Earnings release
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2 ri@brasil.isaenergia.com São Paulo, August 03, 2026 – ISA ENERGIA BRASIL S.A. (“ISA ENERGIA BRASIL”, the “Company”, B3: ISAE3 and ISAE4) announces its results for the second quarter of 2026 ( 2Q26). Regulatory results are presented in accordance with the procedures and guidelines issued by the regulatory authority and in compliance with the accounting policies established in the Electricity Sector Accounting Manual (“MCSE”), with the purpose of supporting the understanding of the Company’s business. Regulatory results are audited annually by the same independent auditor of the statutory financial statements and are not reviewed on a quarterly basis. Additionally, results prepared in accordance with the rules issued by the Brazilian Securities and Exchange Commission (“CVM”) and the applicable technical pronouncements of the Brazilian Accounting Pronouncements Committee (“CPC”), and in compliance with the International Financial Reporting Standards (“IFR S”) issued by the International Accounting Standards Board (“IASB”), can be found in the “Appendices” section of this document. ¹ Adjusted by non-controlling interest. Conference 2Q26 Conference call in Portuguese with simultaneous translation into English Date: August 04, 2026 Time: 10h00 (BRT) / 09h00 (EDT) The event will be streamed on Zoom: click here All connection data is available on the Investor Relations website: ri.isaenergiabrasil.com.br/en Regulatory Indicators (R$ million) 2Q26 2Q25 Chg (% ) 1H26 1H25 Chg (% ) Net Revenue 1,243.4 1,028.6 20.9% 2,469.6 2,160.5 14.3% PMSO -210.8 -186.7 13.0% -389.9 -364.4 7.0% Manageable PMSO -209.5 -184.7 13.4% -387.2 -360.6 7.4% EBITDA 966.9 789.5 22.5% 1,988.1 1,712.8 16.1% EBITDA Margin 77.8% 76.8% 1.0 p.p 80.5% 79.3% 1.2 p.p Net Income¹ 173.9 255.6 -32.0% 531.6 593.0 -10.4% Net Margin 14.0% 24.9% -10.9 p.p 21.5% 27.4% -5.9 p.p ROE (LTM) 17.1% 18.0% -0.9 p.p 17.1% 18.0% -0.9 p.p Net Debt 16,289.9 12,830.5 27.0% 16,289.9 12,830.5 27.0% CapEx (ex-M&A) 1,053.5 1,102.1 -4.4% 2,275.9 2,210.1 3.0% Consolidated EBITDA R$ 966.9 million (+22.5%) CapEx R$ 1,053.5 million (-4.4%) Net Revenue R$ 1,243.4 million (20.9%) Net Debt R$ 16,289.9 million (+27.0%) PMSO: R$ 210.8 million (+13.0%) Financial highlights 2Q26
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3 ri@brasil.isaenergia.com EVENTS OF THE PERIOD Common Share Conversion At the Board of Directors meeting held on March 19, 2026, the opening of the conversion period for common shares (ISAE3) into preferred shares (ISAE4) was approved, pursuant to the Company’s Bylaws. The Conversion Period took place between March 20 and April 3, 2026, subject to the global limit of up to 5% of the capital stock and the individual statutory limit of up to 3%, upon compliance with the applicable legal, statutory and operational requirements. At the meeting held on April 7, 2026, the Board of Directors acknowledged the requests received, resolved to ratify the requests that fully met the established requirements and approved the conversion of 19,767,728 common shares into preferred shares. Requests that did not comply with the documentary and/or operational requirements were rejected, and all acts adopted by the Investor Relations area necessary to implement the process were ratified. For more information, access the link. 22nd Debenture Issuance On April 6, 2026, the Company concluded the fundraising through the 22 nd issuance of simple debentures, not convertible into shares, in the total amount of R$ 1.0 billion, distributed in two series: (i) R$ 750 million in the first series; and (ii) R$ 250 million in the second series. The debentures have a 15-year term and cost of IPCA + 6.46% per year, corresponding to a spread of -87 bps over NTN -B 40. The proceeds raised were fully allocated to finance the Itatiaia Project. Access the link for more information. Energization of the Jacarandá Project On April 17, 2026, the Company obtained from the National Electric System Operator (“ONS”) the Final Release Term (“TLD”) for the Jacarandá project and started its commercial operation, with retroactive receipt of AAR as of April 11, 2026. The project was awarded in Transmission Auction No. 01/2022 held by the Brazilian Electricity Regulatory Agency (“ANEEL”) and consisted of the expansion of the Água Azul Substation, which received an additional 60 thousand m² of area, with the expansion of the 440 kV yard and the implementation of a new 88 kV yard. The project also included the installation of seven power transformers, which reinforced the supply capacity of the local electric system and added 600 MVA of capacity to the substation. With this energization, the Company began receiving the project’s Annual Allowed Revenue (“AAR”) of R$ 16.9 million (2026/2027 tariff cycle), with an estimated EBITDA margin of approximately 90% and a presumed profit tax regime. The project’s total investment was approximately R$ 188.8 million, representing a 33% efficiency compared to ANEEL CAPEX updated to the base date of March 30, 2026. Click here for more information. Obtaining the Installation License for the Serra Dourada Project (Block 2) On May 27, 2026, the Company obtained from the Institute of the Environment and Water Resources (“INEMA”) the Installation License (“LI”) for the remaining block (Block 2) of the Serra Dourada project. With the LI obtained, construction works on this 500 k V section of the Juazeiro III – Campo Formoso II - Barra II transmission line has already begun. Serra Dourada was awarded Transmission Auction No. 01/2023, held in June 2023 by ANEEL, and consists of the implementation of 1,093 km of transmission lines and three new substations, in addition to the expansion of three other substations already in operation. The project will create a priority corridor for the flow of renewable energy from western Bahia, enabling the connection of new and existing generators and new transmission projects. With the maximum deadline established by ANEEL for the Serra Dourada project to start operations in March 2029, the project has ANEEL CAPEX of R$ 3,157 million (auction date) and Annual Allowed Revenue (“AAR”) of R$ 337.0 million (2026/2027 cycle). Click here for more information. Energization of the Piraquê Project On June 11, 2026, the Company obtained from ONS the TLD for Block 3 of the Piraquê project. With the release granted, the remaining block started commercial operation 16 months ahead of the deadline established by ANEEL, and the Company began operating and being fully remunerated for Lot 3 awarded in Transmission Auction No. 01/2022. The project, one of the largest greenfield projects in the Brazilian transmission sector, involved the implementation of eight transmission lines, seven 500 kV lines and one 345 kV line, totaling approximately 1,000 km in length across the
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4 ri@brasil.isaenergia.com states of Minas Gerais and Espírito Santo. Block 3 included the construction of two transmission lines in Espírito Santo and the expansion of the substations associated with them. The project plays a relevant systemic role by significantly reducing the risk of overloads in the electric system in scenarios of high energy exchanges between the Northeast and Southeast regions, while reinforcing the stability of the transmission grid in the state of Espírito Santo, increasing energy flow capacity and reducing the risk of operational failures. With this energization, the Company began fully receiving the project’s AAR of R$ 359.3 million (2026/2027 tariff cycle), with an estimated EBITDA margin of approximately 95% and a real profit tax regime. The project’s total investment was approximately R$ 3.85 billion and was fully financed through green infrastructure debenture s. Click here for more information. Annual Allowed Revenue (“AAR”) 2026/2027 Cycle On June 22, 2025, Order No. 2,268 was published, establishing the AAR of ISA ENERGIA BRASIL and its subsidiaries and jointly controlled companies for the 2026/2027 Tariff Cycle, covering the period from July 1, 2026 to June 30, 2027 (“2026/2027 Cycle”). Below is a summary table of the consolidated AAR, weighted by the Company’s interest in the zjointly controlled companies: After July 31, 2026, the Company began consolidating 100% of IE Madeira’s AAR, as a result of the asset swap transaction carried out with AXIA Energia. The asset swap also resulted in the sale of 51% interest in IE Garanhuns, as disclosed. As a result, AAR for the 2026/2027 Cycle totals R$ 7,082 million. For further details, see the AAR section of this document. Below is a summary table of consolidated AAR, weighted by the Company’s interest in jointly controlled companies: Paulista Concession 3,627 3,806 50 3,869 RBSE 1,899 1,989 1,989 O&M 059/2001 915 921 984 R&M 059/2001 813 897 897 New concessions 2,772 3,276 (66) 3,197 New concessions in operation 1,750 2,679 (66) 2,600 New concessions in construction 1,022 597 - 597 Total 6,399 7,082 (16) 7,066 Category AAR 25/26 Cycle (with PA) AAR 26/27 Cycle (ex-PA) PA AAR 26/27 Cycle (with PA) 50
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5 ri@brasil.isaenergia.com Notes on financial information The financial information presented in this document refers to the three-month period ended March 31, 2026, and was prepared in accordance with the standards, procedures and guidelines issued by the Regulatory Agency, as well as the accounting policies established in the Electricity Sector Accounting Manual, approved by ANEEL through Normative Resolution No. 933, dated May 28, 2021, and the guidelines set forth in ANEEL’s Order No. 2,904, dated September 17, 2021. The information referred to as EBITDA (Earnings Before Interest, Taxes, Depreciation and Amortization) is presented in accordance with CVM Resolution 156/22. Additionally, the financial and operating information included in this results discussion is subject to rounding and, as a result, total amounts shown in tables and charts may differ from the direct numerical aggregation of the figures that preceded them. Below is the calculation of EBITDA under regulatory accounting in accordance with Normative Resolution No. 933 and Order No. 2,904: The calculation of EBITDA in accordance with accounting practices adopted in Brazil and International Financial Reporting Standards (“IFRS”) issued by the International Accounting Standards Board (“IASB”) based on EBITDA as per regulatory accounting is available in the section “Comparison of Results (Regulatory vs. IFRS)” (click here). (R$ million) 2Q26 2Q25 Var (% ) 1H26 1H25 Var (% ) (=) Net Profit IFRS 688.6 215.2 220.0% 1,297.7 928.4 39.8% (+) Non-controlling shareholder particp. 14.8 17.1 -13.7% 24.8 28.6 -13.1% (+) IRPJ/CSLL 137.4 -176.2 n.a 268.1 13.3 1909.4% (-) Equity Income -168.4 -138.8 21.3% -299.3 -294.2 1.7% (+) Financial Result 639.2 351.9 81.6% 1,122.3 703.5 59.5% (+) Depreciation/Amortization 9.4 8.3 12.5% 18.1 16.9 7.2% (=) EBITDA IFRS 1,321.0 277.5 376.1% 2,431.8 1,396.6 74.1% (+) Equity Income 168.4 138.8 21.3% 299.3 294.2 1.7% (=) EBITDA IFRS CVM 156/2022 1,489.3 416.3 257.8% 2,731.0 1,690.7 61.5% Consolidated
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6 ri@brasil.isaenergia.com ÍNDICE EVENTS OF THE PERIOD 3 OPERATING REVENUE 8 EBITDA AND MARGIN 11 FINANCIAL RESULT 12 EQUITY INCOME 13 IRPJ AND CSLL 14 NET INCOME¹ 14 COMPARISON OF RESULTS (REGULATORY VS. IFRS) 15 INDEBTEDNESS 17 INVESTMENTS 18 INVESTMENTS IN RETROFITTING AND IMPROVEMENTS PROJECTS (“R&I”) 18 INVESTIMENTS IN GREENFIELD PROJECTS 19 CAPITAL MARKETS 20 OWNERSHIP BREAKDOWN 20 SUSTAINABILITY 21 SUSTAINABILITY KPI’S 21 OTHER RELEVANT INFORMATION 25 REVISÃO TARIFÁRIA PERIÓDICA (RTP) - CONTRATOS LICITADOS 25 PAULISTA CONCESSION RENEWAL - CONTRACT 059/2001 (RBNI/RBSE) 28 SUPPLEMENTARY RETIREMENT PLAN – LAW 4,819/58 29 GLOSSARY 31 ATTACHMENTS 34
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7 ri@brasil.isaenergia.com OPERATING PERFORMANCE For transmission assets with voltage levels below 230 kV, associated with connection points to distribution companies, the main operational performance indicator is the Non‑Supplied Energy Index (“IENS ”). IENS corresponds to the percentage ratio between the total volume of energy not supplied to distribution agents during the events recorded in the period and the total energy that would have been supplied in the absence of interruptions. This indicator therefore reflects the amount of energy that was not consumed by end customers as a result of failures or interruptions in the system. Below is the Company’s IENS¹² measurement for the second quarter of 2026: 1 Connection assets associated with distribution companies with voltage levels below 230 kV are considered. 2 Data in the June/2026 report from SIN (National Interconnected System). Variable Portion The Variable Portion (“PV”) corresponds to the portion of the transmission concessionaire’s revenue that varies according to the availability of transmission facilities, in accordance with applicable regulatory rules. Any outages or failures exceeding the established regulatory thresholds may result in reductions to this revenue. The PV indicator applies to assets of the basic transmission grid with voltage levels equal to or above 230 kV and is calculated as the ratio between the gross PV for the period and the amount of AAP. After the impact of a significant outage recorded in January, PV performance in 2Q26 mainly reflected scheduled interventions related to the modernization and expansion of the grid, in addition to maintenance activities and specific operational events at transmission facilities. * PV data are dynamic and may be subsequently revised as a result of the conclusion of proceedings and appeals filed with the ONS. Asset Availability (%) *Only the basic network assets are considered **The National Electricity System Operator (ONS) calculates the indicator for families of equipment, which is the combination of type and voltage. ***Data accumulated in the form of a moving window. ****Source: ONS.
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8 ri@brasil.isaenergia.com FINANCIAL PERFORMANCE (Regulatory Results) Operating Revenue ¹ AAR related to the operation and maintenance portion of existing assets considered in the renewal process of contract 059/2001. Consolidated gross revenue reached R$ 1,421.2 million in 2Q26, an increase of R$ 247.4 million compared to 2Q25 (+21.0%). In 1H26, consolidated gross revenue increased by R$ 346.5 million (+14.0%) compared to 1H25. In addition to the tariff cycle adjustment for the 2025/2026 cycle, with AAR updated by the Broad Consumer Price Index (“IPCA”) for the period (5.32%), the main revenue variations in the period were: Paulista Concession (contract 059/2001) ▲ Incorporation of the AAR from large-scale Retrofitting and Improvements (“R&I”) projects energized over the last 12 months; ▼ Reduction in the RBSE financial component after ANEEL’s Board of Directors’ decision in June 2025. Auctioned Contracts ▲ Energization of the Água Vermelha Project (2Q25) and the Riacho Grande Project (4Q25), as well as the gradual energization of the Piraquê Project, which started recognizing 30% of its AAR as of November 2025 and 61% as of February 2026. The project reached full commercial operation during 2Q26 and began receiving 100% of its AAR as of May 31, 2026. Finally, the Jacarandá Project started commercial on March 30, 2026, with the Final Release Term (TLD) effective on April 11, 2026. Operating Revenue (R$ million) 2Q26 2Q25 Chg (% ) 1H26 1H25 Chg (% ) Eletric Network Revenue 1,413.0 1,163.6 21.4% 2,795.3 2,445.4 14.3% RBSE 511.5 568.6 -10.0% 1,023.1 1,137.2 -10.0% Paulista Concession (059/2001 contract) 497.5 435.8 14.2% 1,002.4 893.7 12.2% Operating & Maintenance (O&M)¹ 238.3 235.1 1.3% 476.5 470.3 1.3% Retrofitting & Improvements (R&I) 259.2 200.6 29.2% 525.9 423.5 24.2% New Concessions 369.7 254.7 45.2% 687.6 487.0 41.2% Adjustment Portion (PA) and anticipation 6.7 -112.2 n.a 43.7 -111.4 n.a Variable Portion (PV) -12.6 -12.7 -0.7% -33.7 -28.6 17.6% Regulatory charges ex RAP (CDE and PROINFA) 40.2 29.4 36.4% 72.1 67.5 6.9% Others 8.2 10.5 -22.5% 19.4 22.7 -14.7% Gross Revenue 1,421.2 1,174.1 21.0% 2,814.6 2,468.1 14.0% Deduction -177.8 -145.5 22.2% -345.0 -307.6 12.1% Taxes and Contributions (PIS & Cofins) -122.3 -101.4 20.7% -242.5 -213.9 13.4% Regulatory charges ex AAR (CDE and PROINFRA) -36.8 -26.5 38.9% -65.0 -59.1 10.0% Regulatory charges in AAR (P&D, RGR and TFSEE) -18.7 -17.7 5.7% -37.5 -34.7 8.2% Net Revenue 1,243.4 1,028.6 20.9% 2,469.6 2,160.5 14.3% Consolidated
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9 ri@brasil.isaenergia.com Adjustment Portion (“PA”) and Anticipation ▲ End of the amortization of the Ke portion in the RBSE financial component following ANEEL’s Board of Directors’ decision on June 10, 2025. The balance of this PA, recognized in 2020 after the first RTP of the Paulista Concession, with amortization extended until 2028 after the reprofiling of the RBSE financial component, had been amortized monthly in line with its receipt through AAR; ▲ Higher volume of anticipation related to the sector’s collection surplus or deficit (+R$ 41.6 million); ▲ Improvement of R$ 9.7 million associated with the tariff cycle adjustment PA (2024/2025 vs. 2025/2026) . ▼ Reimbursement of the Energy Development Account (“CDE”): CDE is classified as a pass -through item and does not constitute revenue for the Company, which changed its accounting treatment so that CDE would no longer flow through the income statement as of Au gust 2025, since the gross CDE revenue recorded was fully provisioned in the subsequent month; ▼ End of the retroactive receipt of the improvement’s annuity related to the 2023/2024 tariff cycle in June 2025, due to the postponement of the RTP from July 2023 to July 2024. NET REVENUE Net revenue increased by R$ 214.7 million (+20.9%) compared to 2Q25, totaling R$ 1,243.4 million. In 1H26, net revenue increased by R$ 309.2 million (+14.3%) compared to 1H25. ¹ Considers adjustment by the IPCA and project energization | ² Includes RBSE PA in 2Q25 | ³ Charges and taxes on revenue Net revenue ex-RBSE reached R$ 779.2 million in 2Q26, an increase of R$ 266.5 million (+52.0% vs. 2Q25). In addition to the tariff cycle adjustment for inflation, the decrease in RBSE was offset by the lower impact of PAs and by the energization of large-scale R&M projects and greenfield projects over the last 12 months. In 1H26, net revenue ex -RBSE increased by R$ 412.7 million (+36.6%) vs. 1H25. PA + Anticipations + Reimbursements (R$ Million) 2Q26 2Q25 Chg (% ) 1S26 1S25 Chg (% ) PA Cycle Readjustment 0.2 -9.5 n.a. 4.7 -16.7 n.a. PA RBSE and RTP 0.0 -131.7 -100.0% 0.0 -154.6 -100.0% RBSE 0.0 -131.7 -100.0% 0.0 -154.6 -100.0% RTP 0.0 0.0 n.a. 0.0 0.0 n.a. Improvements annual payment 11.0 20.5 -46.4% 22.0 40.9 -46.4% Anticipation (Sector Surplus | Deficit)) -4.5 -46.1 -90.3% 17.1 -89.9 n.a. CDE Reimbursement 0.0 54.6 -100.0% 0.0 108.9 -100.0% TOTAL 6.7 -112.2 n.a. 43.7 -111.4 n.a. Consolidated Net Revenue (R$ million) Net Revenue – 2Q26 vs. 2Q25 (R$ million) Net Revenue – 1H26 vs. 1H25 (R$ million)
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10 ri@brasil.isaenergia.com O&M Costs and Expenses The manageable portion of Personnel, Material, Services and Other costs and expenses (“PMSO”) totaled R$ 209.5 million in 2Q26 (+13.4% vs. 2Q25). The accumulated variation was +7.4% vs. 1H25. The main events that caused variations in manageable PMSO during the period were as follows: ▲ Personnel: higher costs related to salaries, payroll charges and benefits, and higher expenses associated with severance payments following terminations. This increase was partially offset by: (i) higher capitalization of technical staff hours; and (ii) lower expenses following the migration of the health insurance. ▲ Services: (i) recognition of success fees following the dismissal by the Federal Court of Accounts (“TCU”) of the proceeding related to RBSE; (ii) higher expenses with the maintenance of substations and transmission lines; and (iii) expenses with conservation, right -of-way clearing, mowing services and area inspection. The effects were partially offset by lower consulting expenses. ▲ Others: higher costs and expenses associated with: (i) IPTU, mainly due to the update of the market value of properties; (ii) software licenses and the acquisition of new software; and (iii) vehicle and property rentals. These effects were partially offset by lower leasing expenses. The chart below shows the evolution of the Company’s operating efficiency, measured by the ratio between PMSO and net revenue excluding RBSE. CONTINGENCIES The Company recorded contingencies totaling R$ 3.7 million in 2Q26, lower than 2Q25 (R$ 18.8 million), which had been mainly impacted by judicial enforcements arising from the adherence to ANEEL’s “Desenrola Program” for regulatory penalties in the amount of R$ 5.0 million and by provisions for civil proceedings totaling R$ 6.8 milli on. O&M Costs and Expenses (R$ million) 2Q26 2Q25 Chg (% ) 1H26 1H25 Chg (% ) Personnel -108.9 -102.0 6.8% -215.3 -210.1 2.5% Material -7.2 -7.1 2.0% -11.0 -11.2 -2.3% Services -62.8 -52.0 20.7% -107.9 -92.0 17.4% Others -30.5 -23.6 29.3% -53.0 -47.3 11.9% Manageable PMSO -209.5 -184.7 13.4% -387.2 -360.6 7.4% Non-recurring 0.0 0.0 N.A. 0.0 0.0 N.A. Private Pension Entity -1.4 -1.9 -29.6% -2.7 -3.8 -29.6% PMSO -210.8 -186.7 13.0% -389.9 -364.4 7.0% Contingencies -3.7 -18.8 -80.1% -4.4 -20.6 -78.9% Depreciation -222.1 -215.8 2.9% -391.6 -423.8 -7.6% Other costs and expenses -225.8 -234.6 -3.7% -395.9 -444.4 -10.9% Total -436.7 -421.2 3.7% -785.9 -808.8 -2.8% Consolidated Efficiency Indicator (R$ million)
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11 ri@brasil.isaenergia.com DEPRECIATION The Company recorded R$ 222.1 million in depreciation expenses in 2Q26, a 2.9% increase (R$ 6.3 million) compared to the depreciation recorded in 2Q25, mainly due to: ▲ Unitization of assets under auctioned contracts (+R$ 16.6 million vs. 2Q25). ▲ Regularization of unitizations of R& I projects under the Paulista Concession, with a one -off retroactive depreciation of R$ 4.7 million; ▲ Unitization of R&I projects under the Paulista Concession over the last 12 months (+R$ 2.6 million); ▼ End, in June 2025, of the deferred depreciation of RBSE assets, which had a quarterly amount of R$ 51.9 million. This depreciation refers to the period between the renewal of the Paulista Concession contract (Jan/2013) and the beginning of payment of the R BSE economic component (Jun/2017), which was amortized over eight years in accordance with regulation; As a result, Operating Costs and Expenses totaled R$ 436.7 million in 2Q26 (+3.7% vs. 2Q25), an increase of R$ 15.4 million. Other Operating Income and Expenses * Costs associated with the decommissioning, disposal and write-off of assets. ISA ENERGIA BRASIL recorded an expense of R$ 61.9 million under “Other Operating Income and Expenses” in 2Q26 (+83.9% vs. 2Q25), mainly due to costs related to the decommissioning of assets associated with dismantling activities carried out in Retrofitting and Improvements projects. The increase in these costs reflects the higher volume of investments and project energization in the period which required the replacement of existing assets. EBITDA and MARG IN 2Q26 EBITDA totaled R$ 966.9 million, an increase of R$ 177.3 million (+22.5% vs. 2Q25), with a margin of 77.8% (+1.0 p.p. vs. 2Q25). The variation is mainly explained by: ▲ Start of operations of greenfield projects and large-scale R&I projects over the last 12 months; ▲ Operating efficiency gains, with revenue growth outpacing expense growth; ▼ Reduction in the RBSE financial component following ANEEL’s decision in June 2025; ▼ End, in June 2025, of the retroactive receipt of the improvement’s annuity related to the 23/24 tariff cycle; and ▼ Higher costs related to the decommissioning and disposal of assets. Other Operating Income and Expenses (R$ million) 2Q26 2Q25 Chg (% ) 1H26 1H25 Chg (% ) Income 7.2 4.8 52.0% 16.1 11.5 39.6% Disposal of Non‑Operational Assets 2.5 1.7 41.2% 4.8 6.4 -25.7% Update of amounts of warrants receivable (SJC terrain) 3.0 3.0 -0.7% 5.9 4.8 21.4% Insurance Indemnity Proceeds 0.0 0.0 N.A. 1.9 0.3 636.3% Gain and Remuneration From SE Centro 1.8 0.0 N.A. 3.6 0.0 N.A. Expenses -69.1 -38.4 80.0% -103.4 -73.9 39.8% Disposal of Non‑Operational Assets -4.3 -3.2 35.3% -7.5 -5.6 35.1% Amortization of capital gains (PBTE and SF Energia) -13.5 -14.1 -4.3% -27.0 -28.3 -4.3% Cost of decommissioning assets* -51.3 -21.1 143.0% -68.8 -40.1 71.6% Others 0.0 0.0 N.A. 0.0 -0.3 n.a Total -61.9 -33.7 83.9% -87.3 -62.7 39.2% Consolidated EBITDA (R$ million) 2Q26 2Q25 Chg (% ) 1H26 1H25 Chg (% ) Net revenue 1,243.4 1,028.6 20.9% 2,469.6 2,160.5 14.3% Costs and expenses (ex-depreciation) -214.6 -205.4 4.5% -394.3 -385.0 2.4% Other expenses and revenues (ex-amortization) -61.9 -33.7 84.0% -87.3 -62.7 39.3% EBITDA 966.9 789.5 22.5% 1,988.1 1,712.8 16.1% EBITDA Margin 77.8% 76.8% 1 p.p. 80.5% 79.3% 1,2 p.p. Consolidated
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12 ri@brasil.isaenergia.com The EBITDA from ISA ENERGIA BRASIL’s interest in jointly controlled companies totaled R$ 181.4 million in 2Q26, an increase of R$ 10.7 million (+6.3%) compared to 2Q25. In the accumulated period (1H26), EBITDA from ISA ENERGIA BRASIL’s interest in jointly controlled companies totaled R$ 361.7 million, up 7.8% vs. 1H25. Total EBITDA, considering ISA ENERGIA BRASIL’s consolidated results and its interest in jointly controlled companies, was R$ 1,148.3 million in 2Q26 (+19.6% vs. 2Q25). In addition to the increase in Consolidated EBITDA, EBITDA from all jointly controlled c ompanies also grew in 2Q26. More details are available in the “Equity Pickup” section of this document (click here). Financial Result The Company recorded net financial expenses of R$ 638.9 million in 2Q26, an increase of R$ 287.2 million (+81.7%) compared to 2Q25. In the accumulated period for 1H26, net financial expenses increased by 59.5% to R$ 1,121.8 million, compared to the expense of R$ 703.1 million recorded in 1H25, mainly impacted by: ▲ Monetary variation: the increase is mainly due to the higher gross debt position indexed to IPCA (+R$ 4.0 billion) and, consequently, to the greater share of IPCA as an indexer of the Company’s debt, which increased from 56% in 2Q25 to 67% in 2Q26. In addition to the Company’s higher debt exposure to IPCA, the inflation index advanced 89 bps in the period (2.14% in 2Q26 vs. 1.25% in 2Q25). For accounting purposes, 2Q considers inflation from March to May; ▲ Interest and charges on loans: reflect the higher average debt balance, driven by the funding raised over the last 12 months to finance the Company’s growth (19th, 20th and 22nd debentures), totaling R$3.6 billion. This was partially offset by the reduction in the overall cost of debt resulting from the liability management transaction carried out through the 21st debenture issuance in 1Q26, as well as the prepayment, in the same amount, of the 9th, 13th, 15th (1st, 2nd and 3rd series), and 16th debenture issuances, which reduced the average contracted spread by approximately 80 bps; ▼ Other financial income: decrease of R$ 51.1 million compared to the same period of the previous year, as the Company recognized, in 2Q25, financial income related to the update of extemporaneous IR/CSLL tax credits; and ▼ Income from financial investments: decrease of 13.3% vs. 2Q25 due to the lower average cash balance invested. EBITDA (R$ million) 2Q26 2Q25 Chg (% ) 1H26 1H25 Chg (% ) ISA ENERGIA BRASIL Consolidated 966.9 789.5 22.5% 1,988.1 1,712.8 16.1% Jointly-controlled subsidiaries 181.4 170.7 6.3% 361.7 335.6 7.8% IE Madeira (51%) 86.5 80.2 7.8% 168.8 155.1 8.9% IE Garanhuns (51%) 17.0 16.4 3.4% 35.2 32.5 8.3% IE Aimorés (50%) 12.7 11.9 7.2% 25.5 23.8 7.3% IE Paraguaçu (50%) 18.8 17.7 6.1% 37.9 35.2 7.8% IE Ivaí (50%) 46.4 44.4 4.5% 94.2 89.0 5.9% Total 1,148.3 960.2 19.6% 2,349.8 2,048.4 14.7% Consolidated + Non-consolidated Financial Result (R$ million) 2Q26 2Q25 Chg (% ) 1H26 1H25 Chg (% ) Financial Income 89.8 124.1 -27.7% 148.1 216.9 -31.7% Financial investment income 63.2 72.9 -13.3% 120.3 153.4 -21.5% Others 26.5 51.2 -48.1% 27.7 63.5 -56.3% Financial Expenses -728.7 -475.8 53.1% -1,269.9 -920.0 38.0% Interest and charges on loans -397.2 -325.8 21.9% -778.9 -599.7 29.9% Monetary variation -281.9 -124.0 127.4% -419.0 -159.1 163.3% Others -49.6 -26.1 90.1% -71.9 -161.1 -55.4% Total -638.9 -351.7 81.7% -1,121.8 -703.1 59.5% Consolidated
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13 ri@brasil.isaenergia.com Equity Income Equity income was R$ 79.3 million in 2Q26, a reduction of R$ 12.2 million (-13.4%) compared to 2Q25. In 1H26, equity income totaled R$ 163.1 million, down 2.1% vs. 1H25. Details by company are presented below: IE Madeira Increase of R$ 3.4 million (+7.5%) compared to 2Q25, reaching R$ 48.9 million in 2Q26. Performance was mainly explained by: (i) AAR adjustment for the 2025/2026 tariff cycle; (ii) lower incidence of the Variable Portion for Unavailability (“PVI”), reflecting the comparison base that was negatively impacted in 2Q25 (+R$ 1.0 million); and (iii) reduction in net financial expenses ( -R$ 2.8 million) due to the lower gross debt position. Accumulated equity income growth in 1H26 was R$ 14.6 million (+17.6%). IE Garanhuns Increased by R$ 0.4 million (+3.4%) compared to 2Q25, mainly due to the tariff cycle adjustment and the improvement observed in the financial result. In 1H26, IE Garanhuns posted an increase of 9.7% (+R$ 2.3 million). Aliança Interligação Elétrica (“AIE”) Comprising three projects in partnership with TAESA (Aimorés, Paraguaçu and Ivaí), AIE recorded a reduction of R$ 16.0 million in 2Q26 (-47.6% vs. 2Q25), mainly explained by: • IE Aimorés and IE Paraguaçu: higher financial expenses due to debt disbursements occurring at the end of 2Q25, partially offset by the tariff cycle adjustment by IPCA. • IE Ivaí: higher net financial expenses, mainly due to the IPCA variation in the period (+89 bps vs. 2Q25) and lower financial income due to the lower average cash balance invested. Click here to view the condensed income statement of jointly controlled companies. Equity Income (R$ million) 2Q26 2Q25 Chg (% ) 1H26 1H25 Chg (% ) IE Madeira (51% ) 48.9 45.5 7.5% 97.3 82.7 17.6% IE Garanhuns (51% ) 12.7 12.3 3.4% 26.2 23.9 9.7% AIE (50% ) 17.7 33.7 -47.6% 39.6 60.0 -34.1% IE Aimorés 6.5 9.9 -34.9% 12.8 19.4 -34.1% IE Paraguaçu 9.7 15.2 -35.8% 17.6 29.3 -39.9% IE Ivaí 1.5 8.6 -82.8% 9.1 11.2 -18.7% Total 79.3 91.5 -13.4% 163.1 166.6 -2.1% Consolidated
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14 ri@brasil.isaenergia.com IRPJ and CSLL The Company recorded current Income Tax and Social Contribution on Net Income (“IR/CSLL”) expenses of R$ 52.3 million in 2Q26, compared to income of R$ 11.3 million recorded in the same period of the previous year, a quarter in which the Company recognized an extemporaneous tax credit with a non -recurring positive impact of R$ 77.5 million. In addition, higher net financial expenses reduced taxable income, leading to the recognition of a positive deferred IRPJ/CSLL amount of R$ 55.8 million. Year-to-date, the result generated an expense of R$ 81.3 million, an increase of R$ 49.7 million vs. 1H25. The calculation is detailed below: Net Income ¹ As a result of the explanations presented, net income for the quarter totaled R$ 173.9 million, a decrease of R$ 81.8 million (-32.0%) compared to 2Q25. In the first half of 2026 (1H26), net income totaled R$ 531.6 million. ¹ adjusted by non-controlling interest. IRPJ|CSLL (R$ million) 2Q26 2Q25 Chg (% ) 1H26 1H25 Chg (% ) Current -52.3 11.3 n.a -135.5 -83.6 62.0% Deferred 55.8 -52.1 n.a 54.2 -47.3 n.a Total 3.4 -40.8 n.a -81.3 -130.9 -37.9% Effective rate -1.9% 13.0% -14,9 p.p 12.7% 17.4% -5 p.p Consolidated Tax Calculation IRPJ | CSLL (R$ million) Parent Company Consolidated Tax Regime Real Profit Presumed Profit Real Profit - (A) Earnings before IRPJ/CSLL (EBT) 586.4 253.5 32.1 637.7 (+/-) Adjustments¹ -425.2 0.0 0.0 0.0 Interest on Equity Paid 0.0 - 0.0 - Interest on Equity Received Subsidiaries 0.0 - - - Equity Income subsidiaries 100% -262.1 - - - Equity Income of jointly-controlled subsidiaries -163.1 - - - (=) Taxable base/result 161.2 253.5 32.1 637.7 Nominal tax rate -34% - -34% - (B) IRPJ and CSLL Current -54.8 -15.5 -10.9 -81.2 (C) Current Effective Tax Rate -9.4% -6.1% -34.0% -12.7% Subsidiaries (100% ) Fiscal Year 2026 Net Income¹ 1Q26 vs 1Q25 (R$ million) Net Margin 14.0% Net Margin 24.9% Net Income¹ 1H26 vs 1H25 (R$ million) Net Margin 21.5% Net Margin 27.4%
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15 ri@brasil.isaenergia.com Comparison of Results (Regulat ory vs. IFRS) In 2Q26, the Company recorded net income of R$ 688.6 million under IFRS accounting, R$ 473.4 million higher (+220.0%) than the amount recorded in 2Q25. The detailed Income Statement under IFRS accounting is available in Appendix IX of this document. Revenue - IFRS 15: As per IFRS, revenues from investments made during the concession period are booked with margin from construction of infrastructure and after determining the discount rate for assets under the contract. In addition, there is revenue from remuneration of assets under contract, which is the recomposition of the amount receivable from the discount rate over time. As per regulatory rules, revenue reflects the AAR recognized as billed during the concession period. Costs of investments : As per IFRS, infrastructure implementation costs refer to investments made during the construction period, calculated based on investments in Capex acquisitions (equipment, services and internal and external labor). As per regulatory rules, investments are treated as fixed assets. Depreciation: Pursuant to IFRS, there is no depreciation of concession assets since these are not considered fixed assets, but rather a financial asset or asset under contract. As per IFRS, fixed assets largely relate to assets used by the Company and are not linked t o the concession agreement. For Regulatory purposes, the concession assets are deemed fixed assets and depreciated on a straight-line basis over their useful life. Equity Income: The main effects of equity income reflect the explanations of revenue, costs and depreciation for the wholly owned subsidiaries. Income Tax/Social Contribution: As per IFRS, Income Tax/Social Contribution is provisioned monthly on an accrual basis and calculated pursuant to Law 12,973/14, such that the amounts taxed consider the realization of cash. The Company adopts the taxable income method and uses a monthly estimate. Income Statement (IFRS) (R$ million) 2Q26 2Q25 Chg (% ) 1H26 1H25 Chg (% ) Net Operating Revenue 2,597.5 1,432.9 81.3% 5,108.3 3,844.9 32.9% Costs of Infrastructure Implementation Services, operation and maintenance and services provided -1,209.5 -1,244.3 -2.8% -2,566.5 -2,490.7 3.0% Gross Profit 1,388.0 188.5 636.2% 2,541.8 1,354.2 87.7% Operational Revenue and Expenses 92.0 219.4 -58.1% 171.1 319.6 -46.5% Earnings before financial income and expenses and taxes on earnings 1,480.0 408.0 262.8% 2,712.9 1,673.8 62.1% Financial Income -639.2 -351.9 81.6% -1,122.3 -703.5 59.5% Earnings Before Taxes 840.8 56.1 1399.8% 1,590.6 970.3 63.9% Income tax and Social Contribution on Earnings -137.4 176.2 -178.0% -268.1 -13.3 1909.4% Consolidated Profit/Loss 703.4 232.3 202.8% 1,322.5 957.0 38.2% Non-Controlling Shareholder's Stake -14.8 -17.1 -13.7% -24.8 -28.6 -13.1% Consolidated Profit/Loss for the Period 688.6 215.2 220.0% 1,297.7 928.4 39.8% Consolidated
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16 ri@brasil.isaenergia.com Following is the calculation of EBITDA as per IFRS pursuant to CVM Resolution 156/22: Following is the calculation of EBITDA as per Regulatory accounting based on EBITDA CVM 156/22: (R$ million) 2Q26 2Q25 Var (% ) 1H26 1H25 Var (% ) (=) Net Profit IFRS 688.6 215.2 220.0% 1,297.7 928.4 39.8% (+) Non-controlling shareholder particp. 14.8 17.1 -13.7% 24.8 28.6 -13.1% (+) IRPJ/CSLL 137.4 -176.2 n.a 268.1 13.3 1909.4% (-) Equity Income -168.4 -138.8 21.3% -299.3 -294.2 1.7% (+) Financial Result 639.2 351.9 81.6% 1,122.3 703.5 59.5% (+) Depreciation/Amortization 9.4 8.3 12.5% 18.1 16.9 7.2% (=) EBITDA IFRS 1,321.0 277.5 376.1% 2,431.8 1,396.6 74.1% (+) Equity Income 168.4 138.8 21.3% 299.3 294.2 1.7% (=) EBITDA IFRS CVM 156/2022 1,489.3 416.3 257.8% 2,731.0 1,690.7 61.5% Consolidated (R$ million) 2Q26 2Q25 Chg (% ) 1H26 1H25 Chg (% ) EBITDA IFRS (CVM 156/22) 1,489.4 416.3 257.8% 2,731.1 1,690.8 61.5% (-) Infrastructure implementation revenue -1,599.4 -1,380.7 15.8% -3,287.2 -2,712.1 21.2% (-) Concession assets remuneration -916.0 64.6 -1517.4% -1,643.3 -942.6 74.3% (-) Efficiency gains in infrastructure implementation -29.6 17.9 -265.3% -48.6 10.7 -555.8% (-) O&M Revenue -350.7 -318.8 10.0% -706.1 -651.5 8.4% (+) Electric network use revenue 1,411.4 1,163.6 21.3% 2,793.2 2,445.4 14.2% (+) Other Revenue 1.3 1.0 28.3% 2.5 4.5 -44.7% (+) Deferred PIS and COFINS 128.9 48.2 167.4% 250.9 161.2 55.7% (+) Infrastructure implementation cost 1,052.0 1,102.1 -4.5% 2,271.4 2,210.1 2.8% (-) O&M Cost 3.0 7.8 -61.5% 7.5 12.0 -37.6% (-) General and Administrative expenses 11.8 3.9 198.2% 9.3 7.8 20.2% (-) Equity Income -89.1 -47.3 88.2% -136.2 -127.6 6.8% (-) Other operational revenues (expenses) -66.7 -31.2 113.9% -93.3 -63.0 48.2% REGULATORY EBITDA (CVM 156/22) 1,046.2 881.1 18.7% 2,151.1 1,879.4 14.5% Equity Income -79.3 -91.5 -13.4% -163.1 -166.6 -2.1% REGULATORY EBITDA 966.9 789.6 22.5% 1,988.1 1,712.8 16.1% Consolidated
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17 ri@brasil.isaenergia.com INDEBTEDNESS ¹ A part of the Company's funds is invested in exclusive investment funds, which are also used separately by the wholly -owned subsidiaries and jointly -controlled subsidiaries (IE Madeira, IE Garanhuns, IE Aimorés, IE Paraguaçu and IE Ivaí), and refer to sh ares in highly liquid investment funds that are easily convertible into cash, regardless of the maturity of the assets allocated to them. ² Net debt considers cash and cash equivalents of ISA ENERGIA BRASIL and wholly owned subsidiaries. ³ Considers leasing operations, according to the electricity sector accounting manual (" MCSE") in force since January 2022, which considers the adoption of CPC 6 by ANEEL. The Company’s gross debt reached R$ 17,725.7 million at the end of 2Q26, an increase of R$ 1,718.4 million (+10.7%) compared to the balance at the end of 4Q25. The Company also ended 2Q26 with total cash and cash equivalents of R$ 1,757.3 million (-18.8% vs. December 31, 2025). Excluding cash and cash equivalents of jointly controlled companies, on June 30, 2026, the Company’s net debt reached R$ 16,289.9 million, an increase of R$ 2,162.0 million (+15.3% vs. December 31, 2025). The increase in net debt was mainly due to: (i) a lower financial investment position following the payment of R$ 495.3 million in Interest on Equity during 1Q26, and R$ 1.1 billion of CAPEX deployed in 2Q26; (ii) 22nd debenture issuance (R$ 1.0 billion); and (iii) monetary variation on debt. The Company carried out the following fundraising transactions in 1H26: • 21st debenture issuance (R$ 3.9 billion): liability management , with proceeds fully allocated to the optional acquisition of the 9th, 13th, 15th (1st, 2nd and 3rd series) and 16th debenture issuances. The transaction contributed to optimizing the capital structure by extending the average term of prepaid debt by 2.7 years and reducing the average contracted spread by approximately 80 bps. • 22nd debenture issuance (R$ 1.0 billion): incentivized and green issuance in two series, maturing in 2041 and with a cost of IPCA + 6.46% p.a. The liability management transaction carried out through the 21 st debenture issuance in 1Q26 contributed to reducing the Company’s average nominal cost of debt, which stood at 12.17% p.a. as of June 30, 2026 (vs. 12.36% p.a. as of December 31, 2025). Considering the accumulated IPCA inflation rate over the last 12 month s, the average real cost* of debt was 7.11%, representing a reduction of 45 bps (vs. 7.56% as of December 31, 2025) . The average term of consolidated debt was 8.7 years as of June 30, 2026 (vs. 8.3 years as of December 31, 2025). The increase in the average term consolidates the Company’s long-term debt profile, which is compatible with the nature of the business, characterized by low risk, high revenue predictability and operating cash flow generation — characteristics highlighted by Fitch when assigning the Company a local -scale corporate rating of “AAA” with a stable outlook. In July 2026, the agency issued a report reaffirming the Company’s credit rating. It is worth noting that only the financing agreements with BNDES (R$ 665.0 million as of June 30, 2026) have financial covenants, which are measured annually by the Net Debt/EBITDA ratio recorded in 4Q and have a limit of 3.0x. In 2025, BNDES sent a letter formalizing its waiver of the declaration of early maturity of the Company’s financing agreements due to any potential breach o f the “Net Debt/Adjusted EBITDA” and/or “Net Debt /(Net Debt + Shareholders’ Equity)” indicators for fiscal year 2025. For further details, click here . The managerial leverage ratio, following BNDES DEBT R$ (million) Gross Debt³ 17,725.7 16,007.3 10.7% Short-term Debt 459.9 604.8 -23.9% Long-term Debt 17,265.8 15,402.6 12.1% Consolidated Availabilities 1,757.3 2,165.0 -18.8% ISA ENERGIA BRASIL and 1,435.8 1,879.4 -23.6% Jointly-controlled subsidiaries¹ 321.5 285.5 12.6% Consolidated Net Debt² 16,289.9 14,127.9 15.3% 06/30/26 12/31/25 Chg (% ) Gross debt amortization schedule (R$ million) Debt Indexation 30/06/2026
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18 ri@brasil.isaenergia.com methodology, was 3.78x in 2Q26, compared to 3.63x in 4Q25. More details on leverage are available in Appendix VII of this document, and further information on indebtedness is available on the Company’s website ( click here). (*) Ratio between (i) average nominal cost; and (ii) IPCA over the last 12 months. ¹ CDI 2Q25 3.27% - 2Q26 3.26% INVESTMENTS During 2Q26, ISA ENERGIA BRASIL, its subsidiaries and jointly controlled companies, invested R$ 1,053.5 million, R$ 48.7 million lower (-4.4%) than in 2Q25. This performance was mainly explained by lower investments in greenfield projects (-15.9%), reflecting the lower investment needs following the recent energizations of the Jacarandá and Piraquê projects, completed in April and June, respectively. On the other hand, investments in Retrofitting and Improvements (“R&I”) projects were R$ 66.1 million (+17.4%) higher than in the same period of 2025. As a result, total investments made in the first half of 2026 amounted to R$ 2,275.9 million, R$ 65.7 million higher (+3.0%) than in the same period of 2025. This growth is explained by the increase in investments in R& I projects, which represented 35.8% of total investments in the first half of 2026. Investments in Retrofitting and Improvements Projects (“R&I”) The Company invested R$ 445.4 million in R& I projects in 2Q26, an increase of R$ 66.1 million (+17.4%) compared to 2Q25. Throughout the first half of 2026, investments in R& I totaled R$ 815.4 million (+19.0%), reinforcing the Company’s commitment to efficient management, resilience and reliability of the transmission system. In addition to ensuring excellence in service delivery, asset renewal enables a reduction in O&M costs and increases operational efficiency and profitability. The Company replaced 312 assets and energized 16 R& I projects (13 small -scale and 3 large-scale) in 2Q26, with a total investment of R$290.8 million. In the first half of the year, energized investments totaled approximately R$475 million, of which 72% were allocated to small-scale projects and 28% to large-scale projects.
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19 ri@brasil.isaenergia.com Considering the investments made throughout 2Q26, the new authorizations obtained, cost updates during the period, and monetary adjustment by IPCA, the authorized R& I project portfolio totaled approximately R$ 7.2 billion at the end of 2Q26, to be executed by the Company over the coming years. These investments are remunerated in accordance with ANEEL’s authorization, and revenue from approximately 54% of the investmen ts authorized between February 2023 and June 2027 relates to small -scale projects and, therefore, will only be enabled in the Periodic Tariff Review (“RTP”) expected to take place in 2028, with retroactive revenue payment as of the respective commercial op eration dates of each project. Large -scale projects are authorized with revenue previously defined through an Authorizing Resolution (“ReA”) and begin receiving revenue immediately after starting operations. Invest ments in Greenfield Projects The Company invested R$ 608.1 million in auctioned projects in 2Q26, R$ 114.7 million lower (-15.9%) than the amount invested in the same period of 2025. The reduction is explained by the lower number of projects under construction following the energizations of the Jacarandá project, in April, and Block 3 of the Piraquê project, in June 2026. Together, the projects energized in 2Q26 enabled the receipt of AAR of R$ 376.2 million (2026/2027 cycle). The funds invested in the quarter were mainly allocated to the Serra Dourada project (R$ 455.7 million), which reached 49% physical progress in 2Q26, Piraquê (R$ 84.4 million) and Itatiaia (R$ 52.2 million), which ended the quarter with 33% physical progress. As a result, investments in auctioned projects totaled R$ 1,460.4 million in 1H26, a reduction of R$ 64.4 million (-4.2%) compared to 1H25. With the energization of Block 3 of the Piraquê project and the Jacarandá project, the Company continues with the planning and execution of two greenfield projects, Serra Dourada and Itatiaia, which have total AAR for the 2026/2027 cycle of R$ 596.9 million and approximately R$ 4.6 billion in remaining CAPEX. The table below presents information on the projects under construction: ¹Project Development: evolution of all activities related to the project until its energization. For more information about Greenfield projects, visit our website. Total ANEEL (as of jun/26) Actual (as of jun/26) Serra Dourada (Lot 1) Under construction 006/2023 ISA ENERGIA BRASIL BA/MG 337.0 3T25 Mar-29 49% 3,731.4 1,844.5 Itatiaia (Lot 7) Ambiental License 012/2023 ISA ENERGIA BRASIL RJ/MG 259.9 - Mar-29 33% 2,719.4 549.7 596.9 6,450.7 2,394.3 State AAR ISA ENERGIA BRASIL Cycle 26/27 (R$ million) Auction Project Current Status Contract Company Total (2) Physical Progress 001/2023 (jun/2023) Total CapEx - ISA ENERGIA BRASIL Participation (R$ million, in real terms) Start of Construction ANEEL Deadline
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20 ri@brasil.isaenergia.com CAPITAL MARKETS Ownership Breakdown Controlled by ISA, a multi -Latin company operating in the electricity, roads and telecommunications sectors, the Company had, as of June 30, 2026, 64.2% of its outstanding shares in circulation (free float). Data base: 30/06/2026. Stock Performance ISA ENERGIA BRASIL’s common shares (“ISAE3”) and preferred shares (“ISAE4”) ended 2Q26 trading at R$ 33.30 ( - 3.2% vs. the closing price in 1Q26) and R$ 28.11 (-3.4% vs. the closing price in 1Q26), respectively. In the same period, the Electric Energy Index (“IEE”) and Ibovespa (“IBOV”) decreased by 3.5% and 8.2%, respectively. The Company ended 2Q26 with a market capitalization of R$ 20.3 billion, and the average daily traded value (“ADTV”²) of ISAE4 in the quarter was R$ 81.7 million (+18.6% vs. 1Q26). ³ The ownership position reflects data as of the close of 2Q26, excluding the Primary Share Offering announced on July 15, 2026. Currently, the Company is part of 19 indices, notably Ibovespa, IEE, the Corporate Governance Index (“IGC”), the Dividend Index (“IDIV”) and the Corporate Sustainability Index (“ISE”). Shares % Shares % Shares % ISA Capital do Brasil S.A 230,856,832 96.93% 5,144,528 1.22% 236,001,360 35.82% Management - - - - - - Free Float 7,313,172 3.07% 415,568,772 98.78% 422,881,944 64.18% Axia Energia 5,340,330 2.24% 130,937,325 31.12% 136,277,655 20.68% Others 1,972,842 0.83% 284,631,447 67.65% 286,604,289 43.50% Total 238,170,004 100.00% 420,713,300 100.00% 658,883,304 100.00% Shareholders ISAE3 (common) ISAE4 (preferred) Total (common + preferred) Capital markets 2Q26 1Q26 4Q25 Number of shares 658,882,604 658,882,604 658,882,604 Market Capitalization¹ (R$ billion) 20.3 20.5 19.8 ISAE3 Average volume/day (thousand shares) 3.0 3.5 3.2 Average Daily Traded Volume (1,000 R$) 99 120 99 Average price (R$) 33.78 34.06 30.93 Closing price (R$) 33.30 34.39 34.00 ISAE4 Average volume/day (thousand shares) 2,822 2,439 2,699 Average Daily Traded Volume (1,000 R$) 81,681 68,876 80,919 Average price (R$) 28.76 28.12 24.26 Closing price (R$) 28.11 29.09 27.54 ¹ calculated based on the closing price of shares traded in the period | ² Average Daily Trading Volume Evolução ISAE3 x ISAE4 x Ibovespa x IEE – 2026 (base 100) ³
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21 ri@brasil.isaenergia.com SUSTAINABILITY The data and indicators presented refer to ISA ENERGIA BRASIL and its wholly owned subsidiaries, unless otherwise indicated in a footnote. The management of this information is overseen and reviewed by the Board of Directors, through the Environmental, Social and Corporate Governance Committee (“ESG”). Learn more about the sustainability commitments on the Company’s website. Highlights of the Period Progress on the climate agenda and recognition of the sustainability strategy The Company published its Annual Sustainability Report (“RAS”) and the 2025 Climate Journey Report, highlighting the evolution of its decarbonization and climate change adaptation strategy. The results presented include: (i) the established reduction targets of the Net Zero pathway by 2050; (ii) a cumulative 27% reduction in SF₆ emissions over the last four years; (iii) the strengthening of climate risk management; and (iv) investments focused on the resilience and reliability of the electric system. The consistent progress of this agenda was recognized by the market and, for the 4th consecutive year, the Company was included in B3’s Corporate Sustainability Index (“ISE”) portfolio. Read the full reports. Pioneering technology drives the decarbonization of electric infrastructure In partnership with Hitachi Energy, the Company began the installation of Latin America’s first 460 kV reactor using insulating vegetable oil, at the Bauru Substation (SP). The project includes the installation of four reactors and replaces fossil-based mineral oil with a renewable, biodegradable and low-toxicity alternative, reducing the environmental impact of the operation. In addition to contributing to the decarbonization of electric infrastructure, the technology offers greater operational safety due to its higher resistance to high temperatures and lower fire risk, reinforcing the reliability of the transmission system and supporting the Company’s energy transition strategy. *Except technical losses and the two new Scope 3 categories Sustainability KPI’s Performance of CO2 Emission Sources The Company maintained its focus on managing its operational emissions and asset efficiency in 2Q26, a period in which punctual SF₆ gas leaks were identified in some assets. In response, the Company intensified monitoring, inspection and maintenance action s, in addition to replacing components and correcting the identified occurrences, contributing to mitigating impacts and strengthening operational reliability. Also, in 2Q26, the Company recorded a 12% reduction in electricity consumption purchased from utilities compared to the same period of the previous year, mainly reflecting operational adjustments following the transfer of IE EVRECY, which was reauctioned in 2025. Fuel consumption increased by 4% in 2Q26 due to the progress of construction projects. However, it maintained the downward trend observed over recent periods. 1 considers electricity consumption exclusively from the utility.
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22 ri@brasil.isaenergia.com Occupational Health and Safety (“OHS”) In 2Q26, ISA ENERGIA BRASIL recorded a reduction in accident frequency rates, reflecting the progress of prevention actions through the dissemination of lessons learned, continuous communication on safety requirements and the execution of operational briefings, strengthening risk awareness and the preventive culture. The Company also intensified field inspection and supervision activities, with an increase in inspections, safety blitzes and stronger engagement of OHS teams in projects and critical operational fronts. Additionally, initiatives were promoted to engage leadership, monitor the performance of contractors and train execution teams, focusing on the adoption of safe behaviors and the continuous improvement of operational controls. These actions were complemented by awareness campaigns and systematic monitoring of action plans related to the main safety deviations and occurrences. These initiatives aim to strengthen OHS governance, mitigate operational risks and consolidate an increasingly preventive safety culture, contributing to the protection of people and to the safe and sustainable execution of the Company’s activities. Diversity ISA ENERGIA BRASIL’s Diversity, Equity, Inclusion and Belonging Program (“DEIB”) maintained its strategic approach focused on talent development, strengthening inclusive leadership and promoting a culture of belonging. During the period, highlights include d the implementation of the Mentoring Program for Women, the continuity of female development initiatives and actions related to LGBTI+ Pride Month, reinforcing the Company’s commitment to increasingly diverse, equitable and inclusive environments. For the next cycles, the Company will remain focused on expanding initiatives for the development of diverse talent, leadership training and strengthening governance in diversity, equity and inclusion. These initiatives contribute to attracting, retaining and developing talent, strengthening the employer brand and supporting the generation of sustainable value for the business. Diversity indicators consider the total number of employees as of the last day of each period. 1 Statutory Officers and the Chief Executive Officer. 2 Employed Officers, Managers and Coordinators. 3 Specialists and other positions, except for Board Members, Apprentices and Interns. 4 Ethnicity/race information is based on the classifications established by IBGE. Accidents with absense Employees 1 0 -1 2 1 -0.5 Third-parties Employees 9 5 -0 11 13 0.2 Total 10 5 -1 13 14 0.1 Accidents without absence Employees 0 0 N.A. 0 0 N.A. Third-parties Employees 3 1 -1 5 2 -0.6 Total 3 1 -1 5 2 -0.6 Accidents with Death Employees 0 0 N.A. 0 0 N.A. Third-parties Employees 0 0 N.A. 0 0 N.A. Total 0 0 N.A. 0 0 N.A. Accidents Frequency Rate Employees 1.3 0.0 -1 1.3 0.6 -0.5 Third-parties Employees 2.1 1.0 -0.5 1.5 1.3 -0.1 1H26 Chg (% ) Category / Employee 2Q25 2Q26 Chg (% ) 1H25 Ethnic Diversity (%)4 Gender (%)
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23 ri@brasil.isaenergia.com Ethical Conduct ISA ENERGIA BRASIL recorded 34 reports through the Ethics Line in 2Q26, compared to 20 reports in the same period of 2025, representing a 70% increase and indicating greater use of the integrity and reporting mechanisms made available by the Company. The website remained the main reporting channel, accounting for 76% of submissions, while 68% of reports were made anonymously, reinforcing stakeholders’ trust in the reporting channels. The occurrences were concentrated on matters related to disrespectful treatment and non-compliance with laws, rules and procedures. Of the reports received, 47% were classified as out of scope, 35% were not confirmed after investigation, 12% were confirmed and 6% remained under review as of the closing date of the period. Four cases were confirmed after investigation and handled in accordance with the Company’s governance processes, with the adoption of the applicable measures. All occurrences were reviewed by the Ethics Committee, reported to the Audit and Risks Committee and resulted in the adoption of disciplinary measures and preventive actions, in compliance with internal policies. The proportion of substantiated cases remained stable compared to the same period of the previous year, indicating consistency in the processes for investigating and handling reports. The period was also marked by ISA ENERGIA BRASIL’s recognition as a 2025–2026 Pro-Ethics Company, the country’s leading initiative to promote corporate integrity, conducted by the Office of the Comptroller General (“CGU”), reinforcing the Company’s commitment to ethics, transparency and best corporate governance practices. ¹ Confirmed reports are those analyzed and deemed to be true. Environmental Compliance The Company did not record any significant fines for environmental non -compliance during the period and received four notices of violation, for which it submitted defenses demonstrating the regularity of its actions and the absence of violation. ¹ Significant fine: sanctions for environmental non-compliance exceeding US$10 thousand.
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24 ri@brasil.isaenergia.com SUBSEQUENT EVENTS 23rd Debenture Issuance On July 16, 2026, the Company concluded the fundraising through the 23 rd issuance of simple debentures, not convertible into shares, in the total amount of R$ 1.5 billion, in a single series, with a 4 -year term and cost of CDI +0.42% per year. The proceeds raised were fully allocated to replenish the Company’s cash position. Access the link for more information. Primary Public Offering of Shares (ISAE4) On July 15, 2026, the Company informed the market about the subsequent public offering (“Follow-on”) for the primary distribution of initially 22.2 million new preferred shares (“ISAE4”). The number of shares initially offered could be increased, at the issuer’s discretion, in agreement with the offering coordinators, by up to 22.2 million preferred shares. The offer was priced on July 23, when 44.4 million preferred shares were issued at a unit price of R$ 27.00. Settlement took place on July 28. To access the offering documents, click here and here. 24th Debenture Issuance On July 23, 2026, the Company closed the 24th issuance of simple debentures, not convertible into shares, to raise R$ 1.0 billion, in a single series, with a 4.5 -year term and cost of CDI +0.42% per year. Upon settlement, the proceeds will be fully allocated to R&I investments. Access the link for more information. Unwinding of Cross-Shareholdings in IE Madeira and IE Garanhuns On July 31, 2026, ISA ENERGIA BRASIL concluded the unwinding of cross-shareholdings involving its equity interests in the concessionaires IE Madeira and IE Garanhuns, a transaction disclosed to the market in the material fact published on March 19, 2026. With the completion of the transaction, the Company now holds 100% of IE Madeira, the concessionaire responsible for 2,385 km of direct current transmission lines, which has AAR (ex-PA) net of PIS/COFINS of R$ 796.7 million for the 2026/2027 cycle, and no longer holds an interest in IE Garanhuns, which has 633 km of transmission lines and AAR (ex-PA) net of PIS/COFINS totaling R$ 165.3 million for the same cycle. Following completion of the transaction, after the fulfillment of the conditions precedent and the payment of a cash adjust ment of R$ 1.2 billion to AXIA, IE Madeira’s results will be fully consolidated by the Company as of August 2026. For more information, please refer to the material fact.
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25 ri@brasil.isaenergia.com OTHER RELEVANT INFORMATION Periodic Tariff Review (PRT) – New Concessions 2026 PTR – New Concessions In June 2026, Technical Note 2026/90 (click here ) was published, revising the AAR of transmission assets whose concessions are subject to a Periodic Tariff Review (PTR) in the tariff cycle beginning in July 2026, including Concession Contract No. 005/2021 (IE Riacho Grande). The real economic repositioning index was +5.27%, resulting in a positive impact of R$ 4.9 million in absolute terms. Considering the 4.72% IPCA inflation rate for the period, the nominal repositioning index reached 10.25%. Company Current (Jun/25) (A) Reviewed (jun/26) Chg (R$) Nominal Real (B) IE Riacho Grande 100% 005/2021 93.1 102.7 9.5 10.25% 5.27% 4.91 Total 93 103 10 10.25% 5.27% 4.91 Total Particp. ISA ENERGIA BRASIL 93.1 102.7 9.5 10.25% 5.27% 4.91 Particip. ISA ENERGIA BRASIL (%) Contract AAR (R$ million, ex-PA) Repositioning Index Impact on AAR (A x B) (R$ million) RTP 2026 New Concessions
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26 ri@brasil.isaenergia.com AAR 2026/2027 Cycle On June 22, 2026, Order No. 2,268 was published (click here), which established the AAR of ISA ENERGIA BRASIL and its subsidiaries and jointly controlled companies for the availability of the transmission facilities that comprise the Basic Grid and Other Transmission Facilities, for the 12-month Tariff Cycle covering the period from July 1, 2026 to June 30, 2027 (2026/2027 cycle). According to the Order, AAR¹ and the amounts corresponding to the PAs of the consolidated companies and jointly controlled companies, net of PIS/COFINS, became R$ 6,773 million, weighted by ISA ENERGIA BRASIL’s interest in the jointly controlled companies (base date June 2026). Excl uding the amounts corresponding to the PAs, consolidated AAR for the cycle is R$ 6,776 million. After the asset swap concluded on July 31, 2026, AAR for the cycle, excluding PA, totaled R$ 7,082.3 million. Of this amount, 53.7% represents AAR from the renewed Paulista Concession contract, including Retrofitting and Improvements (“R&M”), RBSE and the Operation and Maintenance (“O&M”) portion of the contract. In addition, 46.3% of AAR refers to auctioned contracts from transmission auctions or acquisitions carried out by the Company, of which (i) 37.8% relates to projects in operation, i.e., with active AAR; and (ii) 8.4% relates to projects under construction, which will add remuneration to the Company when completed. ¹ AAR cycle 2026/2027 | ² Operation and Maintenance + Retrofitting and Improvements ¹ Based on the values established at the time of publication of the respective AAR Tariff Cycle Homologation Resolutions. AAR for the 2026/2027 cycle increased by R$ 708.9 million (+11.1%) compared to the previous tariff cycle (2025/2026). The main reasons for this variation are: ▲ incorporation of IE Madeira’s full AAR (+R$ 390.4 million); ▲ AAR inflation adjustment for the 2026/2027 cycle (+R$ 314.4 million); ▲ new R&I projects that started operations in the last cycle (+R$ 129.1 million); ▼ sale of interest in IE Garanhuns in August 2026 (-R$ 84,3 million). In addition, the resolution also defined the PA amounts to be offset in the same period to address any financial adjustments. Total PA, considering the consolidated total and the amount proportional to the Company’s interest in jointly controlled companies, varied by R$ 16.1 million for the 2026/2027 cycle. AAR Cycle¹ Evolution (million)
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27 ri@brasil.isaenergia.com The summary table of AAR for the 2026/2027 cycle is presented below. Amounts are net of PIS and COFINS, including regulatory charges for R&D, TFSEE and RGR, and exclude CDE and PROINFA charges. Parent Company AAR 25/26 Cycle AAR 26/27 Cycle PA AAR 26/27 Cycle REH 3.348 DSP 2268 Total with PA O&M 835 40 63 0 -16 921 984 835 10.4% R&M 813 38 60 0 -15 897 897 813 10.2% RBSE 1,899 90 0 0 -0 1,989 1,989 1,899 4.7% 012/2016 PBTE IPCA 235 11 0 0 0 246 -8 237 235 4.7% 002/2022 Piraquê IPCA 343 16 0 0 0 359.3 -4 355 343 4.7% Total Parent Company 4,125 195 123 0 -31 4,412 50 4,462 4,125 7% Subsidiárias Controladas AAR 25/26 Cycle AAR 26/27 Cycle PA AAR 26/27 Cycle REH 3.348 DSP 2268 Total with PA Subsidiaries (100%) in operation 875 41 6 5 -1 926 -21 905 875 6% IE Aguapeí 046/2017 Aguapeí IPCA 83 4 0 0 0 87 -3 84 83 5% IE Itaúnas 018/2017 Itaúnas IPCA 72 3 3 0 0 79 2 81 72 10% IE Itaquerê 027/2017 Itaquerê IPCA 71 3 0 0 0 74 -2 72 71 5% 004/2007 IEMG IPCA 15 1 0 0 0 16 -1 15 15 5% 007/2020 Triângulo Mineiro³ IPCA 46 2 3 0 0 51 1 52 46 10% IENNE 001/2008 IENNE IPCA 71 3 0 0 0 75 -2 73 71 5% IE Japi 026/2009 Serra do Japi IPCA 62 3 0 0 0 65 -1 64 62 5% IE Jaguar 9 015/2008 Getulina IPCA 77 4 0 0 0 81 -2 79 77 5% IE Biguaçu 012/2018 Biguaçu IPCA 56 3 0 0 0 59 -2 57 56 5% 143/2001 Botucatu-Xavantes IGP-M 21 0 0 0 -1 20 -1 20 21 -2% 042/2017 Bauru IPCA 16 1 0 0 0 17 -1 16 16 5% 026/2017 Tibagi IPCA 24 1 0 0 0 25 -1 24 24 5% 006/2020 Três lagoas IPCA 7 0 0 0 0 8 -0 8 7 5% 016/2008 Forquilinha IPCA 20 1 0 0 0 21 -1 21 20 5% 013/2008 Scharlau IPCA 9 0 0 0 0 9 -0 9 9 5% Evrecy 001/2020 Minuano IPCA 53 3 0 0 0 55 -3 52 53 5% 021/2018 Lorena IPCA 18 1 0 0 0 19 -1 19 18 5% 021/2011 Itapeti IPCA 9 0 0 0 0 10 -0 9 9 5% 012/2008 Piratininga IPCA 16 1 0 0 0 17 -0 16 16 5% 011/2022 Jacarandá IPCA 16 1 0 0 0 16.9 1 18 16 5% IE Pinheiros 018/2008 Atibaia II IPCA 9 0 0 0 0 9 -0 9 9 5% IE Tibagi 014/2023 Água Vermelha IPCA 8 0 0 0 0 8.9 0 9 8 5% IE Riacho Grande 005/2021 Riacho Grande IPCA 93 4 0 5 0 102.7 -3 100 93 10% Consolidated ISA ENERGIA BRASIL in operation 5,000 236 129 5 -32 5,338 29 5,367 5,000 7% Jointly Controlled Subsidiaries (equity income) AAR 25/26 AAR 26/27 PA AAR 26/27 REH 3.348 DSP 2268 Total with PA Subsidiaries (non-consolidated) in operation 1,588 75.1 0 0 0 1,664 -63 1,600 1,588 5% 013/2009 Lote D 408 19.3 0 0 0 427.7 -18 409.8 015/2009 Lote F 352 16.6 0 0 0 369.0 -15 353.6 IE Paraguaçu (50%) 003/2017 Paraguaçu IPCA 162 7.7 0 0 0 170 -6 164 162 5% IE Garanhuns (51%) 022/2011 Garanhuns IPCA 158 7.5 0 0 0 165.3 -6 159 158 5% IE Aimorés (50%) 004/2017 Aimorés IPCA 109 5.1 0 0 0 114 -4 110 109 5% IE Ivaí (50%) 022/2017 Ivaí IPCA 399 18.8 0 0 0 418 -14 403 399 0% Participation ISA ENERGIA BRASIL 803 38 0 0 0 841 -32 809 803 5% Participation ISA ENERGIA BRASIL - after assets' unwiding 803 52 0 0 0 1,147 -29 1,102 803 43% ISA ENERGIA BRASIL in operation 5,803 274 129 5 -32 6,179 -3 6,176 5,803 6% ISA ENERGIA BRASIL Total in operation after assets' unwiding 5,803 287 129 5 -32 6,485 0 6,469 803 707% Project Under Construction REH 3.348 DSP 2268 PA DSP 2268 834.536 921.2046 Total with PA Parent Company Under Construction 570 27 0 0 0 597 0 597 570 5% 006/2023 Serra Dourada IPCA 322 15 0 0 0 337 0 337 322 5% 012/2023 Itatiaia IPCA 248 12 0 0 0 260 0 260 248 5% ISA ENERGIA BRASIL under construction 570 27 0 0 0 597 0 597 570 5% ISA ENERGIA BRASIL TOTAL (Operational+ Construction) 6,373 301 129 5 -32 6,776 -3 6,773 6,373 6% ISA ENERGIA BRASIL TOTAL (Operational+ Construction) - after assets' unwiding 6,373 314 129 5 -32 7,082 0 7,066 6,373 11% IE Madeira (51%) IPCA RTP Others AAR 25/26 Cycle Var % ex-PA ISA ENERGIA BRASIL RTP Others AAR 25/26 Cycle Var % ex-PA Concessionaire Contract Project Index Inflation R&I Concessionaire Contract Project Index Inflation IE SUL IE Itapura IE Jaguar 8 R&I IE Jaguar 6 IE Tigabi IEMG Concessionaire (R$ million) Contract Project Index Inflation R&I RTP Others² AAR 25/26 Cycle Var % ex-PA ISA ENERGIA BRASIL 059/2001 IPCA 63 R&I RTP Others¹ AAR 25/26 Cycle Var % ex-PAInflationConcessionaire Contract Project Index
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28 ri@brasil.isaenergia.com Paulista Concession Renewal - Contract 059/2001 (RBNI/RBSE) The Extraordinary Shareholders Meeting held on December 3, 2012, unanimously approved extending concession agreement 059/2001, pursuant to Law 12,783/2013, and the concession was extended to December 2042, guaranteeing the Company the right to receive the amounts relating to the NI (*) and SE (**) assets. The amounts related to NI assets, of R$2,891,291 as per Interministerial Ordinance 580, were received between 2013 and 2015 (note 511.2 to the 4Q23 financial statements). In 2016, ANEEL issued Technical Note No. 336/2016, which presented a proposal for regulation as provided in MME Ordinance No. 120/2016 regarding the methodology for calculating the cost of capital (Ke) and the calculation of AAR, and determines the values of SE and payment terms for the concessionaires. On May 30, 2017, ANEEL Ruling No. 1,484/17 was issued, recognizing as the value of these assets the total of R$4,094,440, as of December 31, 2012. According to the accounting meth odology under the IFRS model, the initial impact of RBSE values was recognized in September 2016, and the additional amount recognized by ANEEL was recorded in the second quarter of 2017. These are presented as “Concession Assets” (note 5.1 of the financial statements for 4Q24). Technical Note No. 108/2020 – SGT/ANEEL, dated June 25, 2020, recalculated the AAR values starting from the 2020/2021 cycle, including the capital cost remuneration component (Ke), and implemented the effects of revoking injunctions that previously prevented the payment of Ke. These values were incorporated into the RTP calculations and approved by ANEEL's Board of Directors through Homologation Resolution No. 2,714/2020. Currently, there are two active injunctions. On April 22, 2021, ANEEL ruled in favor of the administrative appeal filed by the Company against Homologation Resolution No. 2,714/2020, which sought the right to retroactively update the RBSE values, and applied the restructuring of the RBSE financial component in accordance with Technical Note No. 068/2021 (note 1.2a of the financial statements for 4Q24). The premises valid as of the 2021/2022 cycle are: (i) conclusion of RBSE payments in 2028; (ii) reduced amortization of RBSE receivables during the 202 1/2022 and 2022/2023 cycles; and (iii) remuneration based on the regulatory WACC established in the 2018 RTP. From the 2023/2024 cycle onward, the payment flows projected by ANEEL returned to levels similar to those approved in Homologation Resolution No. 2,714/2020. After the ratification of the RTP results for the Transmission Operators (ReH 2,851/21), which included the rescheduling of RBSE’s financial component receipts, ABIAPE/ABRACE/ESBR filed a request for reconsideration, after it became final, questioning the calculation of the RBSE’s financial component and the rescheduling itself. In June 2021, the ANEEL General Tariff Superintendence (“SGT”) published NT 117/2021 and issued a public statement explaining that there were no calculation or methodological errors . However, in June 2022, the SGT of ANEEL issued Technical Note No. 85/2022, analyzing the requests for reconsideration concerning the payment of the financial component and the rescheduling of RBSE. That same month, a monocratic decision (Order No. 1,762/2022) was issued by an ANEEL director regarding the subject. After a collective decision by ANEEL’s board, the monocratic decision was suspended. In April 2023, the SGT published a new technical note (85/2023), addressing the comments on NT 085/2022 and Circular Letter No. 23/2022, dated August 16, 2022. At a board meeting held on June 10, 2025, the Brazilian Electricity Regulatory Agency (“ANEEL”) decided on the appeal filed by market agents concerning Homologation Resolution 2,851/21, related to the calculations for the payment of the RBSE (Rede Básica Sistema Existente) financial component. With this, the administrative discussion on the matter was closed. The board voted to partially apply the recommendations proposed in Technical Note 85/2023 (“NT85”) and decided to: (i) maintain the post -paid calculation methodology; (ii) create a new payment profile with separation into two flows; and (iii) update the WACC at each Periodic Tariff Review. In addition to the administrative discussion concluded in June 2025, Process No. TC 012.715/2017 -4 is pending before the Federal Court of Accounts (“TCU”). Its purpose is to evaluate the compliance and transparency of the methodology for defining the value of transmission assets existing as of 05/31/2000, but not yet amortized, as well as the methodology for updating and passing these values onto electricity tariffs, which is still under review. On 07/05/2023, the Public Prosecutor’s Office at the TCU (MPTC U) stated it was in favor of ISA ENERGIA BRASIL joining as an interested party and concluded that the regulatory option of the MME should be respected by the TCU. Subsequently, at the session held on May 6, 2026, TCU unanimously decided to dismiss the aforementioned proceeding. In addition, the matter is subject to judicial proceedings. As of June 30, 2026, there were 40 (forty) ongoing lawsuits filed by industry entities, which discuss the legality of MME Ordinance No. 120/2016. The first -instance decisions recognized the legality of MME Ordinance No. 120/2016 and the payment method established therein and, therefore, were favorable to the concessionaires. However, they are subject to reversal by higher courts and, in this regard, on May 26, 2026, the 7 th Panel of the Federal Regional Court of the 1 st Region (TRF1) ruled on the appeals in five of the
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29 ri@brasil.isaenergia.com forty aforementioned lawsuits and decided to recognize the legality of incorporating RBSE assets into the Regulatory Remuneration Base and to declare the nullity of paragraph 3 of article 1 of MME Ordinance No. 120/2016. Such decisions are subject to appeals before higher courts. It is not possible to rule out the possibility of new lawsuits related to this matter, nor can the possibility of new judicia l decisions altering one or more conditions of the RBSE payment be disregarded. Any new judicial decisions, depending on their cont ent and scope, if not reversed in a timely manner, may or may not have significant impacts on the Company’s receipts, potentially requiring, as the case may be, a reassessment of investment plans, dividend distribution, and corporate strategy, in addition to the regular accounting records of such impacts. Considering ANEEL’s decision at the Board of Directors meeting held on June 10, 2025, and based on the tariff adjustment for the 2026/2027 cycle, below is the payment flow of the amounts due related to the renewal of the Paulista Concession: RBSE Receivable flow after ANEELs Decision in 2025 1 2 3 4 1 Real values, base date June 2026, based on the spreadsheets published at the closing of Public Consultation No. 12/2024. 2 Excludes the CAIMI portion and Other Revenue from RBSE AAR. 3 The movement of the asset base comprising RBSE should gradually reduce the AAR portion related to the economic component, and after the 2033/2034 cycle, only the amount related to capital remuneration for land and warehouse inventory will remain until the end o f the concession, in 2042. 4 The expected flow from the 2028/2029 to 2032/2033 cycles was estimated based on the appraisal report and the assumptions defined in the 2023 RTP. The amounts will be reassessed in the 2028 tariff review process. (*) NI – facilities energized as of June 1, 2000 (**) SE – facilities related to non-depreciated assets existing as of May 31, 2000. Supplementary Retirement Plan – Law 4,819/58 The supplementary retirement plan is governed by State Law 4,819/58 and applies to employees hired prior to May 13, 1974, by government agencies and corporations in which the state of São Paulo is the controlling shareholder and exercises control. The funds needed to meet the costs under this plan are the responsibility of the São Paulo State Government and the plan was implemented as per the agreement between the Tax Authority of the State of São Paulo (“ SEFAZ”) and the Company on December 10, 1999. Payments of the supplementary retirement benefits were made monthly by SEFAZ, which transferred the amount to be paid to ISA ENERGIA BRASIL, which then transferred it to “Fundação CESP” to be paid to individual retirees. Since January 2004, retiree benefits have been processed directly by SEFAZ. This change in the process revealed disallowances such as payments above the cap (equivalent to the State Governor’s salary). As a result, SEFAZ started excluding the surplus amounts from the benefits paid to retirees. Public -Interest Civil Action and Class Action In June 2005, after the courts dismissed a claim, the Funcesp Retirees Association (AAFC) obtained an injunction in the Labor Court, which ordered the maintenance of the previous payment in full. The benefits payment process has since reverted to the original model, where “Fundação CESP” was responsible for retirement payments. However, SEFAZ
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30 ri@brasil.isaenergia.com continues to transfer the adjusted amount to ISA ENERGIA BRASIL, which then adds to the difference so that retirement payments are made in full, as ordered by the injunction. Collection Lawsuit Since 2005, SEFAZ has transferred to the Company an amount lower than that required to fully cover retirement benefit payments (approximately 70%), as a re xsult of a preliminary injunction issued by the 49th Labor Court. ISA ENERGIA BRASIL has therefore been supplementing the remaining portion (approximately 30%) to ensure the full payment of retirement benefits. This supplementation made by the Company is be ing claimed through a collection lawsuit against SEFAZ. This collection action was decided in favor of the Company at the second instance. In August 2017, SEFAZ filed a Special Appeal with the Superior Court of Justice (“STJ”), which is still pending admissibility analysis. As of March 31, 2026, the amount recorded on the Company’s balance sheet totaled approximately R$ 2. 8 billion, net of the provision for credit losses, recorded in 2013. Between August 2018 and March 2019, ISA ENERGIA BRASIL received full transfers from SEFAZ pursuant to a court injunction, which was subsequently suspended by the STJ pending judgment of SEFAZ’s appeal. SEFAZ’s appeal was decided monocratically by the STJ in March 2024, determining the return of the case to the São Paulo State Court of Justice (“TJSP”), which is expected to define, in its decision, the responsibility of each party with respect to the comp onents and items that make up the retirement benefit supplements. The continuation of the payments of the disallowed amounts by ISA ENERGIA BRASIL (as has occurred since 2005) was determined until the final and unappealable decision of the case. In October 2024, by agreement of the parties for the purpose of attempting an amicable settlement, the STJ suspended the proceedings of the collection action for 180 days. On May 22, 2025, a mediation opening hearing was held at the Judicial Center for Con flict Resolution of the STJ (“CEJUSC/STJ”), with the participation of the Office of the Attorney General of the State of São Paulo, at which time the suspension period was extended for an additional 180 days. In addition to the opening hearing, six hearings were held between August and November 2025. In 2026, three mediation hearings were held on February 3, April 4 and June 16, and a new hearing was scheduled for August 26. In addition, in February 2026, the suspension period of the proceedings was renewed for another 180 days. On June 16, 2026, the suspension of the proceeding was renewed for an additional 180 days. The attempt at an amicable settlement does not prejudice the Company’s rights and does not alter any court decision currently in force or the current payment flow. If the settlement attempt is unsuccessful, the proceeding will resume its previous course. The Company continues its efforts to maintain the favorable merits decision obtained before the São Paulo State Court of Justice. The amount recorded by the Company under “Amounts receivable - Department of Finance” totaled R$ 2,829.5 million as of June 30, 2026. Additionally, the Company has a provision of R$ 516.3 million recorded in 2013 due to the extended timeframe expected for the realization of part of the receivables from the State of São Paulo and procedural developments that occurred at that time. It should be noted that the amounts mentioned above are historical and their accounting recognition does not consider any type of correction or update.
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31 ri@brasil.isaenergia.com GLOSSARY ADTV (Average Daily Traded Volume) - Average daily traded volume. ANEEL (Brazilian Electricity Regulatory Agency) - Government agency responsible for regulating and supervising the generation, transmission, distribution and commercialization of electricity in Brazil, ensuring the quality of the service provided, equal treatment of users and control over the reasonableness of tariffs charged to consumers, while preserving the economic and financial viability of market agents and the industry. ANEEL supervises and regulates access to transmission systems and establishes the tariffs related to such systems, with TUST being the tariff charged for the use of the Basic Grid and Other Transmission Facilities – DIT. CAAE (Annual Cost of Electricity Assets) - Revenue from investments in assets. It consists of capital remuneration and the regulatory reintegration quota (“QRR”). CAGR (Compound Annual Growth Rate) - Compound annual growth rate. CAOM (Administration, Operation and Maintenance Costs) - Portion of revenue that may be divided into: (i) O&M revenue, intended to cover costs and expenses such as salaries, maintenance expenses and others; and (ii) revenue to cover the costs of movable and immovable facilities (“CAIMI”). CCEE (Electricity Trading Chamber) - Operates under authorization from the Granting Authority and under ANEEL regulation and supervision, with the purpose of enabling electricity purchase and sale transactions among CCEE agents. CDE (Energy Development Account) - Regulatory charge to promote universal access to electricity services and subsidize low-income consumers. Organic growth - Growth through investments in retrofitting and improvements. CVM (Brazilian Securities and Exchange Commission) – government agency linked to the Ministry of Finance, responsible for supervising, regulating, disciplining and developing the securities market in Brazil. EBITDA ( Earnings Before Interest, Taxes, Depreciation & Amortization ) - Earnings before interest, taxes, depreciation and amortization. Regulatory charges – Amounts collected by transmission companies and passed through to CCEE, ANEEL and MME and/or invested in R&D projects. They have a neutral effect on the transmission company. Energization - Start of operation of a project, whether retrofitting, improvement or greenfield. DIT (Other Transmission Facilities) - facilities that are not part of the Basic Grid, generally because they operate at voltages below 230 kV or serve specific purposes. Greenfield - growth projects awarded through auctions and built from scratch. IBBC (Bovespa BR+ Cap 5% Index B3) - indicator of the average performance of the prices of assets with the highest tradability and representativeness. Its name “Cap 5%” indicates that the maximum weight of a single asset in the portfolio is 5%. It is composed of both Brazilian shares and BDRs of companies whose primary listing is in the United States. IBBE (Bovespa BR+ Equal Weight Index B3) - Brazilian stock exchange index that seeks to reflect the average performance of a set of shares with equal weight, instead of the market capitalization weighting usually used in the traditional Ibovespa. Its objective is to provide a less concentrated view of the market, where the performance of large companies does not distort the overall performance of the index as much. IBBR (Bovespa B3 BR+ Index) - indicator of the average performance of the prices of assets with the highest tradability and representativeness. Composed of shares, units and BDRs of Brazilian companies. IBEP (Bovespa B3 Private Companies Index) - indicator of the average performance of the assets with the highest tradability and representativeness and that have private controlling shareholders. IBEW (Bovespa B3 Equal Weight Index) - indicator of the average performance of the assets that comprise the Ibovespa, assigning equal weight to each share in the index composition. IBOV B3 (Bovespa Index B3) - main performance indicator for shares traded on B3, comprising the most important companies in the Brazilian capital market. It is composed of shares that represent 85% in descending order of Tradability
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32 ri@brasil.isaenergia.com Index (“IN”) (90% buffer); 95% trading session presence; 0.1% of financial volume in the cash market (standard lot); and are not penny stocks. IBRA (Broad Brazil Index) - indicator of the average performance of all assets traded in B3’s cash market (standard lot) that meet minimum liquidity and trading session presence criteria, providing a broad view of the stock market. IBRX100 (Brazil 100 Index) - indicator of the average performance of the prices of the 100 assets with the highest tradability and representativeness in the Brazilian equity market. IBSD (Bovespa Smart Dividend Index) - indicator of the average performance of assets of listed companies that stand out in terms of investor remuneration through the distribution of dividends and interest on equity. IBVL (Bovespa Smart Low Volatility Index B3) - indicator of the average performance of the assets with the highest tradability, representativeness and lower volatility in daily returns. ICO2 (Efficient Carbon Index) - companies’ adherence to B3’s ICO2 demonstrates their commitment to efficiency in Greenhouse Gas (“GHG”) emissions and to the adoption of management practices that lead to greater efficiency in such emissions, contributing to the transition toward a low-carbon economy. IDIV (Dividend Index) - average performance of the prices of assets that stood out in terms of investor remuneration through dividends and interest on equity. IE - Electric Interconnection. IEE (Electric Energy Index) - B3 sector index designed to measure the performance of the electric energy sector. IENS (Non -Supplied Energy Index) - energy index that measures the energy not consumed as a result of an interruption. IGC (Corporate Governance Index) – indicator of the average performance of the prices of assets issued by companies listed on B3’s Novo Mercado or Level 1 or Level 2 segments. IGCT (Corporate Governance Trade Index) - indicator of the average performance of the prices of assets issued by companies that are part of the IGC. IPCA (Broad Consumer Price Index) - measures inflation for a basket of products sold in wholesale and retail markets. ISE B3 (Corporate Sustainability Index) - indicator of the average performance of the prices of assets issued by companies selected for their recognized commitment to corporate sustainability. JCP (Interest on Equity) – type of remuneration that a company may distribute to its shareholders, partners or quotaholders. Energy Transmission Auctions - bidding processes established by MME and ANEEL to grant concessions for transmission lines and substations in Brazil. M&A (Mergers and Acquisitions) - Mergers and acquisitions. Improvement - comprises the installation, replacement or refurbishment of equipment in existing transmission facilities, or the adequacy of such facilities, aimed at maintaining the regularity, continuity, safety and modernization of the public electricity transmission service. MLCX (MidLarge Cap Index) - average performance of the assets of the companies with the largest market capitalization on B3. MME – Ministry of Mines and Energy. O&M - Operation and Maintenance. ONS (National Electric System Operator) - Entity responsible for carrying out the coordination and control activities for the operation of electricity generation and transmission in the SIN. Other Revenue - Revenue earned from activities outside the concession, partially allocated to support tariff affordability. PA (Adjustment Portion) - Offsets the surplus or deficit in collection in the period prior to the tariff adjustment. PMSO - Personnel, Materials, Services and Others.
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33 ri@brasil.isaenergia.com PROINFA - Incentive Program for Alternative Electricity Sources, a regulatory charge used to subsidize alternative energy sources. PV (Variable Portion) - Penalizes asset revenue due to unavailability. R&D – Research and Development. AAR (Annual Allowed Revenue ) - Remuneration that transmission companies receive for providing public transmission services to users. For transmission companies awarded through auctions, AAR is determined as a result of the transmission auction itself and is paid to transmission companies as of the commercial operation date of their facilities, with reviews every four or five years, pursuant to the concession agreements. For transmission comp anies whose concession agreements were renewed, AAR was calculated based on Operation and Maintenance costs, as established by Law 12,783, dated January 11, 2013. In cases where studies indicate the need for retrofitting in the transmission concession, ANEEL calculates an additional AAR amount to remunerate the new facilities, always through an Authorizing Resolution. RB (Basic Grid) - SIN transmission facilities owned by public transmission service concessionaires, defined according to the criteria established in ANEEL regulations. RBNI (New Investments Basic Grid) - Portion of revenue (AAR) corresponding to new facilities comprising the Basic Grid, authorized and with revenues established by a specific resolution. RBSE (Existing System Basic Grid) - Portion of AAR corresponding to the facilities comprising the Basic Grid, as defined in the Annex to Resolution No. 166, dated May 31, 2000. Retrofitting - Installation, replacement or refurbishment of equipment in existing transmission facilities, or the adequacy of such facilities, aimed at increasing transmission capacity, increasing the reliability of the National Interconnected System, extending useful life or connecting users, as recommended by transmission system expansion plans. RGR - Global Reversion Reserve. SIN (National Interconnected System) – Set of facilities and equipment that enables the supply of electricity in the electrically interconnected regions of the country, in accordance with applicable regulation. TCU - Federal Court of Accounts. TFSEE - Electricity Services Inspection Fee. TUST (Tariff for the Use of the Electricity Transmission System) – Tariff paid by distribution companies, generators, and free and special consumers for the use of the Basic Grid and DIT and adjusted annually according to (i) inflation; and (ii) new revenues corresponding to energized projects. UTIL B3 (Public Utilities Index) - indicator of the average performance of the prices of the most tradable and representative assets in the public utilities sector (electricity, water and sanitation, and gas).
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34 ri@brasil.isaenergia.com ATTACHMENTS Attachment I – Greenfield Projects since 2016 | Growth Clique aqui para acessar a planilha. Paraguaçú (Lot 3) 003/2017 IE Paraguaçu 50% BA/MG 85.0 fev-22 jan-19 254.8 333.4 ✓ 2Q19 100% 100% 3Q22 Aimorés (Lot 4) 004/2017 IE Aimorés 50% MG 57.0 fev-22 jan-19 170.6 197.5 ✓ 2Q19 100% 100% 2Q22 Itaúnas (Lot 21) 018/2017 IE Itaúnas 100% ES 79.0 jun-22 jul-18 297.8 373.8 ✓ 3Q18 100% 100% 4Q23 Ivaí² (Lot 1) 022/2017 IE Ivaí 50% PR 208.8 ago-22 fev-21 968.2 1,064.4 ✓ 4Q19 100% 100% 4Q22 Tibagi (Lot 5) 026/2017 IE Tibagi 100% SP / PR 24.8 ago-21 jan-17 134.6 117.5 ✓ 3Q18 100% 100% 4Q20 Itaquerê (Lot 6) 027/2017 IE Itaquerê 100% SP / PR 74.1 ago-21 jun-18 397.7 255.9 ✓ 3Q18 100% 100% 3Q20 Aguapeí (Lot 29) 046/2017 IE Aguapeí 100% SP / PR 87.2 ago-21 dez-18 601.9 363.4 ✓ 3Q19 100% 100% 1Q21 Bauru (Lot 25) 042/2017 IE Jaguar 6 100% SP 16.9 fev-21 ago-19 125.8 63.0 ✓ 2Q18 100% 100% 3Q19 Lorena (Lot 10) 021/2018 IE Itapura 100% SP 19.2 set-22 jan-20 237.9 126.1 ✓ 3Q19 100% 100% 4Q21 Biguaçu (Lot 1) 012/2018 IE Biguaçu 100% SC 58.9 set-23 set-21 641.4 456.0 ✓ 1Q21 100% 100% 3Q22 Minuano (Lot 1) 6 001/2020 Evrecy 100% RS 55.5 mar-25 jan-20 681.6 737.6 ✓ 1Q22 100% 100% 4Q24 Três Lagoas (Lot 6) 006/2020 IE Tibagi 100% MS / SP 7.8 set-23 jan-20 98.8 87.1 ✓ 2Q21 100% 100% 2Q22 Triângulo Mineiro 007/2020 IEMG 100% MG 50.9 mar-25 jan-20 553.6 519.6 ✓ 1Q22 100% 100% 3Q23 001/2020 (dec/2020) Riacho Grande (Lot 7) 005/2021 IE Riacho Grande 100% SP 102.7 mar-26 jan-26 1,140.6 922.1 ✓ 4Q23 100% 100% 4T25 Piraquê (Lot 3) 008/2022 ISA ENERGIA BRASIL 100% MG / ES 359.3 set-27 jan-26 3,653.6 3,866.1 ✓ 3T24 100% 100% 1Q26 Jacarandá (Lot 6) 011/2022 IE Jaguar 8 100% SP 16.9 mar-26 mar-26 232.3 189.3 ✓ 3T24 100% 100% 1Q26 Serra Dourada (Lot 1) 006/2023 ISA ENERGIA BRASIL 100% BA/MG 337.0 mar-29 immediate 3,157.0 1,790.5 ü 3T25 96% 49% - Itatiaia (Lot 7) 012/2023 ISA ENERGIA BRASIL 100% RJ/MG 259.9 mar-29 immediate 2,300.6 533.4 3T26 3T26 89% 33% - Água Vermelha (Lot 9) 014/2023 IE Tibagi 100% SP 8.9 set-26 Imediata 94.2 87.1 ✓ 3T24 100% 100% 2Q25 1,909.7 15,742.9 12,083.7 Entry in Commercial Operation 013/2015 (oct/2016) 005/2016 (apr/2017) 002/2018 (jun/2018) 002/2019 (dec/2019) Land Development4 Projects Development5Project Deadline ANEEL Total (19) Initiation of Construction RAP ISA ENERGIA BRASIL Cycle 2026/20267 (R$ million) Necessity Date¹ Environment al License (LI) Auctions Company % ISA ENERGIA BRASIL UF ANEEL CAPEX ISA ENERGIA BRASIL Participation (R$ million) 001/2022 (jun/2022) Contract Total CapEx ISA ENERGIA BRASIL until 06/30/2026 (R$ million) 001/2023 (jun/2023)
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35 ri@brasil.isaenergia.com Annex II – Investments in Projects Note: Considers ISA ENERGIA BRASIL’s proportional interest in non-consolidated companies (subsidiaries under shared control). Investments (R$ Million) 2Q26 2Q25 Chg (% ) Retroffiting Projects 445.4 379.3 17.4% Greenfield Projects 608.1 722.8 -15.9% 100% ISA ENERGIA BRASIL 607.8 722.8 -15.9% Piraquê 84.4 538.0 -84.3% Riacho Grande 0.0 77.1 -100.0% Serra Dourada 455.8 48.8 834.1% Água Vermelha 0.0 16.0 -100.0% Itatiaia 52.2 19.7 164.7% Jacarandá 13.5 23.1 -41.5% Minuano 1.9 0.0 N.A Jointly-controlled subsidiaries 0.2 0.0 N.A Ivaí 0.2 0.0 N.A Total 1,053.5 1,102.1 -4.4% Consolidated + Jointly-controlled
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36 ri@brasil.isaenergia.com Annex III – Regulatory Balance Sheet Assets (R$ thousand) 30/06/2026 30/06/2025 CURRENT Cash and Cash Equivalents 468,699 1,356,062 Financial Investments 1,288,565 808,924 Accounts receivable - Concessionaires and 456,479 469,745 Inventory 54,679 48,054 Recoverable taxes and contributions 322,473 229,311 Derivative instruments 0 37,384 Credit with controlled parties 84,799 126,061 Prepaid Expenses 62,557 6,061 Restricted cash 0 0 Others 164,965 165,619 2,903,216 3,247,221 NON-CURRENT Long-Term Assets Restricted cash 20,071 18,888 Accounts receivable - Concessionaires and 159,267 205,383 Accounts Receivable from the State Finance 2,829,539 2,760,806 Deferred income taxes and social contribution 0 0 Pledges and Escrow 46,317 46,049 Derivative financial instruments 35,026 20,406 Others 94,562 76,525 3,184,782 3,128,057 Investments 1,395,576 1,366,474 Imobilized 22,687,269 20,832,086 Intangible 1,812,433 1,819,316 25,895,278 24,017,876 29,080,060 27,145,933 Total Assets 31,983,276 30,393,154 Consolidated
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37 ri@brasil.isaenergia.com Liabilities and Shareholders' Equity (R$ thousand) 30/06/2026 30/06/2025 CURRENT Loans and Financing 92,069 90,082 Debentures 350,737 496,001 Leasing 17,140 18,677 Derivative financial instruments 5,443 2,916 Suppliers 229,979 254,342 Taxes and social charges to be collected 296,085 213,752 Deferred Income Tax and Social Contribution 0 0 Regulatory charges to be collected 33,001 66,723 Interest on Shareholders' Equity / Dividends to 12,484 422,540 Provisions 80,601 79,962 Amounts Payable - Funcesp 942 1,335 Capex - Provisions 226,118 210,460 Others 14,457 30,299 1,359,056 1,887,089 NON-CURRENT Long-Term Liabilities Loans and Financing 642,406 669,117 Debentures 16,592,622 14,696,513 Leasing 30,725 36,959 Derivative financial instruments 1,225 17,312 Suppliers 3,861 3,456 Diferred PIS and COFINS 23,165 25,773 Deferred income taxes and social contribution 1,455,352 1,524,834 Regulatory charges to be collected 43,843 35,404 Provisions 162,726 157,457 Obligations connected to concession service 900,615 850,307 Others 396 334 19,856,936 18,017,466 SHAREHOLDER'S EQUITY Share Capital 3,590,020 3,590,020 Capital Reserves 666 666 Income Reserves 4,070,802 3,742,461 Revaluation reserve 2,415,437 2,493,015 Other Comprehensive Results 89,530 97,571 Additional Dividends Proposed 279,322 279,322 10,445,777 10,203,055 Non-controlling shareholders' share of investment funds 321,507 285,544 10,767,284 10,488,599 Total Liabilities and Shareholders' Equity 31,983,276 30,393,154 Consolidated
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38 ri@brasil.isaenergia.com Annex IV – Regulatory Income Statement ¹ Inclui custos e despesas com Entidade de Previdência Privada Income Statement (R$ thousand) 2Q26 2Q25 Chg (% ) 1H26 1H25 Chg (% ) Gross Revenue 1,421,167 1,174,144 21.0% 2,814,646 2,468,120 14.0% Availability of Electric Network 1,411,383 1,163,603 21.3% 2,793,167 2,445,424 14.2% Others 9,784 10,541 -7.2% 21,479 22,696 -5.4% Deductions from the Operational Revenue -177,793 -145,513 22.2% -345,008 -307,637 12.1% T axes and Contributions on Revenue -122,326 -101,351 20.7% -242,485 -213,887 13.4% Regulatory charges -55,467 -44,162 25.6% -102,523 -93,750 9.4% Net Revenue 1,243,374 1,028,631 20.9% 2,469,638 2,160,483 14.3% Costs and Operational Expenses -436,651 -421,230 3.7% -785,860 -808,803 -2.8% Personnel -110,278 -103,937 6.1% -218,052 -213,914 1.9% Material -7,246 -7,104 2.0% -10,964 -11,223 -2.3% Services -62,797 -52,013 20.7% -107,936 -91,954 17.4% Depreciation -222,070 -215,793 2.9% -391,582 -423,781 -7.6% Others -34,261 -42,383 -19.2% -57,326 -67,929 -15.6% Result of Service 806,723 607,401 32.8% 1,683,778 1,351,680 24.6% Financial Results -638,919 -351,730 81.7% -1,121,823 -703,118 59.5% Income from Financial Investments 63,249 72,948 -13.3% 120,325 153,361 -21.5% Result of Liquid Monetary Variation -285,397 -126,121 126.3% -450,928 -287,755 56.7% Asset and Liability Interest -23 -1,293 -98.2% 166 -2,815 n.a Interest/Charges on loans -397,092 -324,406 22.4% -778,756 -596,754 30.5% Others -19,656 27,142 n.a -12,630 30,845 n.a Operational Result 167,804 255,670 -34.4% 561,955 648,562 -13.4% Equity Income 79,271 91,505 -13.4% 163,055 166,618 -2.1% Other Operational Revenues/Expenses -61,901 -33,651 84.0% -87,292 -62,668 39.3% Results before Taxes 185,173 313,524 -40.9% 637,718 752,512 -15.3% Income Tax and Social Contribution on Income 3,444 -40,782 n.a -81,277 -130,946 -37.9% Current -52,332 11,308 n.a -135,500 -83,625 62.0% Deferred 55,776 -52,090 n.a 54,223 -47,321 n.a Consolidated Income/Losses of the Period with the Participation of the Non Controlling Shareholder 188,617 272,742 -30.8% 556,441 621,566 -10.5% Participation of Non Controlling Shareholder -14,752 -17,101 -13.7% -24,841 -28,572 -13.1% Net Income/Loss Consolidated in the Period 173,865 255,641 -32.0% 531,600 592,994 -10.4% Consolidated
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39 ri@brasil.isaenergia.com Annex V – Indirect Cash Flow – Regulatory¹ ¹ The indirect cash flow recorded under the regulatory methodology considers cash outflows related to greenfield, brownfield, a nd Retrofitting and Improvements projects as investment flows. Cash Flow of operational activities (R$ thousand) 1H26 1H25 Cash generated by operational activities 1,932,924 1,694,410 Net Income 556,441 621,566 Employee benefit - actuarial deficit 2,707 0 Deferred PIS and COFINS -2,607 -8,306 Depreciation and amortization 436,861 467,194 Deferred income taxes and social contribution -55,456 47,320 Provision for Lawsuit Liabilities -2,120 -42,661 Residual value of fixed/intangible assets 33,951 20,881 Tax benefit - incorporated goodwill 19 18 Result of equity income -163,053 -166,618 Income from financial investments -33,335 -57,166 Interest and exchange variations on loans, financing and debentures 1,206,274 877,386 Interest and monetary and exchange variations on assets and liabilities 26 -40,288 Financial Instruments -21,942 3,655 Transactions with non-controlling shareholders -24,841 -28,572 Assets Variation -174,913 38,185 Restricted cash 0 0 Accounts receivable - Concessionaires and Permissionaires 59,382 80,675 Inventories -6,625 -5,732 Accounts Receivable from the State Finance Secretariat -68,733 -90,715 Recoverable taxes and contributions -84,680 73,103 Prepaid Expenses -56,496 -26,514 Pledges and Escrow 694 -73 Others -18,455 7,441 Liabilities Variation 51,586 -14,062 Suppliers -23,958 70,145 Taxes and social charges to be collected 168,242 193,939 Labor obligations 639 4,136 Tax payment -113,840 -82,747 Regulatory charges to be collected -25,897 -10,901 Provisions 224,651 -4,762 Amounts payable to Vivest -393 406 Global Reversal Reserve - RGR -1,240 -1,240 Obligations linked to the concession of the service 50,310 -7,646 Post-employment benefit - actuarial liability -20,597 0 Others -206,331 -175,392 Net cash generated in operational activities 1,809,597 1,718,533 Investments Activites Cash Flow -2,553,351 -2,624,965 Restricted cash -1,183 246 Financial Investments -1,763,999 -2,925,957 Redemptions of financial investments 1,353,656 2,484,460 Fixed Assets -2,317,405 -2,183,714 Received dividends 175,580 0 Cash used in financing activities -143,609 -1,354,741 New loans and debentures 4,789,453 1,446,492 Loan and debentures payments (principal) -3,698,909 -988,165 Loan and debentures payments (interest) -568,150 -508,518 Lease Payments (principal and interest) -11,973 -8,500 Derivative instruments 9,759 39,856 Paid dividends and interest on equity -663,789 -1,335,906 Net variation in Cash and Cash Equivalents -887,363 -2,261,173 Opening Balance of Cash and Cash Equivalents 1,356,062 2,914,747 Closing Balance of Cashand Cash Equivalents 468,699 653,574 Closing Balance of Cash and Cash Equivalents -887,363 -2,261,173 Consolidated
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40 ri@brasil.isaenergia.com Annex VI – Regulatory Result of Non-Consolidated Companies Income Statement (R$ thousand) Gross Operational Revenue 211,347 200,362 5.5% 422,670 392,781 7.6% Operational Revenue Deductions -29,214 -27,241 7.2% -57,746 -52,416 10.2% Net Operational Revenue 182,133 173,121 5.2% 364,924 340,365 7.2% Costs and Expenses -12,600 -15,686 -19.7% -33,891 -36,184 -6.3% Depreciation -36,425 -36,493 -0.2% -72,855 -73,383 -0.7% EBITDA 169,558 157,301 7.8% 331,063 304,064 8.9% Gross Profit 133,108 120,943 10.1% 258,178 230,798 11.9% Financial Result -8,526 -10,539 -19.1% -15,123 -26,765 -43.5% Other Revenues and Expenses 25 -134 n.a 30 -117 n.a Income before IR & CSLL 124,606 110,270 13.0% 243,085 203,917 19.2% IR & CSLL* -28,812 -21,129 36.4% -52,333 -41,706 25.5% Net Income 95,794 89,140 7.5% 190,752 162,211 17.6% ISA ENERGIA BRASIL Particip. (51% ) on EBITDA 86,474 80,224 7.8% 168,842 155,073 8.9% ISA ENERGIA BRASIL Particip. (51% ) on Net Income 48,855 45,461 7.5% 97,283 82,728 17.6% 2Q25 IE MADEIRA 2Q26 Chg (% ) 1H26 1H25 Chg (% ) Income Statement (R$ thousand) Gross Operational Revenue 42,834 41,537 3.1% 88,540 82,904 6.8% Operational Revenue Deductions -5,715 -5,491 4.1% -11,396 -10,913 4.4% Net Operational Revenue 37,119 36,046 3.0% 77,143 71,991 7.2% Costs and Expenses -3,788 -3,797 -0.3% -8,035 -8,181 -1.8% Depreciation -7,136 -6,355 12.3% -14,275 -12,712 12.3% EBITDA 33,331 32,249 3.4% 69,108 63,810 8.3% Gross Profit 26,195 25,894 1.2% 54,834 51,098 7.3% Financial Result 350 -167 n.a -309 -1,183 -73.9% Other Revenues and Expenses 0 0 -100.0% 0 0 -100.0% Income before IR & CSLL 26,544 25,727 3.2% 54,525 49,915 9.2% IR & CSLL* -1,584 -1,582 0.1% -3,128 -3,073 1.8% Net Income 24,960 24,145 3.4% 51,397 46,842 9.7% ISA ENERGIA BRASIL Particip. (51% ) on EBITDA 16,999 16,447 3.4% 35,245 32,543 8.3% ISA ENERGIA BRASIL Particip. (51% ) on Net Income 12,730 12,314 3.4% 26,212 23,890 9.7% IE GARANHUNS Chg (% )2Q26 2Q25 Chg (% ) 1H26 1H25 Income Statement (R$ thousand) Gross Operational Revenue 29,968 28,454 5.3% 59,936 56,909 5.3% Operational Revenue Deductions -3,017 -2,977 1.3% -6,132 -5,954 3.0% Net Operational Revenue 26,951 25,477 5.8% 53,804 50,955 5.6% Costs and Expenses -1,453 -1,698 -14.4% -2,743 -3,354 -18.2% Depreciation -2,722 -2,798 -2.7% -5,443 -5,442 0.0% EBITDA 25,498 23,779 7.2% 51,061 47,601 7.3% Gross Profit 22,776 20,981 8.6% 45,618 42,159 8.2% Financial Result -8,592 927 n.a -16,945 1,329 n.a Other Revenues and Expenses 0 0 N.A. 0 0 N.A. Income before IR & CSLL 14,184 21,908 -35.3% 28,673 43,488 -34.1% IR & CSLL* -1,280 -2,100 -39.0% -3,044 -4,614 -34.0% Net Income 12,904 19,808 -34.9% 25,629 38,874 -34.1% ISA ENERGIA BRASIL Particip. (50% ) on EBITDA 12,749 11,890 7.2% 25,531 23,801 7.3% ISA ENERGIA BRASIL Particip. (50% ) on Net Income 6,452 9,904 -34.9% 12,815 19,437 -34.1% IE AIMORÉS 2Q26 2Q25 Chg (% ) 1H26 1H25 Chg (% )
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41 ri@brasil.isaenergia.com Income Statement (R$ thousand) Gross Operational Revenue 44,728 42,384 5.5% 89,064 84,045 6.0% Operational Revenue Deductions -4,725 -4,718 0.1% -9,052 -9,365 -3.3% Net Operational Revenue 40,003 37,666 6.2% 80,012 74,680 7.1% Costs and Expenses -2,379 -2,189 8.7% -4,248 -4,368 -2.7% Depreciation -4,657 -4,732 -1.6% -9,315 -9,304 0.1% EBITDA 37,624 35,477 6.1% 75,764 70,312 7.8% Gross Profit 32,967 30,745 7.2% 66,449 61,008 8.9% Financial Result -15,246 2,244 n.a -30,555 3,706 n.a Other Revenues and Expenses 0 0 N.A. 0 0 N.A. Income before IR & CSLL 17,721 32,989 -46.3% 35,894 64,714 -44.5% IR & CSLL* 1,776 -2,620 n.a -657 -6,044 -89.1% Net Income 19,497 30,369 -35.8% 35,237 58,670 -39.9% ISA ENERGIA BRASIL Particip. (50% ) on EBITDA 18,812 17,739 6.1% 37,882 35,156 7.8% ISA ENERGIA BRASIL Particip. (50% ) on Net Income 9,749 15,185 -35.8% 17,619 29,335 -39.9% Chg (% ) IE PARAGUAÇU 1H26 1H25 Chg (% )2Q26 2Q25 Income Statement (R$ thousand) Gross Operational Revenue 109,767 104,217 5.3% 222,830 209,962 6.1% Operational Revenue Deductions -11,519 -10,928 5.4% -23,371 -22,011 6.2% Net Operational Revenue 98,249 93,289 5.3% 199,458 187,951 6.1% Costs and Expenses -5,824 -4,598 26.7% -10,807 -10,014 7.9% Depreciation -13,966 -13,462 3.7% -28,012 -27,086 3.4% EBITDA 92,715 88,741 4.5% 188,446 177,986 5.9% Gross Profit 78,459 75,230 4.3% 160,640 150,852 6.5% Financial Result -74,264 -49,092 51.3% -132,792 -116,872 13.6% Other Revenues and Expenses 290 49 491.0% -206 49 n.a Income before IR & CSLL 4,485 26,187 -82.9% 27,642 34,029 -18.8% IR & CSLL* -1,521 -8,903 -82.9% -9,394 -11,570 -18.8% Net Income 2,964 17,283 -82.8% 18,248 22,459 -18.7% ISA ENERGIA BRASIL Particip. (50% ) on EBITDA 46,357 44,370 4.5% 94,223 88,993 5.9% ISA ENERGIA BRASIL Particip. (50% ) on Net Income 1,482 8,642 -82.8% 9,124 11,229 -18.7% IE IVAÍ 1H25 Chg (% )1H26Chg (% )2Q26 2Q25 Income Statement (R$ thousand) Gross Operational Revenue 184,463 175,055 5.4% 371,830 350,916 6.0% Operational Revenue Deductions -19,261 -18,623 3.4% -38,555 -37,330 3.3% Net Operational Revenue 165,203 156,432 5.6% 333,274 313,586 6.3% Costs and Expenses -9,656 -8,485 13.8% -17,798 -17,736 0.3% Depreciation -21,345 -20,992 1.7% -42,770 -41,832 2.2% EBITDA 155,837 147,997 5.3% 315,271 295,899 6.5% Gross Profit 134,202 126,956 5.7% 272,707 254,019 7.4% Financial Result -98,102 -45,921 113.6% -180,292 -111,837 61.2% Other Revenues and Expenses 290 49 491.0% -206 49 n.a Income before IR & CSLL 36,390 81,084 -55.1% 92,209 142,231 -35.2% IR & CSLL* -1,025 -13,623 -92.5% -13,095 -22,228 -41.1% Net Income 35,365 67,460 -47.6% 79,114 120,003 -34.1% ISA ENERGIA BRASIL Particip. (50% ) on EBITDA77,918 73,998 5.3% 157,635 147,950 6.5% ISA ENERGIA BRASIL Particip. (50% ) on Net Income17,683 33,730 -47.6% 39,557 60,001 -34.1% 2Q26 2Q25 Chg (% ) AIE (IE IVAÍ + IE PARAGUAÇU + IE AIMORÉS) 1H26 1H25 Chg (% )
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42 ri@brasil.isaenergia.com Annex VII – Covenants (R$ million) The main financial obligations under the financing agreements (financial covenants) to which ISA ENERGIA BRASIL is subject are established as follows: The financing agreements with BNDES (valid until the agreements mature in 2041) must comply with the maximum financial indicators of BNDES Adjusted Net Debt/EBITDA ≤ 3.0 and Net Debt/(Net Debt + Shareholders’ Equity) ≤ 0.6. The balance of these financings with BNDES as of June 30, 2026 amou nted to R$ 665.1 million, and the agreements allow prepayment. The indicators are calculated at the end of each fiscal year. For purposes of calculating and demonstrating compliance with these ratios, the Company must consolidate all subsidiaries and jointly controlled companies (proportionally to its ownership interest), provided that it holds an equity interest equal to or greater than 10%. EBITDA is calculated in accordance with the methodology defined in the agreements, with the latest calculation performed on March 31, 2026. The Net Debt/EBITDA ratio under this methodology was 3.78 in 2Q26. In November 2025, the Company received a letter from BNDES formalizing its prior consent and waiver of the declaration of early maturity of certain financing agreements, in connection with the monitoring of financial indicators for fiscal year 2025. Net Debt 06/30/26 17,774.6 EBITDA LTM 4,707.4 Net Debt/EBITDA 06/30/26 3.78 Shareholders' Equity 06/30/26 22,480.9 Net Debt/(Net Debt + Shareholders' Equity) 06/30/26 0.44 (annual verification) BNDES
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43 ri@brasil.isaenergia.com Annex VIII – Balance Sheet – IFRS Assets (R$ thousand) 30/06/2026 30/06/2025 CURRENT Cash and cash equivalents 468,699 1,356,062 Financial investments 1,288,565 808,924 Concession Asset 4,390,375 4,106,084 Inventories 83,887 72,704 Taxes and contributions to compensate 322,473 229,311 Derivative instruments 0 37,384 Credit with related parties 84,184 126,579 Prepaid expenses 62,557 6,061 Restricted Cash 0 0 Advance to suppliers 0 0 Others 464,434 344,330 7,165,174 7,087,439 NON-CURRENT Long-term Receivables Restricted Cash 20,071 18,888 Concession Asset 34,742,650 32,325,214 Accounts Receivable from the State Finance 2,829,539 2,760,806 Pledges and Escrow 46,317 46,049 Inventories 96,839 94,871 Derivative instruments 35,026 20,406 Others 94,562 76,525 37,865,004 35,342,759 Investments 4,320,138 4,154,815 Imobilized 168,491 180,126 Intangible 435,950 436,233 4,924,579 4,771,174 42,789,583 40,113,933 Total Assets 49,954,757 47,201,372 Consolidated
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44 ri@brasil.isaenergia.com Liabilities and Shareholders' Equity (R$ thousand) 30/06/2026 30/06/2025 CURRENT Loans and financing 92,069 90,082 Debentures 350,737 496,001 Leasing 17,140 18,677 Derivative financial instruments 5,443 2,916 Suppliers 228,937 254,445 Taxes and social charges to be collected 295,495 213,325 Regulatory Charges to be collected 33,001 66,723 Interest on Shareholders' Equity/Dividends 12,484 422,540 Labor obligations 80,601 79,962 Amounts Payable - Vivest 942 1,335 Others 240,580 240,765 1,357,429 1,886,771 NON-CURRENT Long-term Liabilities Loans and financing 642,406 669,117 Debentures 16,592,622 14,696,513 Leasing 30,725 36,959 Derivative financial instruments 1,225 17,312 Suppliers 3,861 3,456 Provision for Contingencies 180,046 163,035 Deferred PIS and COFINS 3,216,050 2,966,130 Deferred Income Tax and Social Contribution 5,403,489 5,287,595 Regulatory Charges to be collected 43,843 35,404 Others 2,124 2,069 Total long-term liabilities 26,116,391 23,877,590 NET EQUITY Shareholders' Equity 3,590,020 3,590,020 Capital Reserves 666 666 Profits Reserve 18,199,688 17,183,674 Other comprehensive results 89,734 97,785 Proposed additional dividends 279,322 279,322 22,159,430 21,151,467 Non-controlling shareholders' share of investment funds 321,507 285,544 22,480,937 21,437,011 Total Liabilities and Shareholders' Equity 49,954,757 47,201,372 Consolidated
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45 ri@brasil.isaenergia.com Annex IX – Income Statement – IFRS Income Statement (R$ thousand) 2Q26 2Q25 Chg (% ) 1H26 1H25 Chg (% ) Gross Operational Revenue 2,904.2 1,626.6 78.5% 5,704 4,314 32.2% Infrastructure Revenue 1,398.3 1,362.8 2.6% 2,898 2,701 7.3% O&M Gross Revenue 350.7 318.8 10.0% 706 651 8.4% Remuneration of concession assets 1,146.7 -64.6 -1874.4% 2,081 943 120.8% Other Revenues 8.5 9.5 -10.9% 19 18 4.4% Deductions from Operational Revenue -306.7 -193.7 58.3% -596 -469 27.1% Net Operational Revenue 2,597.5 1,432.9 81.3% 5,108 3,845 32.9% Operational Costs and Expenses -1,290.7 -1,327.6 -2.8% -2,701 -2,632 2.6% Personnel -133.8 -128.3 4.3% -328 -253 29.8% Materials -387.8 -439.8 -11.8% -1,038 -990 4.8% Services -667.8 -671.4 -0.5% -1,180 -1,225 -3.7% Depreciation -9.4 -8.3 12.5% -18 -17 7.2% Others -91.9 -79.8 15.2% -136 -147 -7.5% Revenues – Periodic Tariff Reset (RTP) 0.0 166.3 -100.0% 0 166 -100.0% Service Income 1,306.8 271.6 381.2% 2,408 1,379 74.5% Financial Income -639.2 -351.9 81.6% -1,122 -703 59.5% Income from Financial Investments 63.2 72.9 -13.3% 120 153 -21.5% Result of Liquid Monetary Variation -281.2 -89.8 213.2% -443 -241 83.7% Interest costs -0.0 -1.3 -98.2% 0 -3 -105.9% Interest/Charges on loans -397.1 -324.4 22.4% -779 -597 30.5% Others -24.1 -9.4 157.6% -21 -16 30.1% Operational Result 667.6 -80.3 -931.3% 1,285 676 90.2% Equity Income 168.4 138.8 21.3% 299 294 1.7% Other Operating Revenues/Expenses 4.8 -2.5 -294.4% 6 0 2006.9% Earnings Before Taxes 840.8 56.1 1399.8% 1,591 970 63.9% Income tax and Social Contribution on Earnings -137.4 176.2 -178.0% -268 -13 1909.4% Current -55.0 11.3 -586.6% -138 -84 65.3% Deferred -82.4 164.9 -149.9% -130 70 -284.9% Consolidated Profit/Loss 703.4 232.3 202.8% 1,323 957 38.2% Non-Controlling Shareholder's Stake -14.8 -17.1 -13.7% -25 -29 -13.1% Consolidated Profit/Loss for the Period 688.6 215.2 220.0% 1,298 928 39.8% Consolidated
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46 ri@brasil.isaenergia.com Annex X – Cash Flow – IFRS (R$ thousand) Cash Flow from Operations (R$ thousand) 1H26 1H25 Cash flow from operational activities -3,116,864 -2,905,291 Net earnings 1,322,519 956,980 Employee benefit - actuarial deficit 2,707 3,846 Depreciation and amortization 18,149 16,927 Deferred PIS and COFINS 249,920 153,145 Deferred IR and CS 129,927 -70,283 Provision for Legal Claims 9,622 20,508 Residual value of permanent assets written off 0 61 Tax benefit - incorporated goodwill 19 18 Income from financial investments -33,335 -57,166 Interest and exchange variations on loans, financing and debentures 1,206,273 877,386 Interest and exchange rate variations on assets and liabilities -23 -39,919 Result of equity income -299,281 -294,181 Accounts Receivable - Concession Assets -5,685,235 -4,457,617 Financial Instruments -21,942 3,655 Realization of Concession asset in the acquisition of Subsidiary 8,657 9,922 Transactions with non-controlling shareholders -24,841 -28,573 Asset Variations 2,623,109 2,507,959 Restricted cash 0 0 Accounts receivable - Concessionaires and Permissionaires 2,983,508 2,567,604 Inventories -13,151 33,138 Accounts Receivable from the State Finance Secretariat -68,733 -89,443 Recoverable taxes and contributions -84,637 73,715 Bonds and linked deposits 694 -73 Prepaid expenses -56,496 -26,514 Credit with subsidiaries 0 0 Others -138,076 -50,468 Liabilities Variations -819 -70,625 Suppliers -25,103 71,909 Taxes and social charges to be collected 168,077 193,086 Tax payments -113,840 -82,747 Labor obligations 639 4,136 Regulatory charges to be collected -25,897 -10,901 Provisions 0 -66,038 Amounts payable Vivest -1,467 0 Global Reversion Reserve -1,240 -1,240 Others -1,988 -178,830 Net Cash from Operating Activities -494,574 -467,957 Investments Activites Cash Flow -249,179 -438,474 Restricted cash -1,183 -1,027 Financial investments -1,763,999 -2,925,957 Redemptions of financial investments 1,353,656 2,484,460 Acquisition of Immobilized -1,347 -7,364 Intangible -11,886 -2,997 Received dividends 175,580 14,411 Cash used in financing activities -143,610 -1,354,742 Addition to loans and debentures 4,789,453 1,446,492 Loan payments (principal) -3,698,909 -988,165 Loan payments (interest) -568,150 -508,518 Leasing Payments (principal and interest) -11,973 -8,500 Derivative instruments 9,759 39,856 Dividends and interest on shareholders' equity paid -663,790 -1,335,907 Net variation in Cash and Cash Equivalents -887,363 -2,261,173 Opening Balance of Cash and Cash Equivalents 1,356,062 2,914,747 Closing Balance of Cash and Cash Equivalents 468,699 653,574 Cash and cash equivalents -887,363 -2,261,173 Consolidated