Exhibit 99.1

GERDAU S.A.

Condensed consolidated interim financial statements

as of March 31, 2026

GERDAU S.A.

CONSOLIDATED BALANCE SHEETS

In thousands of Brazilian reais (R$)

(Unaudited)

The accompanying notes are an integral part of these Condensed Consolidated Interim Financial Statements

GERDAU S.A.

CONSOLIDATED BALANCE SHEETS

In thousands of Brazilian reais (R$)

(Unaudited)

The accompanying notes are an integral part of these Condensed Consolidated Interim Financial Statements

GERDAU S.A.

CONSOLIDATED STATEMENTS OF INCOME

In thousands of Brazilian reais (R$)
(Unaudited)

The accompanying notes are an integral part of these Condensed Consolidated Interim Financial Statements

GERDAU S.A.

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME

In thousands of Brazilian reais (R$)

(Unaudited)

The accompanying notes are an integral part of these Condensed Consolidated Interim Financial Statements

GERDAU S.A.

CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY

in thousands of Brazilian reais (R$)
(Unaudited)

The accompanying notes are an integral part of these Condensed Consolidated Interim Financial Statements

GERDAU S.A.

CONSOLIDATED STATEMENTS OF CASH FLOWS

In thousands of Brazilian reais (R$)

(Unaudited)

The accompanying notes are an integral part of these Condensed Consolidated Interim Financial Statements

GERDAU S.A.

NOTES TO THE CONDENSED CONSOLIDATED INTERIM FINANCIAL STATEMENTS

as of March 31, 2026

(In thousands of Brazilian Reais – R$, unless otherwise stated)

(Unaudited)

NOTE 1 - GENERAL INFORMATION

Gerdau S.A. is a publicly traded corporation (sociedade anônima) with its corporate domicile in the city of São Paulo, Brazil. Gerdau S.A and subsidiaries (collectively referred to as the “Company”) is a leading producer of long steel in the Americas and one of the largest suppliers of special steel in the world. In Brazil, the Company also produces flat steel and iron ore, activities which expanded the product mix and made its operations even more competitive. The Company believes it is the largest recycler in Latin America and around the world it transforms each year millions of tons of scrap into steel, reinforcing its commitment to sustainable development of the regions where it operates. Gerdau is listed on the São Paulo and New York stock exchanges.

The Condensed Consolidated Interim Financial Statements of the Company were approved by the Management on April 27, 2026.

NOTE 2 - SUMMARY OF SIGNIFICANT ACCOUNTING PRACTICES

2.1 - Basis of Presentation

The Company's Condensed Consolidated Interim Financial Statements for the three-month period ended on March 31, 2026 have been prepared in accordance with International Accounting Standard (IAS) Nº 34, which establishes the content of condensed interim financial statements. These Condensed Consolidated Interim Financial Statements should be read in conjunction with the Consolidated Financial Statements of Gerdau S.A., as of December 31, 2025, which were prepared in accordance with International Financial Reporting Standards (IFRS) as issued by the International Accounting Standards Board - IASB.

The preparation of the Condensed Consolidated Interim Financial Statements in accordance with IAS 34 requires Management to make accounting estimates. The Condensed Consolidated Interim Financial Statements have been prepared using the historical cost as its basis, except for the valuation of certain financial instruments, which are measured at fair value.

The accounting policies applied in this Condensed Consolidated Interim Financial Statements are the same as those applied in the Consolidated Financial Statements for the year ended December 31, 2025.

2.2 – New accounting standards

The issued and/or reviewed IFRS standards made by the IASB that are effective for the year started in 2026 had no impact on the Company's Financial Statements. In addition, the IASB issued/reviewed some IFRS standards, which have mandatory adoption for the year 2027 and/or after, and the Company is assessing the adoption impact of these standards in its Consolidated Financial Statements.

- Issuance of IFRS 18 – Presentation and Disclosure in Financial Statements. It will replace IAS 1 – Presentation of Financial Statements, introducing new requirements that will help achieve comparability of the financial performance of similar entities and provide more relevant information and transparency to users. Although IFRS 18 does not impact the recognition or measurement of items in financial statements, its impacts on presentation and disclosure are expected to be widespread, in particular those related to the demonstration of financial performance and the provision of performance measures defined by management within the financial statements. This standard is effective for years beginning on/or after January 1, 2027. The Company is evaluating the impacts on its Financial Statements of adopting this standard.

- Issuance of IFRS 19 – Subsidiaries without Public Accountability: Disclosures. Establishes simplified disclosures requirements for consolidated or individual financial statements of entities eligible for the application of this standard. These rules are effective for fiscal years beginning on/or after January 1, 2027. The Company does not expect material impacts on its Financial Statements.

- Amendment to IFRS 19 - Subsidiaries without Public Accountability: Disclosures. Amends disclosure requirements originally provided for this standard. This amendment to the standards is effective for years beginning on/or after January 1, 2027. The Company does not expect material impacts on its Financial Statements.

GERDAU S.A.

NOTES TO THE CONDENSED CONSOLIDATED INTERIM FINANCIAL STATEMENTS

as of March 31, 2026

(In thousands of Brazilian Reais – R$, unless otherwise stated)

(Unaudited)

- Amendment to IAS 21 – Translation to a Hyperinflationary Presentation Currency. Changes treatment and disclosure requirements originally set forth in this standard. This amendment is effective for fiscal years beginning on or after January 1, 2027. The Company does not expect significant impacts on its Financial Statements.

- Amendment to the Illustrative Examples of IFRS 7, IFRS 18, IAS 1, IAS 8, IAS 36 and IAS 37 – Disclosures about Uncertainties in the Financial Statements. Changes disclosure requirements originally set forth in these standards. This amendment is effective for fiscal years beginning on or after January 1, 2027. The Company does not expect significant impacts on its Financial Statements.

NOTE 3 – CONDENSED CONSOLIDATED INTERIM FINANCIAL STATEMENTS

3.1 - Subsidiaries

The Company did not have material changes of interest in subsidiaries for the period ended on March 31, 2026, when compared to those existing on December 31, 2025.

3.2 - Joint Ventures

Listed below are the interests in joint ventures:

(*) The voting capital is substantially equal to the total capital. The interests reported represent the ownership percentage held directly and indirectly held in the joint venture.

Although the Company owns more than 50% of Gerdau Corsa S.A.P.I. de C.V., it does not consolidate the financial statements of this joint venture entity, due to joint control agreements with the other shareholders that prevent the Company from controlling the decisions in conducting the joint venture’s business. The Company owns 1.32% of MRS Logística S.A. and due to the existence of a shareholders' agreement, a joint venture business and the existence of significant influence provided for in the accounting standard for the application of the equity method is characterized.

The Company presents the joint venture information in aggregate, since the investments in these entities are not individually material. The financial information of these joint ventures, accounted for under the equity method, is shown below:

GERDAU S.A.

NOTES TO THE CONDENSED CONSOLIDATED INTERIM FINANCIAL STATEMENTS

as of March 31, 2026

(In thousands of Brazilian Reais – R$, unless otherwise stated)

(Unaudited)

3.3 — Associate companies

Listed below is the interest in associate companies:

(*) The voting capital is substantially equal to the total capital. The interests reported represent the ownership percentage held directly and indirectly.

The Company does not consolidate the Financial Statements of Dona Francisca Energética S.A. despite holding more than 50% of the total capital of this affiliate, due to protection rights granted to other shareholders that prevent the Company from fully implementing decisions regarding the conduct of the affiliate’s business.

The summarized financial information of the associate companies, accounted for under the equity method, is shown as follows:

GERDAU S.A.

NOTES TO THE CONDENSED CONSOLIDATED INTERIM FINANCIAL STATEMENTS

as of March 31, 2026

(In thousands of Brazilian Reais – R$, unless otherwise stated)

(Unaudited)

NOTE 4 – CASH AND CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS

Cash and cash equivalents

Immediately available investments include investments with maturity of up to 90 days or readily redeemable, that means, those that have immediate liquidity and low risk of fair value variation.

Short-term investments

Short-term investments include securities held for immediate trading or available for future sale and substantially include amounts in investment funds, whose portfolio is composed of Bank Deposit Certificates, government bonds, financial bills and debentures, among others, which are used to manage the cash from the Company’s operating activities and recorded at fair value. Income generated by these investments is recorded as financial income.

NOTE 5 – ACCOUNTS RECEIVABLE

GERDAU S.A.

NOTES TO THE CONDENSED CONSOLIDATED INTERIM FINANCIAL STATEMENTS

as of March 31, 2026

(In thousands of Brazilian Reais – R$, unless otherwise stated)

(Unaudited)

Accounts receivable by aging are as follows:

NOTE 6 - INVENTORIES

The allowance for adjustment to net realizable value of inventories, on which the provision and reversal of provision are registered with impact on cost of sales, is as follows:

NOTE 7 – INCOME AND SOCIAL CONTRIBUTION TAXES

In Brazil, income taxes include federal income tax (IR) and social contribution (CS), which represents an additional federal income tax. The statutory rates for income tax and social contribution are 25% and 9%, respectively, and are applicable for the periods ended on March 31, 2026 and 2025. The foreign subsidiaries of the Company are subject to taxation at rates ranging between 23% and 35%. The differences between the Brazilian tax rates and the rates of other countries are presented under “Difference in tax rates in foreign companies” in the reconciliation of income tax and social contribution below. The uncertain tax positions related to corporate income tax (IR) and social contribution (CS) are disclosed in Note 15.

GERDAU S.A.

NOTES TO THE CONDENSED CONSOLIDATED INTERIM FINANCIAL STATEMENTS

as of March 31, 2026

(In thousands of Brazilian Reais – R$, unless otherwise stated)

(Unaudited)

a) Reconciliations of income and social contribution taxes at statutory rates to amounts presented in the Statement of Income are as follows:

b) Tax assets not recognized:

Due to the lack of expectation to use tax losses, negative social contribution base and deferred exchange variation arising from some operations in Brazil, the Company did not recognize a portion of tax assets of R$ 1,032,869 (R$ 907,295 on December 31, 2025), which do not have an expiration date. The subsidiaries abroad had R$ 657,905 (R$ 701,413 as of December 31, 2025) of tax credits on capital losses for which deferred tax assets have not been recognized and which expire between 2027 and 2032 and also several Unrecognized tax loss carryforwards from state credits in the United States in the amount of R$ 255,803 (R$ 291,979 as of December 31, 2025), which expire at various dates between 2031 and 2038.

NOTE 8 – INVESTMENTS

NOTE 9 – PROPERTY, PLANT AND EQUIPMENT

a) Summary of changes in property, plant and equipment – during the three-month period ended on March 31, 2026, acquisitions amounted to R$ 1,097,665 (R$ 1,376,736 as of March 31, 2025), and disposals amounted to R$ 9,532 (R$ 13,394 as of March 31, 2025).

The additions to property, plant and equipment in the three-month period ended on March 31, 2026 include a non-cash effect amounted to R$ 70,310 (R$ 461,984 as of March 31, 2025).

GERDAU S.A.

NOTES TO THE CONDENSED CONSOLIDATED INTERIM FINANCIAL STATEMENTS

as of March 31, 2026

(In thousands of Brazilian Reais – R$, unless otherwise stated)

(Unaudited)

b) Capitalized borrowing costs – borrowing costs capitalized during the three-month period ended on March 31, 2026 amounted to R$ 45,171 (R$ 30,919 as of March 31, 2025).

c) Guarantees – no property, plant and equipment were pledged as collateral for loans and financing on March 31, 2026 and December 31, 2025.

NOTE 10 – GOODWILL

The changes in goodwill are as follows:

The amounts of goodwill by segment are as follows:

As of March 31, 2026 and December 31, 2025, the goodwill balances of R$ 11,376,317 and R$ 11,995,727, respectively, are allocated to the North American segment.

NOTE 11 – TRADE ACCOUNTS PAYABLE (domestic market, debtor risk and imports)

Under “Trade Accounts Payable - Domestic Market”, the Company presents balances payable arising from the acquisition of goods and services in the domestic markets of each of the countries where the Company and its subsidiaries operate.

The Company has contracts with financial institutions in order to allow its suppliers to anticipate their receivables through an operation called “Trade Accounts Payable – Debtor Risk”. In this operation, suppliers can transfer, at their discretion, the right to receive the securities to a financial institution, which, in turn, becomes the holder of the rights of the suppliers’ receivables. The average discount rate on risk transactions carried out by our suppliers with financial institutions in Brazil and with subsidiaries in the United States was based on market conditions. The transfer of the right to receive the Company’s securities, at the supplier’s discretion, does not change the payment term, nor does it imply the payment of interest by the Company, as the financial cost of such transfer is the responsibility of the supplier. Therefore, the payment term for suppliers at risk drawn varies between 7 and 132 days, with the same payment term for suppliers who do not choose to advance their receivables through the operation called “Trade Accounts Payable – Debtor Risk”.

GERDAU S.A.

NOTES TO THE CONDENSED CONSOLIDATED INTERIM FINANCIAL STATEMENTS

as of March 31, 2026

(In thousands of Brazilian Reais – R$, unless otherwise stated)

(Unaudited)

The amounts of liabilities under the supplier financing arrangement are considered to be reasonable approximations of their fair values, due to their short-term nature.

The balances presented as “Trade Accounts Payable - Imports” substantially refer to the purchase of coal and other raw materials abroad, where in commercial transactions the supplier may require the issuance of a letter of credit or similar risk mitigation instrument to ship the products. On March 31, 2026 and December 31, 2025, contracts negotiated via letter of credit had a payment term of up to 180 days and rates that also varied, depending on market conditions.

The Company permanently monitors the composition of the portfolio and the conditions established with suppliers, which have not undergone significant changes in relation to what had been practiced historically.

NOTE 12 – LOANS AND FINANCING

Loans and financing are as follows:

As of March 31, 2026, the nominal weighted average cost of debts denominated in US dollars is 6.12% p.a. (6.12% p.a. on December 31, 2025), for debts denominated in Real of CDI -2.06% p.a. (CDI -2.11% p.a. on December 31, 2025) and for other currencies 3.69% p.a. (3.64% p.a. on December 31, 2025).

Loans and financing, denominated in Reais, are substantially adjusted at a fixed rate or indexed to the CDI (Interbank Deposit Certificates).

Summary of loans and financing by currency:

The amortization schedules of long-term loans and financing are as follows:

GERDAU S.A.

NOTES TO THE CONDENSED CONSOLIDATED INTERIM FINANCIAL STATEMENTS

as of March 31, 2026

(In thousands of Brazilian Reais – R$, unless otherwise stated)

(Unaudited)

(*) On March 31, 2026, the amounts represents dates from April 1, 2027 to December 31, 2027.

a) Credit Lines

In September 2022, the Company completed the renewal of the Global Credit Line in the total amount of US$ 875 million (equivalent to R$ 4,567 million as of March 31, 2026) with maturity in September 2027. The transaction aims to provide liquidity to operations in North America and Latin America, including Brazil. The companies Gerdau S.A., Gerdau Açominas S.A. and Gerdau Aços Longos S.A. provide guarantee for this transaction. As of March 31, 2026, no amount of this credit line was used.

The Company and its subsidiaries are not subject to default clauses (covenants) linked to financial ratios. Non-financial performance clauses have been complied with.

b) Main amortization

In February 2026, the subsidiaries Gerdau Açominas S.A. and Gerdau Aços Longos S.A. fully settled debts contracted with a top-tier institution in the total amount of R$ 300 million, plus approximately R$ 18.6 million in interest.

NOTE 13 – DEBENTURES

Maturities of long-term amounts are as follows:

The debentures are denominated in Brazilian Reais, nonconvertible, and pay variable interest as a percentage of the CDI – Interbank Deposit Certificate. The Company and its subsidiaries are not subject to default clauses (covenants) linked to financial indexes.

The average interest rate was CDI + 0.58% for the year ended on March 31, 2026 (CDI + 0.62% for the year ended on March 31, 2025).

GERDAU S.A.

NOTES TO THE CONDENSED CONSOLIDATED INTERIM FINANCIAL STATEMENTS

as of March 31, 2026

(In thousands of Brazilian Reais – R$, unless otherwise stated)

(Unaudited)

NOTE 14 - FINANCIAL INSTRUMENTS

a) General considerations - Gerdau S.A. and its subsidiaries enter into transactions with financial instruments whose risks are managed through market strategies discussed and shared with senior management and in accordance with internal guidelines and control systems for exposure limits to them. All financial instruments are recorded in the accounting books and presented as short-term investments, trade accounts receivable, related parties (assets and liabilities), fair value of derivatives (assets and liabilities), other current assets, other non-current assets, trade accounts payable – domestic market, trade accounts payable – debtor risk, trade accounts payable - imports, loans and financing, debentures, other current liabilities and other non-current liabilities.

The Company has derivatives and non-derivative instruments, such as the hedge for some operations under hedge accounting. These operations are intended to protect the Company against exchange rate fluctuations on foreign currency loans, interest rate and commodity prices fluctuations. These transactions are carried out considering direct active or passive exposures, without leverage.

b) Fair Value — the Fair Value of the financial instruments is as follows:

The fair values of Loans and Financing and Debentures are based on market premises, which may take into consideration discounted cash flows using equivalent market rates and credit rating. All other financial instruments, which are recognized in the Consolidated Financial Statements at their carrying amount, are substantially similar to those that would be obtained if they were traded in the market. However, because there is no active market for these instruments, differences could exist if they were settled in advance. The fair value hierarchy of the financial instruments above is presented in Note 14.g.

c) Risk factors that could affect the Company’s and its subsidiaries’ businesses:

Price risk of commodities: this risk is related to the possibility of changes in prices of the products sold by the Company or in prices of raw materials and other inputs used in the productive process. Since the Company operates in a commodity market, net sales and cost of sales may be affected by changes in the international prices of their products or materials. In order to minimize this risk, the Company constantly monitors the price variations in the domestic and international markets. Furthermore, the Company may contract derivatives in order to reduce this risk.

Interest rate risk: this risk arises from the effects of fluctuations in interest rates applied to the Company’s financial liabilities or assets and future cash flows and income. The Company evaluates its exposure to these risks: (i) comparing financial assets and liabilities denominated at fixed and floating interest rates and (ii) monitoring the variations of interest rates like Secured Overnight Financing Rate (SOFR) and CDI. Accordingly, the Company may enter into interest rate swaps in order to reduce this risk.

GERDAU S.A.

NOTES TO THE CONDENSED CONSOLIDATED INTERIM FINANCIAL STATEMENTS

as of March 31, 2026

(In thousands of Brazilian Reais – R$, unless otherwise stated)

(Unaudited)

Exchange rate risk: this risk is related to the possibility of fluctuations in exchange rates affecting the amounts of financial assets or liabilities or of future cash flows and income. The Company assesses its exposure to the exchange rate by measuring the difference between the amount of its assets and liabilities in foreign currency. The Company understands that the accounts receivables originated from exports, its cash and cash equivalents denominated in foreign currencies and its investments abroad are more than equivalent to its liabilities denominated in foreign currency. Since the management of these exposures occurs at each operation level, if there is a mismatch between assets and liabilities denominated in foreign currency, the Company may contract derivative financial instruments in order to mitigate the effect of exchange rate fluctuations.

Credit risk: this risk arises from the possibility of the Company not receiving amounts arising from sales to customers or investments made with financial institutions. In order to minimize this risk, the Company adopt the procedure of analyzing in details of the financial position of their customers, establishing a credit limit and constantly monitoring their balances. Regarding financial investments, the Company only carries out transactions with first-rate institutions and with low credit risk, as assessed by rating agencies and risk mitigation parameters defined in the Company’s internal guidelines.

Capital management risk: this risk comes from the Company’s choice in adopting a financing structure for its operations. The Company manages its capital structure, which consists of a ratio between the financial debts and its own capital (Net Equity) based on internal policies and benchmarks. The Key Performance Indicators (KPI) related to the “Capital Structure Management” objective are: WACC (Weighted Average Cost of Capital), Net Debt/EBITDA (Earnings before interest, income tax, depreciation and amortization), Coverage Ratio of Net Financial Expenses (EBITDA/Net Financial Expenses) and Debt/Total Capitalization Ratio. Net Debt is formed by the principal of the debt reduced by cash, cash equivalents and short-term investments (notes 4, 12 and 13). Total Capitalization is formed by the Total Debt (composed of the principal of the debt) and the Net Equity (Note 17). The Company may change its capital structure, according to economic and financial conditions, in order to optimize its financial leverage and debt management. At the same time, the Company seeks to improve its ROCE (Return on Capital Employed) through the implementation of working capital management and an efficient program of investments in property, plant and equipment. In the long term, the Company seeks to remain within the parameters below, admitting occasional variations in the short term:

These key indicators are used to monitor objectives described above and may not necessarily be used as indicators for other purposes, such as impairment tests.

Liquidity risk: The Company’s management policy of indebtedness and cash on hand is based on using the committed lines and the currently available credit lines with or without a guarantee in export receivables for maintaining adequate levels of short, medium, and long-term liquidity. The maturity of long-term loans and financing, and debentures are presented in Notes 12 and 13, respectively.

GERDAU S.A.

NOTES TO THE CONDENSED CONSOLIDATED INTERIM FINANCIAL STATEMENTS

as of March 31, 2026

(In thousands of Brazilian Reais – R$, unless otherwise stated)

(Unaudited)

Sensitivity analysis:

The Company performed a sensitivity analysis, which can be summarized as follows:

Foreign currency sensitivity analysis: As of March 31, 2026, the Company is mainly exposed to variations between the Real and the Dollar. The sensitivity analysis carried out by the Company considers the effects of a 5% increase or decrease between the Real and the Dollar in its non-hedged debts (loans and financing), trade accounts receivable - exports from Brazil and trade accounts payable – imports (imports/exports). Variations between the local currencies of other countries and the Dollar do not represent material exposures. In this analysis, if the Real appreciates against the Dollar, this would represent a gain of R$ 4,974 (gain of R$ 10,821 as of March 31, 2025). If the Real depreciates against the Dollar, this would represent a loss of the same amount. As for foreign currency variations in Imports/Exports, if the Real appreciates against the Dollar, this would represent a loss of R$ 40,140 (loss of R$ 37,587 as of March 31, 2025), if the Real depreciates against the Dollar, this would represent a gain of the same value.

The net values of other assets and other liabilities in foreign currencies do not present significant risks of impacts due to fluctuations in the exchange rate.

Interest rate sensitivity analysis: The interest rate sensitivity analysis made by the Company considers the effects of an increase or reduction of 10 basis point (bps) on the average interest rate applicable to the floating part of its debt. The calculated impact, considering this variation in the interest rate totals R$ 38,648 as of March 31, 2026 (R$ 37,312 as of March 31, 2025) and would impact the Financial expenses account in the Consolidated Statements of Income. The specific interest rates to which the Company is exposed are related to the loans, financing, and debentures presented in Notes 12 and 13, and are mainly comprised by SOFR and CDI — Interbank Deposit Certificate.

GERDAU S.A.

NOTES TO THE CONDENSED CONSOLIDATED INTERIM FINANCIAL STATEMENTS

as of March 31, 2026

(In thousands of Brazilian Reais – R$, unless otherwise stated)

(Unaudited)

Sensitivity analysis of changes in sales price of products and price of raw materials and other inputs used in production: The Company is exposed to changes in the price of its products. This exposure is associated with the fluctuation of the sales price of the Company’s products and the price of raw materials and other inputs used in the production process, mainly for operating in a commodity market. The sensitivity analysis made by the Company considers the effects of an increase or of a reduction of 1% on both prices. The impact measured considering this variation in the price of products sold, considering the revenues and costs for the period ended on March 31, 2026, totals R$ 167,157 (R$ 173,753 as of March 31, 2025) and the variation in the price of raw materials and other inputs totals R$ 101,289 as of March 31, 2026 (R$ 111,417 as of March 31, 2025). The impact in the price of products sold and raw materials would be recorded in the accounts Net Sales and Cost of Sales, respectively, in the Consolidated Statements of Income. The Company does not expect to be more vulnerable to a change in one or more specific product or raw material.

Sensitivity analysis of currency forward contracts: as of March 31, 2026, the Company has exposure to Dollar forward contracts for some of its assets and liabilities. The sensitivity analysis performed by the Company considers the effects of a 5% increase or decrease in the Dollar against the Real, and its effects on the mark-to-market valuation of these derivatives. A 5% increase in the Dollar against the Real represents an expense of R$ 6,431 (R$ 0 on March 31, 2025), and a 5% decrease in the Dollar against the Real represents revenue of the same value. The Dollar/Real forward contracts were intended to hedge asset and liability positions in Dollars, and the mark-to-market effects of these contracts were recorded in the Consolidated Income Statement.

Sensitivity analysis of commodity forward contracts: As of March 31, 2026, the Company has exposure to commodity derivatives (coal and energy). The sensitivity analysis performed by the Company considers the effects of a 5% increase or decrease in the price of commodities, and their effects on the mark-to-market valuation of these derivatives. A 5% increase in the price of commodities represents gain of R$ 3,624 (loss of R$ 2,882 as of March 31, 2025), and a 5% decrease in the price of commodities represents an expense of the same amount. The mark-to-market effects of these derivatives were recorded in the Consolidated Income Statement. The commodity derivatives to which the Company is exposed are presented in Note 14.e.

Sensitivity analysis of USD x DI swaps: the Company has USD x DI swaps to protect some of its Loans and financing. The sensitivity analysis carried out by the Company considers the impact on the MTM of a 5% increase in the Dollar against Real for all vertices of the respective operations. This variation would represent a gain of R$ 8,129 (gain of R$ 1,417 as of March 31, 2025). These effects would be recognized in the Consolidated Income Statement. The USD x DI swaps that the Company is exposed to are presented in Note 14.e.

Sensitivity analysis of IPCA x DI swaps: the Company has IPCA x DI swaps to protect some of its loans and financing. The sensitivity analysis carried out by the Company considers the impact on MTM of a 50 bps increase in the real yield curve for all vertices of the respective operations. This variation would represent a gain of R$ 611 as of March 31, 2026 (R$ 0 as of March 31, 2025). These effects would be recognized in the Consolidated Income Statement. The IPCA x DI swaps to which the Company is exposed to are presented in Note 14.e.

d) Financial Instruments per Category

Summary of the financial instruments per category:

GERDAU S.A.

NOTES TO THE CONDENSED CONSOLIDATED INTERIM FINANCIAL STATEMENTS

as of March 31, 2026

(In thousands of Brazilian Reais – R$, unless otherwise stated)

(Unaudited)

e) Operations with derivative financial instruments

Risk management objectives and strategies: In order to execute its strategy of sustainable growth, the Company implements risk management strategies in order to mitigate market risks.

The objective of derivative transactions is always related to mitigating market risks as stated in our policies and guidelines. All derivative instruments in force are monthly reviewed by the Financial Risk Committee, which validates the fair value of such instruments. All gains and losses on derivative instruments are recognized at their fair value in the Company’s consolidated financial statements in the line of Gains (Losses) on financial instruments, net.

Policy for use of derivatives: The Company is exposed to various market risks, including changes in exchange rates, commodities prices and interest rates. The Company uses derivatives and other financial instruments to reduce the impact of such risks on the fair value of its assets and liabilities or in future cash flows and income. The Company has established policies to evaluate the market risks and to approve the use of derivative transactions related to these risks. The Company enters into derivative financial instruments solely to manage the market risks mentioned above and never for speculative purposes. Derivative financial instruments are used only when they have a related position (asset or liability exposure) resulting from business operations, investments and financing.

Policy for determining fair value: the fair value of derivative financial instruments is determined using models and other valuation techniques, including future prices and market curves.

Derivative transactions may include interest rate and/or currency swaps, currency futures contracts and currency options contracts.

GERDAU S.A.

NOTES TO THE CONDENSED CONSOLIDATED INTERIM FINANCIAL STATEMENTS

as of March 31, 2026

(In thousands of Brazilian Reais – R$, unless otherwise stated)

(Unaudited)

Currency forward contracts: The Company may contract forward contract operations, through which it receives/pays a fixed Dollar amount and receives/pays a fixed Real/Argentinian Peso amount. Counterparties are always top-tier financial institutions with low credit risk.

Swap Contracts: The Company may contract a swap contract operation, through which it exchanges interest rate indices or local and/or foreign currency. Counterparties are always top - tier financial institutions with low credit risk.

The derivatives instruments can be summarized and categorized as follows: