in which the asset is used or expected to be used). Arauco evaluates at the end of each reporting period whether there is any evidence of the indications above mentioned.

A previously recognized impairment loss is reversed if there has been a change in the estimates used to determine the recoverable amount however a reversal of an impairment loss shall not exceed the carrying amount that would have been determined (net of amortization or depreciation) had no impairment loss been recognized for the asset in prior years.

For the purposes of assessing impairment losses, assets are grouped at the lowest level for which there is identifiable cash flows separately for each cash-generating unit. Non-financial assets, other than goodwill, which had recognized an impairment loss, are reviewed at the end of each reporting period whether there are any circumstances indicating that an impairment loss previously recognized may no longer exist or has decreased.

“Cash-generating units” are the smallest identifiable groups of those cash inflows that are largely independent of the cash inflow from other assets or groups of assets.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

Goodwill

Goodwill and intangible assets with indefinite useful life are tested annually for impairment or whenever circumstances indicate it. The recoverable amount of an intangible asset is the higher of its fair value less costs to sell and its value in use. An impairment loss is recognized whenever the carrying amount exceeds the recoverable amount.

A cash-generating unit, for which goodwill has been allocated, is tested for impairment annually or more frequently when there are circumstances indicating that the unit may be impaired. If the recoverable amount of the cash-generating unit is less than its carrying amount, the impairment loss is allocated first to reduce the carrying amount of any goodwill allocated to the unit and then to other assets pro rata based on the carrying amount of each asset in the unit. Any impairment loss of goodwill is recognized directly in the consolidated statement of profit or loss. An impairment loss recognized for goodwill is not reversed in subsequent periods.

Goodwill is allocated to cash-generating units for impairment testing purposes. The allocation is made between cash-generating units or groups of cash generating units expected to benefit from the synergies of the combination.

Financial assets

At the end of each reporting period, an assessment is performed in order to identify whether there is any objective evidence that a financial asset or a group of financial assets may have been impaired.

An allowance for doubtful accounts is established based on a measurement of expected losses using a simplified approach.

The allowance for doubtful accounts is measured as the difference between the carrying amount of receivables and the present value of estimated future cash flows. The carrying amount of the receivable is reduced through the use of the allowance. If the impairment loss decreases in later periods, it is reversed either directly or by adjusting the provision for doubtful accounts, with effect in profit or loss.

Arauco constitutes labor obligations for severance payable in all circumstances for certain of its employees with at least 5 years of work in the Company, based on the terms of the staff’s collective and individual bargaining agreements.

The related provision is an estimate of the years of service to be recognized as a future labor obligation liability, in accordance with contracts between Arauco and its employees and pursuant to actuarial valuation criteria for this type of liability. This post-employment benefit is considered a defined benefit plan.

The main factors considered for calculating the actuarial value of severance obligation for years of service are employee turnover, salary increases and life expectancy of the workers included in this benefit.

Actuarial gains and losses are recognized in other comprehensive income in the year they are incurred.

These obligations are related to post-employee benefits in accordance with current standards.

Arauco recognizes the expense for employee vacation according to labor legislation in each country on an accrual basis.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

This obligation is presented in line item “Trade and other current payables” in the consolidated statements of financial position.

a) Standards, interpretations and amendments that are mandatory for the first time for annual periods beginning on January 1, 2026:

The adoption of the amendments described in the table above have not had a significant impact on Arauco’s interim consolidated financial statements.

b) Standards, interpretations and amendments, the application of which is not yet mandatory, which have not been adopted in advance:

Arauco estimates that the adoption of the standards, amendments and interpretations described in the table above will not have a significant impact on Arauco’s interim consolidated financial statements during its initial application period, except for the new IFRS 18 standard that will modify the actual presentation of the Income Statement, and we are currently evaluating any significant impacts.

 CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

NOTE 2. ACCOUNTING POLICIES, CHANGES IN ACCOUNTING ESTIMATES

Changes to accounting policies

As of March 31, 2026, there had not been significant changes in the accounting policies with respect to the 2025 financial year.

Changes to accounting estimates

As of March 31, 2026, there had been no changes in the methodologies for calculating the accounting estimates with respect to the 2025 financial year.

NOTE 3. DISCLOSURE OF OTHER INFORMATION

As of March 31, 2026 and December 31, 2025, the shareholders composition according to the amount of shares owned was as follows:

At the date of these interim consolidated financial statements, the share capital of Arauco was ThU.S.$ 1,553,618.

On May 7, 2025, a definitive dividend of ThU.S.$ 112,287 was paid in accordance with the dividend policy for the distribution of 30% of the distributable net profit, after deducting the payment made in December 2024 of ThU.S.$ 94,397.

As of March 31, 2026 and 2025, no provision for minimum dividends has been recognized, as distributable net income resulted in a loss in both periods.

See Note 26 for details.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

Other reserves comprise reserves of exchange differences on translation, reserves of cash flow hedges and other reserves. Arauco does not have any restrictions associated with these reserves.

Reserves of exchange differences on translation

Reserves of exchange differences on translation correspond to exchange differences of Arauco’s subsidiaries whose functional currency is other than Arauco’s presentation currency.

Reserves of cash flow hedges

The hedging reserve corresponds to the part of the net gains or losses of derivatives financial instruments that qualify as cash flow hedges, in force in Arauco at the end of each period/fiscal year.

Reserve of actuarial losses in defined benefit plans

This corresponds to changes in the present value of the obligation for defined benefits resulting from experience adjustments (the effect of the differences between the previous actuarial assumptions and the events that occurred within the context of the plan) and the effects of the changes in the actuarial assumptions.

Other reserves

This mainly corresponds to the share of legal reserves and other comprehensive income of investments in associates and joint agreements.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

The table below sets forth other income, other expenses, finance income, finance costs and share of profit (loss) of associates and joint ventures for the year ended March 31, 2026 and 2025 are as follows:

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

The analysis of expenses by nature contained in these consolidated financial statements is presented below:

Total amount is comprised of the cost of inventory sales for ThU.S.$ 1,134,186 for the period ended March 31, 2026 (ThU.S.$ 1,075,944 for the period ended March 31, 2025) and the cost of rendering services for ThU.S.$ 25,747 for the period ended March 31, 2026 (ThU.S.$ 28,845 for the period ended March 31, 2025).

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

NOTE 4. INVENTORIES

Inventories are subject to adjustments for obsolescence and are evaluated to ensure they are recorded at the lower between cost and net realizable value. As of March 31, 2026, inventories increased by ThU.S.$ 4,086 (reduced by ThU.S.$ 5,457 as of December 31, 2025) as a result of write-downs to net realizable value. Such write-downs were recognized in cost of sales in both periods.

As of March 31, 2026, the amount of obsolescence provision and net realizable value is ThU.S.$ 76,647 (ThU.S.$ 84,217 as of December 31, 2025), as a consequence of the foregoing, a net increase of inventories was recognized of ThU.S.$ 7,570 (higher provision of ThU.S.$ 2,349 as of March 31, 2025).

For the period ended March 31, 2026, there were inventory write-offs of ThU.S.$ 234 (ThU.S.$ 1,225 for the period ended March 31, 2025), which are presented in the consolidated statements of profit or loss within cost of sales.

As of the date of these consolidated financial statements, no inventories were pledged as security.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated

NOTE 5. CASH AND CASH EQUIVALENTS

Cash and cash equivalents include cash on hand, bank checking account balances, time deposits and mutual funds. These are short-term highly liquid investments that are readily convertible to known amounts of cash and are subject to an insignificant risk of changes in value.

The investment objective of time deposits is to maximize the amounts of cash surpluses in the short-term. These instruments are permitted under Arauco’s Investment Policy which allows investing in fixed income securities. These instruments have a maturity of less than three months from the date of acquisition.

Arauco invests in local and international mutual funds in order to maximize the returns of cash surpluses denominated in Chilean pesos or in foreign currencies such as U.S. dollars or Euros. These instruments are permitted under Arauco’s Investment Policy.

As of the date of these consolidated financial statements, there are no amounts of cash and cash equivalents with restrictions on use.

The risk classification of the Company’s mutual funds as of March 31, 2026 and December 31, 2025 is shown below.

(*) Correspond to mutual funds whose local classification applies a methodology different from that used for the other mutual funds in which the Company invests. Nevertheless, these funds meet the definition of cash equivalents, as they are subject to an insignificant risk of changes in value.

Changes in financial liabilities

(*) Includes interest capitalized to the debt during the period amounting to ThU.S.$ 5,135.

CELULOSA ARAUCO Y CONSTITUCION S.A. AND SUBSIDIARIES

Unaudited consolidated financial statements

March 31, 2026

Amounts in thousands of U.S. dollars, except as indicated