Earnings release
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2 ri@brasil.isaenergia.com São Paulo, November 3, 2026 – ISA ENERGIA BRASIL S.A. (“ISA ENERGIA BRASIL” or the “Company”; B3: ISAE3 and ISAE4) announces its results for the third quarter of 2026 (3Q26). The Regulatory Results are presented in accordance with the procedures and guidelines issued by the Regulatory Authority and the accounting policies established in the Electricity Sector Accounting Manual (“MCSE”), wit h the aim of facilitating an understanding of the Company’s business. The Regulatory Results are audited annually by th e same independent auditor responsible for the statutory financial statements and are not reviewed quarterly. In addition, results prepared in accordanc e with the rules of the Brazilian Securities and Exchange Commission (“CVM”), the applicable technical p ronouncements issued by the Accounting Pronouncements Committee (“CPC”), and the International Financial Reporting Standards (“IFRS”) issued by the International Ac counting Standards Board (“IASB”) are available in the “Appendices” section of this document.. ¹Adjusted by non-controlling interest. Conference Call 3Q26 Conference call in Portuguese with simultaneous translation into English Date: November 04th, 2026 Time: 10h00 (BRT) / 08h00 (EST) 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) 3Q26 3Q25 Chg (% ) 9M26 9M25 Chg (% ) Net Revenue 1,510.7 1,072.3 40.9% 3,980.3 3,232.8 23.1% PMSO -235.3 -187.5 25.5% -625.2 -551.9 13.3% Manageable PMSO -217.0 -185.5 17.0% -604.3 -546.1 10.6% EBITDA 3,190.1 888.5 259.0% 5,178.2 2,601.3 99.1% EBITDA Margin 211.2% 82.9% 128.3 p.p 130.1% 80.5% 49.6 p.p Net Income¹ 1,904.8 550.0 246.3% 2,436.4 1,143.0 113.2% Net Margin 126.1% 51.3% 74.8 p.p 61.2% 35.4% 25.9 p.p ROE (LTM) 21.7% 20.8% 0.9 p.p 21.7% 20.8% 0.9 p.p Net Debt 17,018.3 12,887.2 32.1% 17,018.3 12,887.2 32.1% CapEx (ex-M&A) 1,103.3 1,205.4 -8.5% 3,379.2 3,415.5 -1.1% Consolidated EBITDA R$ 3,190.1 million (+259.0%) CAPEX R$ 1,103.3 million (-8.5%) Net Revenue R$ 1,510.7 million (+40.9%) Net Debt R$ 17.018,3 million (+32.1%) PMSO R$ 235.3 million (+25.5%) Financial Highlights 3Q26
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3 ri@brasil.isaenergia.com EVENTS OF THE PERIOD 23rd Debenture Issuance On July 16, 2026, the Company completed its 23rd issuance of simple, non -convertible debentures, totaling R$1.5 billion in a single series, with a four -year term and cost of CDI + 0.42% per year. The proceeds raised were fully allocated to replenish the Company’s cash position. Click here for further information. Primary Public Offering of Shares (ISAE4) On July 15, 2026, the Company informed the market about the follow -on public offering ("Follow -on") of a 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 and in agreement with the offering coordinators, by up to 22.2 million preferred shares. The offering was priced on July 23, when 44.4 million preferred shares were iss ued at a price of R$27.00 per share. Settlement took place on July 28. To access the offering documents, click here. 24th Debenture Issuance On July 23, 2026, the Company completed its 24th issuance of simple, non-convertible debentures, raising R$1.0 billion in a single series with a 4.5 -year term and a cost of CDI + 0.42% per year. As provided for in the offering indenture, the settlement period extends through February 2027 and, to date, the proceeds have not been disbursed. Upon settlement, the proceeds will be fully allocated to investments in Retrofitting and Improvements (“R&I”). Click here for further information. Closing of the IE Madeira and IE Garanhuns Asset Unwinding On July 31, 2026, ISA ENERGIA BRASIL completed the unwinding of cross -shareholdings involving its equity interests in IE Madeira and IE Garanhuns, a transaction disclosed to the market through a material fact published on March 19, 2026. Upon completion of the transaction, the Company began to hold 100% of IE Madeira, the concessionaire responsible for 2,385 km of direct current transmission lines, with Annual Allowed Revenue (“AAR”), excluding the Adjustment Portion (“PA”) and net of PIS/COFINS, of R$796.7 million for the 2026/2027 cycle. The Company also ceased to hold an interest in IE Garanhuns, which has 633 km of transmission lines and AAR, excluding PA and net of PIS/COFINS, totaling R$165.3 million for the same cycle. Following the fulfillment of the conditions precedent and the payment of a R$1.2 billion cash adjustment to AXIA, IE Madeira’s results began to be fully consolidated by the Company as of August 2026. For further information, please refer to the material fact. Announcement of Shareholder Distribution On September 29, 2026, ISA ENERGIA BRASIL’s Board of Directors approved the distribution of earnings related to the results for the first half of 2026, in the form of Interest on Equity (“IoE”), in the total amount of R$398.7 million, corresponding to R$0.566877 per share of both classes. The distribution of the IoE amount, net of withholding income tax, was divided into three installments, each with its respective record date and ex -rights date. Click here to access the full notice to shareholders. Record Ex-right Payment 8-Oct-26 9-Oct-26 7-Dec-26 132.9 0.188959 9-Nov-26 10-Nov-26 7-Dec-26 132.9 0.188959 25-Nov-26 26-Nov-26 7-Dec-26 132.9 0.188959 398.7 0.566877 Interest on Equity ("IOE") 29-Sep-26 Result of the fiscal year 2026 R$ / shareEarning Type Deliberation Date Date Total¹ (R$ million) Distribution Base
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4 ri@brasil.isaenergia.com Notes on financial information The financial information presented in this document refers to the three-month period ended September 30, 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) 3Q26 3Q25 Chg (% ) 9M26 9M25 Chg (% ) (=) Regulatory Net Income 1,904.8 550.0 246.3% 2,436.4 1,143.0 113.2% (+) Non-controlling shareholder particp. 7.8 18.0 -56.4% 32.7 46.5 -29.8% (+) IRPJ/CSLL 712.5 -39.9 n.a 793.8 91.1 771.4% (-) Equity Income -34.2 -100.4 -66.0% -197.2 -267.0 -26.1% (+) Financial Result 348.1 293.1 18.7% 1,469.9 996.3 47.5% (+) Depreciation/Amortization 251.0 167.6 49.8% 642.6 591.4 8.7% (=) Regulatory EBITDA 3,190.1 888.5 259.0% 5,178.2 2,601.3 99.1% (+) Equity Income 34.2 100.4 -66.0% 197.2 267.0 -26.1% (=) Regulatory EBITDA CVM 156/2022 3,224.2 988.9 226.1% 5,375.4 2,868.3 87.4% Consolidated
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5 ri@brasil.isaenergia.com CONTENT EVENTS OF THE PERIOD 3 OPERATING REVENUE 7 EBITDA AND MARGIN 12 FINANCIAL RESULT 13 EQUITY INCOME 14 NET INCOME¹ 16 COMPARISON OF RESULTS (REGULATORY VS. IFRS) 17 INDEBTEDNESS 19 INVESTMENTS 21 INVESTMENTS IN RETROFITTING AND IMPROVEMENTS PROJECTS (“R&I”) 21 INVESTMENTS IN GREENFIELD PROJECTS 22 CAPITAL MARKETS 23 EARNINGS 24 SUSTAINABILITY 25 HIGHLIGHTS OF THE PERIOD 25 SUSTAINABILITY KPI’S 26 OTHER RELEVANT INFORMATION 29 PERIODIC TARIFF REVIEW (PRT) – NEW CONCESSIONS 29 PAULISTA CONCESSION RENEWAL - CONTRACT 059/2001 (RBNI/RBSE) 32 SUPPLEMENTARY RETIREMENT PLAN – LAW 4,819/58 34 GLOSSARY 35 ATTACHMENTS 38
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6 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 IENS¹ measurement for the third quarter of 2026: 1 Connection assets associated with distribution companies with voltage levels below 230 kV are considered. 2 September data for the SIN were not made available by the National Electric System Operator (“ONS”). Variable Portion The Variable Portion ("PV") is a regulatory mechanism applied by the Brazilian Electricity Regulatory Agency ("ANEEL") that reduces the Annual Allowed Revenue ("AAR") of transmission concessionaires when failures, outages or operating restrictions are recorded. The deduction is proportional to the unavailability verified. The indicator considers Basic Grid assets with voltage levels equal to or above 230 kV and is ca lculated as the ratio between the gross PV for the period and the corresponding AAR. * 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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7 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 059/2 001. Consolidated gross revenue reached R$1,721.7 million in 3Q26, an increase of R$471.1 million (+37.7%) compared to 3Q25. In 9M26, consolidated gross revenue increased by R$817.9 million (+22.0%) compared to 9M25. In addition to the tariff adjustment for the 2026/2027 cycle, including the 4.72% inflation adjustment to the AAR based on Brazil’s Broad National Consumer Price Index (“IPCA”), the main revenue variations in the period were: Paulista Concession (contract 059/2001) ▲ Incorporation of the AAR from large-scale Retrofitting and Improvement (“R&I”) projects energized over the last 12 months; Auctioned Contracts ▲ Beginning of the receipt of R$478.9 million in AAR (2026/2027 cycle) from the Riacho Grande, Jacarandá and Piraquê projects, which started operations between October 2025 and June 2026; ▲ Consolidation of 100% of IE Madeira’s results in consolidated revenue as of August 2026 (+R$144.5 million), following the completion of the unwinding of cross-shareholdings with AXIA Energia. Previously, the Company’s 51% interest was recognized as equity income. Operating Revenue (R$ million) 3Q26 3Q25 Chg (% ) 9M26 9M25 Chg (% ) Eletric Network Revenue 1,710.6 1,239.4 38.0% 4,503.7 3,684.8 22.2% RBSE 519.5 511.5 1.6% 1,542.6 1,648.7 -6.4% Paulista Concession (059/2001 contract) 519.3 468.1 10.9% 1,484.7 1,340.2 10.8% Operating & Maintenance (O&M)¹ 249.2 238.3 4.6% 725.7 708.5 2.4% Retrofitting & Improvements (R&I) 270.1 229.8 17.5% 759.0 631.7 20.2% New Concessions 551.9 265.1 108.2% 1,274.5 773.7 64.7% Basic Project (CAEE + O&M) 533.4 247.4 115.6% 1,220.5 739.2 65.1% Retrofitting & Improvements (R&I) 18.6 17.7 4.9% 54.0 34.4 56.8% Adjustment Portion (PA) and anticipation 98.5 -52.2 n.a 142.2 -163.6 n.a Variable Portion (PV) -16.0 -15.6 2.5% -49.6 -44.2 12.3% Regulatory charges ex RAP (CDE and PROINFA) 37.2 62.5 -40.4% 109.4 130.0 -15.8% Others 11.1 11.2 -0.5% 32.9 33.9 -2.9% Gross Revenue 1,721.7 1,250.6 37.7% 4,536.6 3,718.7 22.0% Deduction -211.0 -178.2 18.4% -556.1 -485.9 14.4% Taxes and Contributions (PIS & Cofins) -149.3 -105.6 41.3% -391.8 -319.5 22.6% Regulatory charges ex AAR (CDE and PROINFRA) -33.7 -57.8 -41.7% -98.7 -116.9 -15.6% Regulatory charges in AAR (P&D, RGR and TFSEE) -28.1 -14.8 89.3% -65.6 -49.5 32.5% Net Revenue 1,510.7 1,072.3 40.9% 3,980.6 3,232.8 23.1% Consolidated
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8 ri@brasil.isaenergia.com Adjustment Portion (“PA”) and Anticipation ▲ Positive PA of R$150.1 million related to the tariff-cycle adjustment (2025/2026 vs. 2026/2027); ▲ Reimbursement from the Energy Development Account (“CDE”): CDE is classified as a pass-through item and does not constitute Company revenue. Accordingly, the Company changed its accounting treatment so that CDE would no longer be recognized in the income s tatement as of August 2025, since the gross CDE revenue recorded was fully provisioned in the following month; ▼ Lower volume of advances related to the sector’s revenue surplus or deficit (-R$37.2 million). NET REVENUE Net revenue increased by R$438.3 million (+40.9%) compared to 3Q25, totaling R$1,510.7 million. In 9M26, net revenue increased by R$747.8 million (+23.1%) compared to 9M25. ¹ Considers adjustment by the IPCA and project energization | ² Charges and taxes on revenue . Net revenue excluding RBSE reached R$1,039.2 million in 3Q26, an increase of R$431.1 million (+70.9%) compared to 3Q25. In 9M26, cumulative net revenue excluding RBSE increased by R$844.1 million (+48.6%) compared to 9M25. PA + Anticipations + Reimbursements (R$ Million) 3Q26 3Q25 Chg (% ) PA Cycle Readjustment 150.1 0.0 n.a. Improvements annual payment 11.5 11.0 4.7% Anticipation (Sector Surplus | Deficit)) -63.1 -36.8 71.4% CDE Reimbursement 0.0 -26.4 -100.0% TOTAL 98.5 -52.2 n.a. Consolidated Net Revenue – 9M26 vs. 9M25 (R$ million) Net Revenue (R$ million) Net Revenue – 3Q26 vs. 3Q25 (R$ million)
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9 ri@brasil.isaenergia.com O&M Costs and Expenses The main events that caused variations in manageable PMSO during the period were as follows: ▲ Personnel: (i) higher costs related to salaries, payroll charges and benefits due to the 2025/2026 collective bargaining agreement; and (ii) the full consolidation of IE Madeira as of August 2026. These increases were partially offset by lower expenses associated with severance payments. ▲ Services: higher expenses associated with: (i) legal success fees; (ii) cleaning and mowing services; and (iii) travel for training and support for new operations. The increase in expenses was partially offset by lower expenditure on corporate training. ▲ Other: higher costs associated with: (i) property tax (“IPTU”), mainly due to the update of the market value of properties and inflation adjustments; and (ii) insurance renewals. These effects were partially offset by lower expenses related to taxes levied on foreign services. In addition to the manageable PMSO variations explained above, the Company recorded R$15.5 million in non-recurring expenses related to the unwinding of cross -shareholdings completed in 3Q26. During the quarter, the private pension provision (an actuarial liability estimated based on benefits, as provided for under CPC 33 ) decreased by R$0.6 million (-29.6% vs. 3Q25). This variation had no cash effect and was mainly explained by the higher discount rate used to calculate the present value of future obligations, resulting from the increase in NTN -B yields considered in the an nual actuarial reassessment conducted in December 2025. 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 a R$23.6 million gain from contingencies in 3Q26, compared to an expense of R$0.2 million in 3Q25. The variation was mainly due to the conclusion of legal proceedings related to the RBNI indemnification upon O&M Costs and Expenses (R$ million) 3Q26 3Q25 Chg (% ) 9M26 9M25 Chg (% ) Personnel -115.7 -100.5 15.2% -331.1 -310.5 6.6% Material -6.3 -5.6 11.2% -17.2 -16.9 2.2% Services -66.6 -54.1 23.2% -174.5 -146.0 19.5% Others -28.4 -25.4 12.1% -81.4 -72.7 12.0% Manageable PMSO -217.0 -185.5 17.0% -604.3 -546.1 10.6% Non-recurring -16.9 0.0 N.A. -16.9 0.0 N.A. Private Pension Entity -1.4 -1.9 -29.6% -4.1 -5.8 -29.6% PMSO -235.3 -187.5 25.5% -625.2 -551.9 13.3% Contingencies 23.6 -0.2 n.a 19.2 -20.8 n.a Depreciation -251.0 -167.6 49.8% -642.6 -591.3 8.7% Other costs and expenses -227.4 -167.8 35.5% -623.3 -612.2 1.8% Total -462.7 -355.2 30.2% -1,248.6 -1,164.0 7.3% Consolidated Efficiency Indicator (R$ million)
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10 ri@brasil.isaenergia.com the renewal of the Paulista Concession Agreement. The settlement entered into with AXIA Energia resulted in a payment of R$32.1 million, compared to a provision of R$63.4 million, allowing the Company to reverse R$31.3 million during the quarter. DEPRECIATION The Company recorded depreciation expense of R$250.9 million in 3Q26, an increase of 49.8% (R$83.4 million) compared to 3Q25, mainly due to: ▲ Recognition of a depreciation provision related to the Piraquê project, which began commercial operations in 2Q26 (R$29.8 million); ▲ Full consolidation of IE Madeira as of August 2026, with an impact of R$24.3 million on depreciation expenses recorded in 3Q26; ▲ Progress in the unitization of R&I projects under the Paulista Concession over the last 12 months (+R$18.9 million); ▲ Unitization of Riacho Grande’s assets with ANEEL (+R$5.3 million compared to 3Q25). As a result, operating costs and expenses totaled R$462.7 million in 3Q26 (+30.2% compared to 3Q25). In 9M26, they totaled R$1,248.6 million (+7.3% compared to 9M25).
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11 ri@brasil.isaenergia.com Other Operating Income and Expenses * Costs associated with the decommissioning, disposal and write-off of assets. Other Operating Income and Expenses totaled R$1,891.2 million in income in 3Q26, compared to R$3.8 million in 3Q25, mainly reflecting income of R$1,938.3 million related to the one -off accounting effect of the unwinding of the equity interests in IE Madeira and IE Garanhuns, as shown in the table below. Other variations included: (i) a R$31.6 million reduction in gains and compensation related to the Centro Substation, approved by ANEEL in 3Q25; (ii) a R$9.0 million reduction in the monetary adjustment of c ourt-ordered payments; (iii) a negative impact of R$2.2 million from the disposal of obsolete assets, resulting from the timing mismatch between the accounting write -offs of the assets and the recognition of their respective disposals; and (iv) a R$3.7 mil lion increase in asset decommissioning costs related to dismantling activities carried out as part of Retrofitting and Improvements projects. The unwinding of the equity interests in IE Madeira and IE Garanhuns resulted in a positive, non -recurring, non-cash accounting effect of R$1,938.3 million (“One -Off Accounting Effect (Assets’ Unwinding)”). This effect comprises: ( i) a bargain purchase gain related to the additional 49% interest acquired in IE Madeira (R$655.2 million); (ii) the fair value remeasurement of the previously held 51% interest in IE Madeira (R$1,211.0 million); and (iii) a gain of R$72.1 million on the disposal of the 51% interest in IE Garanhuns, as shown in the table below: Other Operating Income and Expenses (R$ million) 3Q26 3Q25 Chg (% ) 9M26 9M25 Chg (% ) Income 1,941.2 58.3 3231.8% 1,957.6 68.1 2775.3% Disposal of Non‑Operational Assets -2.2 7.9 n.a 2.9 12.9 -77.2% Update of amounts of warrants receivable (SJC terrain) 3.1 12.1 -74.4% 9.0 16.9 -47.0% Insurance Indemnity Proceeds 0.0 4.8 -100.0% 1.9 4.8 -60% Gain and Remuneration From SE Centro 1.9 33.5 -94.3% 5.5 33.5 -84% One-off accounting effect (Asset unwinding) 1,938.3 0.0 N.A. 1,938.3 0.0 N.A. Expenses -49.4 -55.7 -11.4% -152.1 -129.6 17.3% Disposal of Non‑Operational Assets -0.8 -8.7 -90.8% -8.3 -14.3 -41.8% Amortization of capital gains (PBTE and SF Energia) -12.8 -15.0 -14.3% -39.2 -43.2 -9.3% Cost of decommissioning assets* -35.7 -32.0 11.7% -104.5 -72.1 45.0% Others -0.7 0.0 N.A. -1.7 1.4 N.A. Eliminations 0.0 1.3 -100.0% 0.0 1.3 -100.0% Total 1,891.2 3.8 n.a 1,803.9 -58.9 n.a Consolidated (R$ million) Regulatory Bargain purchase gain 655.2 Remeasurement of previously held interest (CPC 15 - item 42) 1,211.0 Gain on disposal of Garanhuns 72.1 One-off Accounting Effect (Asset Unwinding) 1,938.3 One-off Accounting Effect (Asset Unwinding)
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12 ri@brasil.isaenergia.com EBITDA and MARG IN In addition to the recognition of the One-Off Accounting Effect (Assets’ Unwinding), the variation was mainly explained by: ▲ Full consolidation of IE Madeira’s operations as of August 2026; ▲ Start of operations of greenfield projects and large -scale Retrofitting and Improvements projects over the last 12 months; ▲ Tariff adjustment for the 2026/2027 cycle; ▲ Improvement in the efficiency indicator, with a reduction in the PMSO -to-net-revenue ratio in 9M26 compared to 9M25, reflecting revenue growth above the increase in operating expenses. EBITDA from ISA ENERGIA BRASIL’s interest in jointly controlled companies totaled R$86.8 million in 3Q26, a decrease of R$104.6 million ( -54.6%) compared to 3Q25. In 9M26, EBITDA from ISA ENERGIA BRASIL’s interest in jointly controlled companies totaled R$448.5 million, down 14.8% compared to 9M25. In August, following the completion of the unwinding of equity interests, IE Madeira began to be fully consolidated into the Company’s results, while IE Garanhuns ceased to be part of the Company’s assets. Therefore, equity income from IE Madeira and IE Garanhuns in 3Q26 refers exclusively to July 2026. Total EBITDA, considering ISA ENERGIA BRASIL’s consolidated results and its interest in jointly controlled companies, was R$3,276.9 million in 3Q26 (+203.5% vs. 3Q25). Further details are available in the “Equity Income” section of this document (click here). ¹ Equity income from IE Madeira and IE Garanhuns includes results recognized through July 2026, due to the completion of the unwinding of the equity interests on July 31, 2026. EBITDA (R$ million) 3Q26 3Q25 Chg (% ) 9M26 9M25 Chg (% ) Net revenue 1,510.7 1,072.3 40.9% 3,980.3 3,232.8 23.1% Costs and expenses (ex-depreciation) -211.7 -187.7 12.8% -606.0 -572.7 5.8% Other expenses and revenues (ex-amortization) 1,891.2 3.8 N.A. 1,803.9 -58.8 N.A. EBITDA 3,190.1 888.5 259.0% 5,178.2 2,601.3 99.1% (-) One-Off Accounting Effect (Assets' Unwinding) -1,938.3 0.0 N.A. -1,938.3 0.0 N.A. EBITDA Pro forma 1,251.7 888.5 40.9% 3,239.8 2,601.3 24.5% Consolidated EBITDA (R$ million) 3Q26 3Q25 Chg (% ) 9M26 9M25 Chg (% ) Consolidated 3,190.1 888.5 259.0% 5,178.2 2,601.3 99.1% Non-consolidated 86.8 191.2 -54.6% 448.5 526.7 -14.8% IE Madeira (51%)¹ 22.8 101.7 -77.6% 191.6 256.8 -25.4% IE Garanhuns (51%)¹ 4.9 14.0 -65.0% 40.1 46.5 -13.7% IE Aimorés (50%) 12.5 12.9 -3.2% 38.0 36.7 3.6% IE Paraguaçu (50%) 19.9 19.5 2.2% 57.8 54.6 5.8% IE Ivaí (50%) 26.8 43.1 -38.0% 121.0 132.1 -8.4% Total 3,276.9 1,079.7 203.5% 5,626.7 3,128.0 79.9% Consolidated + Non-consolidated
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13 ri@brasil.isaenergia.com Financial Result The Company recorded net financial expenses of R$348.1 million in 3Q26, an increase of R$55.0 million (+18.7%) compared to 3Q25: ▲ Interest and charges on loans: reflected the higher average debt balance, driven by (i) the 20th, 22nd and 23rd debenture issuances, totaling R$4.5 billion, to finance the Company’s growth; and (ii) the consolidation of IE Madeira’s financial expenses. These effects were partially offset by the lower CDI rate during the period (3.38% in 3Q26 vs. 3.65% in 3Q25) and an approximately 80-basis-point reduction in the average spread on the institutional debenture issuances included in the liability -management transaction carried out through th e 21st debenture issuance in 1Q26; ▼ Monetary variation: the decrease mainly reflected (i) the lower IPCA variation ( -0.09% in 3Q26 vs. 0.39% in 3Q25), partially offset by (ii) a R$3.0 billion increase in gross debt indexed to IPCA compared to 3Q25. For accounting purposes, 3Q results reflect inflation from June through August. ▲ Other financial expenses: the increase in derivative-related financial expenses in 3Q26 compared to 3Q25 mainly reflected the mark-to-market adjustment of a swap in which the Company holds a long IPCA position and a short CDI position. The upward shift in the forward CDI curve increased the present value of the short position, negatively affecting the derivative’s fair value and resulting in higher financial expenses in the quarter ( -R$20.5 million); Net financial expenses increased by 47.5% in 9M26, or R$473.6 million, compared to R$996.3 million in 9M25. Financial Result (R$ million) 3Q26 3Q25 Chg (% ) 9M26 9M25 Chg (% ) Financial Income 107.9 115.4 -6.5% 282.4 332.3 -15.0% Financial investment income 92.5 90.0 2.7% 212.8 243.4 -12.6% Other financial income 15.4 25.4 -39.3% 69.6 88.9 -21.7% Financial Expenses -456.0 -408.6 11.6% -1,752.3 -1,328.5 31.9% Interest and charges on loans -428.5 -336.7 27.2% -1,207.4 -936.4 28.9% Monetary variation 8.5 -54.6 -115.6% -436.8 -337.7 29.4% Other financial expenses -36.1 -17.3 108.8% -108.1 -54.4 98.6% Total -348.1 -293.1 18.7% -1,469.9 -996.3 47.5% Consolidated
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14 ri@brasil.isaenergia.com Equi ty Income Equity income totaled R$34.2 million in 3Q26, a reduction of R$66.2 million (-66.0%) compared to 3Q25, mainly due to the effects of the unwinding of the equity interests with AXIA Energia. In 9M26, equity income totaled R$197.2 million, down 26.1% compared to 9M25. The other variations are detailed below: Aliança Interligação Elétrica (“AIE”) Comprising three projects in partnership with TAESA (Aimorés, Paraguaçu and Ivaí) AIE recorded a decrease of R$8.5 million in 3Q26 (-29.0% vs. 3Q25), mainly explained by: • IE Aimorés and IE Paraguaçu: higher financial expenses on debentures, as the debt proceeds were disbursed at the end of 2Q25, partially offset by the IPCA adjustment for the tariff cycle. • IE Ivaí: lower operating results, mainly due to the recognition of a provision related to the Variable Portion for Delayed Commercial Operation (“PVA”) associated with the project’s startup in 2022, following ANEEL’s denial of the administrative appeal. This effec t was partially offset by: (i) lower monetary adjustment on debt due to the lower IPCA² in 3Q26; and (ii) the IPCA adjustment for the 2026/2027 tariff cycle. Click here to view the condensed income statement of the jointly controlled companies. ¹ Equity income from IE Madeira and IE Garanhuns includes results recognized through July 2026, due to the completion of the un winding of the equity interests on July 31, 2026. | ² IPCA: -0.09% in 3Q26 vs. +0.39% in 3Q25 Equity Income (R$ million) 3Q26 3Q25 Chg (% ) 9M26 9M25 Chg (% ) IE Madeira (51% )¹ 10.0 61.8 -83.9% 107.2 144.5 -25.8% IE Garanhuns (51% )¹ 3.4 9.3 -63.3% 29.6 33.2 -10.8% AIE (50% ) 20.8 29.2 -29.0% 60.3 89.2 -32.4% IE Aimorés 5.8 7.1 -18.5% 18.6 26.5 -29.9% IE Paraguaçu 8.3 9.0 -8.2% 25.9 38.4 -32.5% IE Ivaí 6.7 13.1 -48.9% 15.8 24.3 -35.0% Total 34.2 100.4 -66.0% 197.2 267.0 -26.1% Consolidated
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15 ri@brasil.isaenergia.com IRPJ and CSLL The Company recorded an Income Tax and Social Contribution on Net Income (“IR/CSLL”) expense of R$712.5 million in 3Q26, compared to income of R$39.9 million in 3Q25. In 3Q25, the distribution of R$444.7 million in Interest on Equity (“IoE”) reduced the IR/CSLL tax base. In 3Q26, although the distribution of R$398.7 million in IoE also generated a tax benefit, this effect was more than offset by the R$659.0 million negative deferred tax impact arising from the One-Off Accounting Effect related to the unwinding of the equity interests, as shown in the table below: In 9M26, current and deferred IR/CSLL expenses totaled R$793.8 million, compared to R$91.1 million in 9M25 . IRPJ|CSLL (R$ million) 3Q26 3Q25 Chg (% ) 9M26 9M25 Chg (% ) Current 27.4 38.6 -29.1% -108.1 -45.0 140.1% Deferred -739.9 1.2 n.a -685.7 -46.1 1388.3% Total -712.5 39.9 n.a -793.8 -91.1 771.4% Effective rate 27.1% -7.5% 35 p.p 24.3% 7.1% 17.2 p.p Consolidated (R$ million) Regulatory One-off accounting effect (Asset unwinding) 1,938.3 IR/CSLL current – IE Garanhuns -24.5 IR/CSLL deferred – IE Madeira (CPC 32) -634.5 IR/CSLL without/One-off accounting effect -659.0 Total 1,279.3 IRPJ/CSLL
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16 ri@brasil.isaenergia.com Net Income ¹ As a result of the factors explained above, net income for the quarter totaled R$1,904.8 million, an increase of R$1,354.8 million (+246.3%) compared to 3Q25. In 9M26, net income totaled R$2,436.4 million. Excluding the One-Off Accounting Effect (Assets Unwinding) net of IR/CSLL, net income totaled R$625.5 million in 3Q26, an increase of R$75.5 million compared to 3Q25. In 9M26, net income excluding this effect totaled R$1,157.1 million, up 1.2% compared to 9M25. As this is a non -cash accounting effect, the One -Off Accounting Effect (Assets Unwinding) will be excluded from regulatory net income, which is used as a reference for the Company’s earnings distribution practices . ¹ adjusted by non-controlling interest | ² Personnel, Material, Services and Others. Net Income¹ 3Q26 vs. 3Q25 (R$ million) Net Margin 51.3% Net Income¹ 9M26 vs. 9M25 (R$ million) Net Margin 29.1% Net Margin 41.4% Net Margin 35.4%
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17 ri@brasil.isaenergia.com Comparison of Results (Regulat ory vs. IFRS) In 3Q26, the Company recorded net income of R$913.8 million under IFRS accounting, an increase of R$129.2 million (+16.4%) compared to 3Q25. The detailed IFRS income statement 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 remuner ation 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 to 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. Business combinations and disposal of investments: In the asset unwinding transaction, the accounting effects differ between IFRS and regulatory accounting due to the carrying amounts of the investments under each accounting framework. For the acquisition of a 49% interest in IE Madeira, the accounting treatment considers the fair value of the company’s equity, based on an appraisal report. Under regulatory accounting, the investment’s carrying amount was lower than its fair value, resulting in the recognition of a gain, whereas under IFRS, the carrying amo unt exceeded its fair value, resulting in the recognition of a loss. On the disposal of Garanhuns, the consideration received of R$462 million was lower than the investment’s carrying amount under IFRS, resulting in a loss of R$187 million. Under regulatory accounting, in turn, the investment’s carrying amount was lower than the consideration received, resulting in a gain of R$72 million. Income Statement (IFRS) (R$ million) 3Q26 3Q25 Chg (% ) 9M26 9M25 Chg (% ) Net Operating Revenue 2,333.7 2,559.0 -8.8% 7,442.0 6,403.9 16.2% Costs of Infrastructure Implementation Services, operation and maintenance and services provided -1,272.6 -1,340.5 -5.1% -3,839.1 -3,831.3 0.2% Gross Profit 1,061.1 1,218.4 -12.9% 3,602.8 2,572.6 40.0% Operational Revenue and Expenses 325.3 61.2 431.3% 496.4 380.8 30.4% Earnings before financial income and expenses and taxes on earnings 1,386.4 1,279.7 8.3% 4,099.3 2,953.5 38.8% Financial Income -348.4 -293.3 18.8% -1,470.7 -996.8 47.5% Earnings Before Taxes 1,038.0 986.4 5.2% 2,628.6 1,956.7 34.3% Income tax and Social Contribution on Earnings -116.3 -183.6 -36.7% -384.4 -196.9 95.2% Consolidated Profit/Loss 921.7 802.8 14.8% 2,244.2 1,759.8 27.5% Non-Controlling Shareholder's Stake -7.8 -18.0 -56.4% -32.7 -46.5 -29.8% Consolidated Profit/Loss for the Period 913.8 784.8 16.4% 2,211.5 1,713.2 29.1% Consolidated
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18 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) 3Q26 3Q25 Var (% ) 9M26 9M25 Var (% ) (=) Net Profit IFRS 913.8 784.8 16.4% 2,211.5 1,713.2 29.1% (+) Non-controlling shareholder particp. 7.8 18.0 -56.4% 32.7 46.5 -29.8% (+) IRPJ/CSLL 116.3 183.6 -36.7% 384.4 196.9 95.2% (-) Equity Income -59.9 -109.5 -45.3% -359.1 -403.7 -11.0% (+) Financial Result 348.4 293.3 18.8% 1,470.7 996.8 47.5% (+) Depreciation/Amortization 14.9 8.7 71.5% 33.1 25.6 29.0% (=) EBITDA IFRS 1,341.5 1,178.9 13.8% 3,773.2 2,575.4 46.5% (+) Equity Income 59.9 109.5 -45.3% 359.1 403.7 -11.0% (=) EBITDA IFRS CVM 156/2022 1,401.3 1,288.4 8.8% 4,132.4 2,979.1 38.7% Consolidated (R$ million) 3Q26 3Q25 Chg (% ) 9M26 9M25 Chg (% ) EBITDA IFRS (CVM 156/22) 1,401.3 1,288.4 8.8% 4,132.4 2,979.1 38.7% (-) Infrastructure implementation revenue -1,408.0 -1,516.8 -7.2% -4,257.5 -4,228.9 0.7% (-) Concession assets remuneration -726.6 -1,060.8 -31.5% -2,807.6 -2,003.4 40.1% (-) Efficiency gains in infrastructure implementation -20.8 0.1 n.a -69.4 10.7 n.a (-) O&M Revenue -464.0 -294.2 57.7% -1,170.1 -945.7 23.7% (+) Electric network use revenue 1,710.6 1,239.4 38.0% 4,503.7 3,684.8 22.2% (+) Other Revenue 0.4 1.1 -59.7% 2.9 5.6 -47.6% (+) Deferred PIS and COFINS 85.4 144.7 -41.0% 336.3 305.9 10.0% (+) Infrastructure implementation cost 1,103.9 1,194.7 -7.6% 3,376.5 3,404.8 -0.8% (-) O&M Cost 10.6 6.2 70.5% 16.9 18.3 -7.7% (-) General and Administrative expenses -1.2 -0.9 31.9% 8.1 6.8 18.5% (-) Equity Income -25.7 -9.2 180.8% -161.9 -136.7 18.4% (-) Other operational revenues (expenses) 1,607.4 -10.5 n.a 1,514.1 -73.5 n.a REGULATORY EBITDA (CVM 156/22) 3,224.2 988.9 226.1% 5,375.4 2,868.3 87.4% Equity Income -34.2 -100.4 -66.0% -197.2 -267.0 -26.1% REGULATORY EBITDA 3,190.1 888.5 259.0% 5,178.2 2,601.3 99.1% Consolidated
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19 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 Aimorés, IE Paraguaçu and IE Ivaí) and refer to shares 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$19,805.4 million at the end of 3Q26, an increase of R$3,798.0 million (+23.7%) compared to the balance at the end of 4Q25. The Company also ended 3Q26 with total cash and cash equivalents of R$2,968.1 million (+37.1% vs. December 31, 2025). The Company completed the following debt issuances in 9M26: • 21st debenture issuance (R$3.9 billion): proceeds fully used for the optional acquisition of the 9th, 13th, 15th (first, second and third series) and 16th debenture issuances as part of a liability-management transaction; • 22nd debenture issuance (R$1.0 billion): incentivized green issuance comprising two series, maturing in 2041 and bearing interest at IPCA plus 6.46% per year; • 23rd debenture issuance (R$1.5 billion): conventional single -series issuance, maturing in 2030 and bearing interest at CDI plus 0.42% per year; • 24th debenture issuance (R$1.0 billion): single-tranche issuance maturing in 2030, at a cost of CDI + 0.42% p.a. It is worth noting that, as provided for in the offering indenture, the settlement period extends through February 2027. As of the date hereof, the proceeds have not yet been disbursed and, therefore, are not included in the Company’s indebtedness. The liability -management transaction carried out through the 21 st debenture issuance in 1Q26, combined with the reductions in the annualized CDI rate (-125 bps vs. 2025) and the IPCA accumulated over the last 12 months ( -24 bps vs. 2025), contributed to reducing the Company’s average nominal cost of debt, which stood at 11.80% p.a. as of September 30, 2026 (vs. 12.36% p.a. as of December 31, 2025). Considering the IPCA accumulated over the last 12 months, the average real cost* of debt stood at 7.27% as of September 30, 2026, a reduction of 29 bps compared to 7.56% as of December 31, 2025. The average term of consolidated debt was 8.0 years as of September 30, 2026 (vs. 8.2 years as of December 31, 2025), a profile consistent with the nature of the business, which combines low risk with high revenue predictability and operating cash flow generation. These characteristics were highlighted by Fitch when it reaffirmed the Company’s local- scale corporate rating of “AAA,” with a stable outlook, in July 2026. Excluding cash and cash equivalents held by jointly controlled companies, the Company’s net debt reached R$17,018.3 million as of September 30, 2026, an increase of R$2,890.4 million (+20.5% vs. December 31, 2025). The increase in gross debt was mainly due to: (i) R$2.5 billion raised through the 22nd and 23rd debenture issuances; (ii) the consolidation of IE Madeira debt (R$0.6 billion); and (iii) monetary adjustment on debt. The increase in net debt was partially offset by the R$1.2 billion raised through the primary public offering of shares (follow -on), of which R$600 million was allocated to the cash adjustment paid to AXIA upon completion of the transaction to unwind the e quity interests. The remaining R$600 million will be allocated to investments in Retrofitting and Improvements . It is worth noting that only the financing agreements with BNDES (R$649.9 million as of September 30, 2026 ) have financial covenants. These covenants are measured annually based on the Net Debt/EBITDA ratio recorded as of December 31 and are subject to a limit of 3.0x. The managerial leverage ratio, calculated in accordance with the BNDES methodology, was 3.50x as of September 30, 2026, compared to 3.63x as of December 31, 2025. Further details on leverage are available in Annex VII of this document, while additional information on the Company’s indebtedness is available on its website (click here). DEBT R$ (million) Gross Debt³ 19,805.4 16,007.3 23.7% Short-term Debt 647.7 604.8 7.1% Long-term Debt 19,157.7 15,402.6 24.4% Consolidated Availabilities 2,968.1 2,165.0 37.1% ISA ENERGIA BRASIL and Subsidiaries 2,787.1 1,879.4 48.3% Jointly-controlled subsidiaries¹ 181.0 285.5 -36.6% Consolidated Net Debt² 17,018.3 14,127.9 20.5% 09/30/26 12/31/25 Chg (% )
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20 ri@brasil.isaenergia.com (*) Ratio between (i) the average nominal cost; and (ii) the IPCA accumulated over the last 12 months. ¹ CDI: 3.65% in 3Q25 and 3.38% in 3Q26. Gross debt amortization schedule (R$ million) Debt Indexation 09/30/2026
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21 ri@brasil.isaenergia.com INVESTMENTS Investments by ISA ENERGIA BRASIL, its subsidiaries and jointly controlled companies totaled R$1,103.3 million in 3Q26, a decrease of R$102.1 million (-8.5%) compared to 3Q25, mainly reflecting the lower number of greenfield projects under construction fol lowing the energization of the Riacho Grande, Jacarandá and Piraquê projects, completed between October 2025 and June 2026. On the other hand, the Company increased investments in Retrofitting and Improvements (“R&I”), which totaled R$578.5 million in 3Q26, up 32.1% compared to the same period of 2025. Investments in Retrofitting and Improvements Projects (“R&I”) Of the R$578.5 million invested by the Company in 3Q26, approximately 57% was allocated to Retrofitting projects and 43% to Improvement projects. Investments in R&I totaled R$1,393.9 million in 9M26, up 24.1% compared to the same period of 2025, reflecting the Company’s continued investments in asset modernization and transmission -system reliability. Of this amount, approximately 60% was allocated t o large-scale projects and 40% to small -scale projects. In addition to improving service quality, asset renewal supports operating -efficiency gains and the optimization of Operations and Maintenance (“O&M”) costs. Regarding project energization, approximately R$947 million in investments started operations in the first nine months of 2026, of which 16% related to large-scale projects and 84% to small-scale projects. For small-scale projects, revenue is enabled in the Periodic Tariff Review ("PTR") following energization, with retroactive effects to the respective commercial operation date. For large-scale projects, revenue is previously established through an Authorizing Resolution ("ReA") and begins to be received upon the start of commercial operations. Regarding investment planning, at the end of 3Q26, the Company's authorized project portfolio totaled R$7.6 billion, 5.1% higher than at the end of 2Q26, due to: (i) new authorizations granted by ANEEL; (ii) updates to project costs; and (iii) monetary adjustment by IPCA. These effects were partially offset by investments made during the quarter.
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22 ri@brasil.isaenergia.com Investments in Greenfield Projects The Company invested R$524.9 million in auctioned projects in 3Q26, down 31.6% compared to 3Q25, reflecting fewer greenfield projects under construction. Following the commissioning of the Jacarandá project and block 3 of the Piraquê project in April and June 2026, respectively, the Company continues to plan and execute the Serra Dourada and Itatiaia projects, which have combined AAR of R$596.9 million for the 2026/2027 tariff cycle and approximately R$4.1 billion in remaining CAPEX. Of the total amount invested during the quarter, R$466.4 million was allocated to the Serra Dourada project, which reached 64% physical progress (+15 p.p. vs. 2Q26), and R$54.0 million to the Itatiaia project, which reached 35% (+2 p.p. vs. 2Q26). Accordingly, investments in greenfield projects totaled R$1,985.3 million in 9M26, a decrease of R$307.1 million ( - 13.4%) compared to 9M25. The table below presents information on the projects under construction: ¹Project Development: evolution of all activities related to the project until its energization. For more information about Greenfield projects, visit our website. Total ANEEL Actual ISA ENERGIA BRASIL Serra Dourada (Lot 1) Under construction 006/2023 ISA ENERGIA BRASIL BA/MG 337.0 3Q25 Mar-29 64% 3,752.6 2,309.9 Itatiaia (Lot 7) Environmental Licensing 012/2023 ISA ENERGIA BRASIL RJ/MG 259.9 - Mar-29 35% 2,734.8 603.4 596.9 6,487.4 2,913.3 State AAR ISA ENERGIA BRASIL Cycle 26/27 (R$ 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, as of Sep/26) Start of Construction ANEEL Deadline
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23 ri@brasil.isaenergia.com CAPITAL MARKETS Ownership Breakdown Controlled by ISA, a multilatina operating in the electric power, toll-road and telecommunications sectors, the Company had 66.5% of its outstanding shares in free float as of September 30, 2026. Data base: 09/30/2026. Stock Performance ISA ENERGIA BRASIL’s common (“ISAE3”) and preferred (“ISAE4”) shares closed 3Q26 at R$34.08 (+2.3% vs. the 2Q26 closing price) and R$27.59 ( -1.8%), respectively. During the same period, the Electric Energy Index (“IEE”) and the Ibovespa (“IBOV”) rose 4.3% and 8.3%, respectively. The Company ended 3Q26 with a market capitalization of R$21.0 billion, while ISAE4’s average daily trading volume (“ADTV”²) totaled R$104.2 million in the quarter (+27.6% vs. 2Q26). As of September 30, 2026, the Company was included in 21 indices, notably the Ibovespa, the Electric Power Index (“IEE”), the Corporate Governance Index (“IGC”), the Dividend Index (“IDIV”), and the Corporate Sustainability Index (“ISE”). In 3Q26, ISAE4 shares were also added to the MSCI universe as a Small Cap constituent of the MSCI Emerging Markets Small Cap, MSCI Emerging Markets IMI, and MSCI ACWI IMI indices, expanding the Company’s presence in global benchmarks and its potential investor universe acr oss passive, quantitative, and active emerging markets strategies. Shares % Shares % Shares % ISA Capital do Brasil S.A 230,856,832 96.93% 5,144,528 1.11% 236,001,360 33.55% Management - - - - - - Free Float 7,313,172 3.07% 460,013,216 98.89% 467,326,388 66.45% AXIA Energia 5,340,330 2.24% 130,937,325 28.15% 136,277,655 19.38% Others 1,972,842 0.83% 329,075,891 70.75% 331,048,733 47.07% Total 238,170,004 100.00% 465,157,744 100.00% 703,327,748 100.00% Shareholders ISAE3 (common) ISAE4 (preferred) Total (common + preferred) Capital markets 3Q26 3Q25 2Q26 9M26 9M25 Number of shares 703,327,748 658,882,604 658,882,604 703,327,748 658,882,604 Market Capitalization¹ (R$ billion) 21.0 18.0 20.3 21.0 18.0 ISAE3 Average volume/day (thousand shares) 3.3 2.2 2.9 3.2 2.9 ADTV ² (1,000 R$) 104 69 99 107 91 Average price (R$) 32.22 30.79 33.78 33.33 31.28 Closing price (R$) 34.08 31.32 33.30 34.08 31.32 ISAE4 Average volume/day (thousand shares) 3,834 1,855 2,794 3,032 2,238 ADTV ² (1,000 R$) 104,194 42,450 81,681 85,329 51,709 Average price (R$) 27.20 22.76 28.76 28.01 23.02 Closing price (R$) 27.59 24.67 28.11 27.59 24.67 ¹ Calculated based on the closing share price for the period. | ² Average Daily Trading Volume (“ADTV”) Evolution ISAE3 x ISAE4 x Ibovespa x IEE – 2026 (base 100) 100
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24 ri@brasil.isaenergia.com Shareholder Distributions Statutory provision: The Company’s Bylaws provide for the distribution of a minimum dividend corresponding to the greater of R$359 million and 25% of net income for the year under IFRS. Shareholder distribution practice: SA ENERGIA BRASIL adopts the practice of distributing at least 75% of regulatory net income (used as a proxy for cash generation), subject to approval at the Shareholders’ Meeting, with the possibility of paying interim dividends, while always ensuring tha t shareholder distributions are equal to or greater than the mandatory minimum dividend . The calculation basis for 2026 distributions will be pro forma regulatory net income, which excludes the One -Off Accounting Effect (Assets’ Unwinding) interests and totaled R$625.5 million in 3Q26 and R$1,157.1 million in 9M26. On September 29, 2026, the Board of Directors approved the distribution of Interest on Equity (“IoE”) related to the results for the first half of 2026, in the total amount of R$398.7 million, corresponding to R$0.566877 per share of both classes. The distribution of IoE, net of withholding income tax, was divided into three payments, each with its respective record date and ex-rights date. Record Ex-right Payment 8-Oct-26 9-Oct-26 7-Dec-26 132.9 0.188959 9-Nov-26 10-Nov-26 7-Dec-26 132.9 0.188959 25-Nov-26 26-Nov-26 7-Dec-26 132.9 0.188959 398.7 0.566877 R$ / shareEarning Type Deliberation Date Date Total¹ (R$ million) Distribution Base Interest on Equity ("IOE") 29-Sep-26 Result of the fiscal year 2026 Historical Shareholder Distributions (R$ Million)
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25 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, Soc ial and Corporate Governance Committee (“ESG”). Learn more about the sustainability commitments on the Company’s website. Highlights of the Period RECOGNIZED AMONG BRAZIL’S BEST COMPANIES ISA ENERGIA BRASIL’s inclusion in Exame magazine’s Melhores & Maiores ranking reinforces its prominent position in one of Brazil’s most established corporate assessments. The ranking combines financial and operating indicators with governance and managemen t criteria, reflecting the strength of the business and the consistency of its results. This performance demonstrates the Company’s ability to combine sustainable growth, operating efficiency and value creation for stakeholders. ETHOS RECOGNITION ISA ENERGIA BRASIL is among the 14 companies most actively engaged with Instituto Ethos and was recognized for its work in ethics, integrity, transparency and corporate sustainability. This distinction demonstrates the maturity of the Company’s governance and its responsible approach to conducting business, positively contributing to stakeholder trust, risk management and long-term value creation. USP DIVERSA: DEVELOPING TALENT FOR THE ELECTRICITY SECTOR In the third consecutive year of its partnership with USP Diversa, ISA ENERGIA BRASIL increased the number of scholarships for engineering students in socioeconomically vulnerable circumstances from 20 to 25. The support extends beyond financial assistance and includes mentoring, career guidance and professional -development initiatives. The program creates opportunities for new talent, promotes greater diversity in the electricity sector and contributes to the development of professionals prepared for the challenges of energy transition and innovation. CLIMATE MANAGEMENT AND DECARBONIZATION For the seventh consecutive year, ISA ENERGIA BRASIL received the Gold Seal from the Brazilian GHG Protocol Program, Brazil’s leading recognition for greenhouse-gas emissions management and reporting. In 2025, the Company expanded the monitoring of its value chain and achieved a cumulative 27% reduction in SF₆ emissions over four years. These advances demonstrate the evolution of the Company’s climate strategy and support its pathway toward achieving Net Zero by 2050. 2026 TRANSPARENCY AWARD ISA ENERGIA BRASIL received the 2026 Transparency Award, promoted by ANEFAC, in the category for companies with net revenue between R$5 billion and R$20 billion. The recognition highlights the quality and integrity of the Company’s financial statements, considering the level of detail in the explanatory notes, compliance with accounting standards and voluntary disclosure of relevant information, reinforcing its commitment to transparency and corporate governance.
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26 ri@brasil.isaenergia.com Sustainability KPI’s Performance of CO2 Emission Sources In 3Q26, ISA ENERGIA BRASIL remained focused on managing its operational emissions and improving asset efficiency. SF₆ leakage decreased by 16% compared to the same period of the previous year, reflecting the effectiveness of monitoring, inspection and maintenance initiatives. Year to date, however, the indicator increased by 17%, mainly due to isolated SF₆ leaks from certain assets in 2Q26, for which corrective and preventive measures were implemented. The Company also recorded an 11% reduction in electricity consumption during the quarter and an 8% decrease in 9M26, reflecting adjustments to its operational perimeter following the transfer of IE EVRECY, combined with ongoing energy-management efforts. F uel consumption decreased by 1% both in the quarter and year to date, reflecting initiatives to optimize the vehicle fleet and stationary equipment. These results reinforce ISA ENERGIA BRASIL’s commitment to operating efficiency, mitigating environmental impacts and implementing its decarbonization strategy in line with its net-zero pathway. 1 considers electricity consumption exclusively from the utility. Occupational Health and Safety (“OHS”) In 3Q26, ISA ENERGIA BRASIL strengthened its Occupational Health and Safety (“OHS”) agenda by expanding the monitoring, oversight and engagement of contractors. During the period, the Company enhanced its mechanisms for identifying and addressing non -compliance, monitoring critical issues and sharing safety best practices, with a focus on preventing incidents and continuously improving operating controls. The Company also promoted safety awareness and engagement initiatives, strengthening leadership accountability and encouraging safe behaviors throughout the organization. These initiatives support stronger OHS governance, the mitigation of operating risks and the continued development of a safety culture aligned with the safe and sustainable execution of the Company’s activities. Diversity ISA ENERGIA BRASIL’s Diversity, Equity, Inclusion and Belonging Program maintained its strategic focus in 3Q26 on developing diverse talent, strengthening inclusive leadership and fostering a culture of belonging, fully integrated into the Company’s people-management strategy. Key initiatives during the period included the continued implementation of the Empodera Talentos and Impulsiona Talentos programs, aimed at developing women and accelerating their careers, as well as the Diálogo Inclusivo workshop, which encouraged reflection on unconscious bias and its impact on relationships and decision -making. The Company also conducted awareness initiatives with leaders on the inclusion of people with disabilities, reinforcing its commitment to increasingly accessible, diverse and welcoming workplaces. The Affinity Groups continued to support program governance and advance the priority diversity, equity, inclusion and belonging agendas, contributing to employee engagement and a stronger organizational culture. These initiatives support talent attraction, development and retention, strengthen the employer brand and contribute to sustainable value creation for the business. Accidents with absense Employees 0 1 -1.0 1 3 -0.7 Third-parties Employees 10 5 1.0 23 16 0.4 Total 10 6 0.7 24 19 0.3 Accidents without absence Employees 2 0 N.A. 2 0 N.A. Third-parties Employees 2 5 -0.6 4 10 -0.6 Total 4 5 -0.2 6 10 -0.4 Accidents with Death Employees 0 0 N.A. 0 0 N.A. Third-parties Employees 0 1 -1.0 0 1 -1.0 Total 0 1 -1.0 0 1 -1.0 Accidents Frequency Rate Employees 2.4 1.2 1.0 1.2 1.3 -0.0 Third-parties Employees 2.3 1.9 0.2 1.6 1.6 -0.0 9M26 Chg (% )Category / Employee 3Q253Q26 Chg (% ) 9M25
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27 ri@brasil.isaenergia.com 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. Ethical Conduct In 3Q26, ISA ENERGIA BRASIL recorded 25 reports through the Ethics Line, representing a 39% decrease compared to 3Q25. The website remained the main reporting channel, accounting for 72% of submissions, while 56% of reports were made anonymously, reinforcing trust in the available channels. Of the reports received, 22 were concluded in the period, most of which were classified as out of scope or not confirmed after investigation and referral to the responsible areas. During the quarter, two cases were confirmed, both related to non-compliance with laws, rules and procedures. All confirmed occurrences were reviewed by the Ethics Committee, reported to the Audit and Risks Committee and handled in accordance with internal policies, resulting in the adoption of disciplinary measures and preventive actions aimed at strengthening controls and preventing recurrence. No reports related to corruption, bribery or money laundering were recorded, nor were there any legal proceedings associated with these topics. The results for the period reinforce the importance of continuously promoting an ethical culture, compliance and the proper use of integrity channels as instruments for the prevention, detection and handling of potential misconduct. 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. It received notices of violation related to the alleged use of water resources inconsistent with the applicable permit and noise levels exceeding legal lim its. The Company filed defenses and requested that the fines be canceled. No non -monetary sanctions were imposed. ¹ Significant fine: sanctions for environmental non-compliance exceeding US$10 thousand. Ethnic Diversity (%)4 Gender (%)
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28 ri@brasil.isaenergia.com SUBSEQUENT EVENTS Disposal of Significant Equity Interest On October 9, 2026, the Company received correspondence from AXIA Energia S.A. ("AXIA Energia") informing that it now holds a total of 5,340,330 common shares ("ISAE3") and 115,202,535 preferred shares ("ISAE4") issued by ISA ENERGIA BRASIL, as a result of disposals of preferred shares. These amounts represent approximately 2.24% and 24.77% of the total common and preferred shares issued by the Company, respectively, and together correspond to 17.14% of its capital stock. AXIA Energia stated that it was not a party to any contract or agreement governing the exercise of voting rights over ISA ENERGIA BRASIL’s securities. It also stated that its equity interest was held solely for investment purposes, with no intention of changing the Company’s controlling shareholders or management structure. Click here to access the full notice to the market.
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29 ri@brasil.isaenergia.com OTHER RELEVANT INFORMATION Periodic Tariff Review (PRT) – New Concessions 2026 PTR – New Concessions In June 2026, Technical Note 2026/90 (click here ) was published, revising the AAR of transmission assets whose concessions are subject to a Periodic Tariff Review (PTR) in the tariff cycle beginning in July 2026, including Concession Contract No. 005/2021 (IE Riacho Grande). The real economic repositioning index was +5.27%, resulting in a positive impact of R$ 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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30 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 unwinding 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&I”), 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. 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. AAR Cycle¹ Evolution (million)
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31 ri@brasil.isaenergia.com ¹ IE Madeira: AAR for the 2026/2027 tariff cycle reflects the asset unwinding with AXIA Energia and the consolidation of IE Madeira as a wholly owned subsidiary. Previously, the 51% interest was accounted for as a jointly controlled entity under the equity method | ² IE Garanhuns: AAR for the 2026/2027 tariff cycle reflects the asset unwinding with AXIA Energia. Previously, 51% interest was accounted for as a jointly controlled entity under the equity method; following the transaction, IE Garanhuns is no longer part of the Company’s asset base. 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% Controlled Subsidiaries 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 1,263 77 6 5 -1 1,723 -54 1,669 1,263 36% 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% 013/2009 Lote D 408 19 0 0 0 428 -18 410 408 5% 015/2009 Lote F 352 17 0 0 0 369 -15 354 352 5% Consolidated ISA ENERGIA BRASIL in operation 5,388 272 129 5 -32 6,135 -4 6,131 5,388 14% Jointly Controlled Subsidiaries AAR 25/26 Cycle AAR 26/27 Cycle PA AAR 26/27 Cycle REH 3.348 DSP 2268 Total with PA Subsidiaries (non-consolidated) in operation 828 31.6 0 0 0 702 -24 677 828 -15% IE Paraguaçu (50%) 003/2017 Paraguaçu IPCA 162 7.7 0 0 0 170 -6 164 162 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 5% IE Garanhuns (51%)² 022/2011 Garanhuns IPCA 158 0.0 0 0 0 0 0 0 0 0% Participation ISA ENERGIA BRASIL 415 16 0 0 0 351 -12 339 415 -16% ISA ENERGIA BRASIL in operation 5,803 287 129 5 -32 6,485 -16 6,469 5,803 12% PROJECTS UNDER CONSTRUCTION AAR 25/26 Cycle AAR 26/27 Cycle PA AAR 26/27 Cycle REH 3.348 DSP 2268 Total com PA Controlled Subsidiaries 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) 6,373 314.4 129.1 5 -32 7,082 -16 7,066 6,373 11% AAR 25/26 Cycle Chg % ex-PAConcessionaire Contract Project Index Inflation ISA ENERGIA BRASIL 059/2001 IPCA 63 R&I RTP Other¹ RTP Other² AAR 25/26 Cycle Chg % ex-PA IEMG Concessionaire (R$ million) Contract Project Index Inflation R&I IE Jaguar 6 IE Tigabi IE Madeira¹ IPCA IE SUL IE Itapura IE Jaguar 8 RTP Other² AAR 25/26 Cycle Chg % ex-PA Concessionaire (R$ million) Contract Project Index Inflation R&I Concessionaire (R$ million) Contract Project Index Inflation R&I RTP Other² AAR 25/26 Cycle Chg % ex-PA ISA ENERGIA BRASIL
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32 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 near 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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33 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 judicial decisions altering one or more conditions of the RBSE payment be disregarded. Any new judicial decisions, depending on their content and scope, if not reversed in a timely manner, may or may no t 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.
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34 ri@brasil.isaenergia.com 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 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, pursuant to the preliminary injunction issued by the 49th Labor Court, SEFAZ has transferred to the Company an amount below that required to make payments to retirees (approximately 70%). ISA ENERGIA BRASIL has therefore funded the shortfall to ensure full payment of retirees’ benefits (approximately 30%). The Company is seeking reimbursement of these supplementary payments through legal action against SEFAZ. The court ruled in favor of the Company on appeal. In August 2017, SEFAZ filed a Special Appeal with the Superior Court of Justice (“STJ”), which was pending an admissibility review. As of September 30, 2026, the amount recognized on the Company’s balance sheet remained at approximately R$2.9 billion, net of the provision for credit losses recognized in 2013. Between August 2018 and March 2019, ISA ENERGIA BRASIL received full transfers from SEFAZ pursuant to a preliminary court order, which was subsequently suspended by the STJ pending judgment of SEFAZ’s appeal. In March 2024, SEFAZ’s appeal was decided by a single justice of the STJ, who ordered the case to be remanded to the São Paulo State Court of Appeals (“TJSP”). The TJSP must define in its decision each party’s respective responsibility for the installments and components comprising the supplementary pension payments. ISA ENERGIA BRASIL was ordered to continue paying the disallowed amounts, as it has been since 2005, until a final, unappealable decision is issued. In October 2024, by agreement of the parties to pursue settlement discussions, the STJ stayed the collection proceedings for 180 days. On May 22, 2025, an initial mediation hearing was held at the STJ Judicial Center for Dispute Resolution (“CEJUSC/STJ”), with the participation of the São Paulo State Attorney General’s Office, and the stay was renewed for an additional 180 days. In addition to the initial hearing, six hearings were held between August and November 2025. In 2026, four mediation hearings were held on February 3, April 4, June 16 and August 26. The next mediation hearing will take place in 2027, with the specific date yet to be determined. The attempt to reach an amicable settlement does not prejudice the Company’s rights or alter any court decision currently in effect or the existing payment flow. If the settlement attempt is unsuccessful, the proceedings will resume as before. The Company continues its efforts to preserve the favorable decision on the merits obtained before the TJSP. The amount recognized by the Company under “Amounts Receivable – State Treasury Department” totaled R$2,874.9 million as of September 30, 2026. In addition, the Company maintains a provision of R$516.3 million, recorded in 2013 due to the extension of the expected recovery period for a portion of the receivables from the State of São Paulo and procedural developments at that time. The amounts mentioned above are stated at historical value and do not include any monetary adjustment or other form of restatement.
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35 ri@brasil.isaenergia.com GLOSSARY ADTV (Average Daily Traded Volume) – The average daily financial volume traded for an asset over a given period. ANEEL (Brazilian Electricity Regulatory Agency) – The government agency responsible for regulating and overseeing electricity generation, transmission, distribution and trading in Brazil. CAAE (Annual Cost of Electricity Assets) – The portion of revenue associated with the return on investments in electricity assets, comprising the return on capital and the Regulatory Reinstatement Quota (“QRR”). CAGR (Compound Annual Growth Rate) – The compound annual growth rate. CAOM (Administration, Operation and Maintenance Costs) – The portion of revenue intended to cover the administration, operation and maintenance costs of facilities, including components established by applicable regulations. It may be divided into (i) O&M revenue, intended to cover costs and expenses such as payroll, maintenance and other expenditures; and (ii) revenue intended to cover the costs of movable and immovable facilities (“CAIMI”). CAPEX (Capital Expenditures) – Investments in the acquisition, implementation, expansion, modernization or improvement of assets. CCEE (Electricity Trading Chamber) – Operates under authorization from the granting authority and under ANEEL’s regulation and oversight to facilitate electricity purchase and sale transactions among CCEE participants. CDE (Energy Development Account) – A sector charge used to fund public policies for the electricity sector under applicable regulations. Organic growth – Growth arising from investments in existing assets and concessions, including retrofitting and improvements. CVM (Brazilian Securities and Exchange Commission) – A government agency linked to the Ministry of Finance that oversees, regulates, disciplines and develops Brazil’s securities market. EBITDA (Earnings Before Interest, Taxes, Depreciation and Amortization) – Earnings before interest, taxes, depreciation and amortization. Regulatory charges – Amounts collected in connection with the provision of transmission services and allocated to purposes established under sector regulations; where applicable, they do not constitute operating revenue of the transmission company. Commissioning – The stage at which the facilities or equipment of a transmission project are energized in accordance with applicable procedures, whether for a retrofitting, improvement or greenfield project. EPE (Energy Research Office) – A state-owned company responsible for studies and research supporting the planning of Brazil’s energy sector. 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 the ground up. IBBC (Bovespa BR+ Cap 5% B3 Index) – An index designed to reflect the performance of highly tradable and representative assets, limiting each asset’s individual weight in the portfolio to 5%. IBBE (Bovespa BR+ Equal Weight B3 Index) – An index in the Ibovespa BR+ family structured with equal weighting among its portfolio assets. IBBR (Bovespa B3 BR+ Index) – An index designed to reflect the performance of a portfolio comprising eligible assets issued by Brazilian companies. IBEP (Bovespa B3 Private Companies Index) – An index designed to reflect the performance of eligible assets issued by privately controlled companies. IBEW (Bovespa B3 Equal Weight Index) – An index comprising eligible Ibovespa assets with equal weighting among portfolio components.
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36 ri@brasil.isaenergia.com IBOV B3 (Bovespa B3 Index) – The main performance indicator for shares traded on B3, comprising leading companies in Brazil’s capital markets. Its portfolio includes shares that collectively represent 85% in descending order of Tradability Ratio, subject to a 90% buffer; have a 95% trading-session presence; represent at least 0.1% of financial volume in the standard-lot cash market; and are not penny stocks. IBRA (Broad Brazil Index) – An indicator of the average performance of all assets traded in B3’s standard-lot cash market that meet minimum liquidity and trading-session presence requirements, providing a broad view of the equity market. IBRX100 (Brazil 100 Index) – An indicator of the average performance of the 100 most tradable and representative assets in Brazil’s equity market. IBSD (Bovespa Smart Dividend Index) – An indicator of the average performance of listed companies that stand out in terms of shareholder remuneration through dividends and interest on equity. IBST (Bovespa BESST Dividend Index) – An indicator of the average performance of highly tradable and representative assets that stand out for shareholder remuneration within specific sectors. IBVL (Bovespa Smart Low Volatility B3 Index) – An indicator of the average performance of highly tradable and representative assets with lower volatility in daily returns. ICO2 (Carbon Efficient Index) – An index that considers companies’ greenhouse-gas emissions efficiency and emissions-management practices. Participation in the B3 ICO2 demonstrates a company’s commitment to emissions efficiency and management practices that support the transition to a low-carbon economy. IDIV (Dividend Index) – An index designed to reflect the performance of assets that stand out for shareholder remuneration through dividends and interest on equity. IDVR (B3 Diversity Index) – An index designed to reflect the performance of companies selected based on diversity-related criteria. IE – Interligação Elétrica. IEE (Electric Power Index) – A B3 sector index designed to measure the performance of the electricity sector. IENS (Non-Supplied Energy Index) – An indicator associated with energy not supplied due to system interruptions. IFES (ESG Infrastructure Index) – An indicator of the average performance of the most tradable and representative assets in the Utilities and Industrial Goods sectors. IGC (Special Corporate Governance Stock Index) – An indicator of the average performance of securities issued by companies listed on B3’s Novo Mercado or Levels 1 or 2. IGCT (Corporate Governance Trade Index) – An indicator of the average performance of securities issued by companies included in the IGC. IPCA (Extended National Consumer Price Index) – Brazil’s official inflation index, calculated by IBGE. ISE B3 (Corporate Sustainability Index) – An indicator of the average performance of securities issued by companies selected for their recognized commitment to corporate sustainability. IOE (Interest on Equity) – A form of shareholder remuneration subject to the tax treatment established under applicable law. Electricity Transmission Auctions – Competitive bidding processes established by the MME and ANEEL to award concessions for transmission lines and substations in Brazil. M&A (Mergers and Acquisitions) – Mergers and acquisitions. Improvement – The installation, replacement or refurbishment of equipment at existing transmission facilities, or adaptations to such facilities, intended to maintain the adequate provision of public electricity -transmission services. MLCX (MidLarge Cap Index) – An indicator of the average performance of securities issued by B3’s largest companies by market capitalization. MME (Ministry of Mines and Energy) – The federal government body responsible for formulating public policies for the energy and mining sectors.
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37 ri@brasil.isaenergia.com O&M (Operation and Maintenance) – Activities related to operating and maintaining assets and facilities. ONS (National Electricity System Operator) – The entity responsible for coordinating and controlling the operation of electricity generation and transmission within the SIN. Other Revenue – Revenue associated with activities additional to the primary provision of public transmission services and subject to applicable regulatory treatment. PA (Adjustment Portion) – A component used to offset collection differences or other adjustments related to prior periods under applicable regulations. PMSO (Personnel, Materials, Services and Other) – Operating costs and expenses related to personnel, materials, third-party services and other items. PROINFA (Program of Incentives for Alternative Electricity Sources) – A program established to encourage the participation of alternative renewable sources in Brazil’s electricity generation mix. PV (Variable Portion) – A component associated with the availability and capacity of transmission facilities that may reduce revenue due to outages and other events specified under applicable regulations. R&D (Research and Development) – Research and development activities and investments under applicable regulations. QRR (Regulatory Reinstatement Quota) – A regulatory component associated with recovering capital invested in assets over their regulatory useful lives. AAR (Annual Allowed Revenue) – Revenue established to remunerate the provision of public electricity- transmission services under concession agreements and applicable regulations. It may include additional revenue related to the commissioning of new authorized investments. RB (Basic Grid) – SIN transmission facilities owned by public electricity-transmission concessionaires and defined according to criteria established under ANEEL regulations. RBNI (Basic Grid – New Investments) – The portion of AARassociated with newly authorized Basic Grid facilities whose revenue is established by a specific resolution. RBSE (Existing System Basic Grid) – The portion of AAR associated with Basic Grid facilities listed in the appendix to Resolution No. 166 of May 31, 2000. Retrofitting – The installation, replacement or refurbishment of equipment at existing transmission facilities, or adaptations to such facilities, intended to increase transmission capacity, SIN reliability or useful life, or to connect users. RGR (Global Reversion Reserve) – A sector charge established for the purposes specified under electricity-sector legislation. RTP (Periodic Tariff Review) – The periodic process of reviewing the revenue components of transmission concessions under concession agreements and applicable regulations. SIN (National Interconnected System) – The facilities and equipment that enable electricity supply across Brazil’s electrically interconnected regions under applicable regulations. TCU (Federal Court of Accounts) – The body responsible for external oversight of the federal public administration under applicable law. TFSEE (Electricity Services Inspection Fee) – A fee used to fund the oversight of electricity services under applicable law. TUST (Electricity Transmission System Use Tariff) – A tariff paid by distributors, generators and free and special consumers for using the Basic Grid and DIT facilities. It is adjusted annually based on (i) inflation and (ii) new revenue associated with commissioned projects. UTIL B3 (Utilities Index) – An indicator of the average performance of the most tradable and representative assets in the utilities sector, including electricity, water and sanitation, and gas.
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38 ri@brasil.isaenergia.com ATTACHMENTS Attachment I – Greenfield Projects since 2016 | Growth Click here to access the spreadsheet. 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-19 170.6 208.3 ✓ 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 1,063.9 ✓ 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-21 641.4 458.8 ✓ 1Q21 100% 100% 3Q22 Minuano (Lot 1) 6 001/2020 Evrecy 100% RS 55.5 mar-25 jan-20 681.6 738.2 ✓ 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 3,867.7 ✓ 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 2,256.9 ü 3T25 96% 64% - Itatiaia (Lot 7) 012/2023 ISA ENERGIA BRASIL 100% RJ/MG 259.9 mar-29 immediate 2,300.6 587.4 4T26 1T27 89% 35% - 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 12,619.3Total (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 09/30/2026 (R$ million) 001/2023 (jun/2023) 002/2019 (dec/2019) Land Development4 Projects Development5Project Deadline ANEEL Entry in Commercial Operation 013/2015 (oct/2016) 005/2016 (apr/2017) 002/2018 (jun/2018)
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39 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) 3Q26 3Q25 Chg (% ) Retroffiting Projects 578.5 437.9 32.1% Greenfield Projects 524.9 767.5 -31.6% 100% ISA ENERGIA BRASIL 525.4 756.8 -30.6% Piraquê 1.6 503.6 -99.7% Riacho Grande 0.0 70.0 -100.0% Serra Dourada 466.4 124.0 276.0% Itatiaia 54.0 30.2 79.0% Jacarandá 0.0 30.3 -100.0% Minuano 0.6 -1.3 N.A Biguaçu 2.8 0.0 N.A Jointly-controlled subsidiaries -0.5 10.8 -105.1% Ivaí -0.5 0.0 N.A Total 1,103.3 1,205.4 -8.5% Consolidated + Jointly-controlled
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40 ri@brasil.isaenergia.com Annex III – Regulatory Balance Sheet Assets (R$ thousand) 30/09/2026 30/09/2025 CURRENT Cash and Cash Equivalents 441,736 1,356,062 Financial Investments 2,526,363 808,924 Accounts receivable - Concessionaires and 604,510 469,745 Inventory 119,313 48,054 Recoverable taxes and contributions 295,197 229,311 Derivative instruments 0 37,384 Credit with controlled parties 3,587 126,061 Prepaid Expenses 39,404 6,061 Restricted cash 0 0 Others 391,357 165,619 4,421,467 3,247,221 NON-CURRENT Long-Term Assets Restricted cash 79,403 18,888 Accounts receivable - Concessionaires and 147,036 205,383 Accounts Receivable from the State Finance 2,874,979 2,760,806 Deferred income taxes and social contribution 0 0 Pledges and Escrow 46,551 46,049 Derivative financial instruments 60,469 20,406 Others 105,299 76,525 3,313,737 3,128,057 Investments 43,159 1,366,474 Imobilized 25,850,576 20,832,086 Intangible 4,321,430 1,819,316 30,215,165 24,017,876 33,528,902 27,145,933 Total Assets 37,950,369 30,393,154 Consolidated
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41 ri@brasil.isaenergia.com Liabilities and Shareholders' Equity (R$ thousand) 30/09/2026 30/09/2025 CURRENT Loans and Financing 257,762 90,082 Debentures 373,220 496,001 Leasing 16,721 18,677 Derivative financial instruments 9,212 2,916 Suppliers 252,088 254,342 Taxes and social charges to be collected 269,226 213,752 Deferred Income Tax and Social Contribution 0 0 Regulatory charges to be collected 50,880 66,723 Interest on Shareholders' Equity / Dividends to 419,812 422,540 Provisions 93,802 79,962 Amounts Payable - Funcesp 834 1,335 Capex - Provisions 303,879 210,460 Others 14,227 30,299 2,061,663 1,887,089 NON-CURRENT Long-Term Liabilities Loans and Financing 1,035,325 669,117 Debentures 18,096,273 14,696,513 Leasing 26,086 36,959 Derivative financial instruments 15,163 17,312 Suppliers 3,868 3,456 Diferred PIS and COFINS 20,717 25,773 Deferred income taxes and social contribution 2,246,491 1,524,834 Regulatory charges to be collected 66,391 35,404 Provisions 175,410 157,457 Obligations connected to concession service 891,705 850,307 Others 396 334 22,577,825 18,017,466 SHAREHOLDER'S EQUITY Share Capital 4,790,020 3,590,020 Follow on Costs -20,837 0 Capital Reserves 666 666 Income Reserves 5,618,242 3,742,461 Revaluation reserve 2,374,108 2,493,015 Other Comprehensive Results 88,362 97,571 Additional Dividends Proposed 279,322 279,322 13,129,883 10,203,055 Non-controlling shareholders' share of investment funds 180,998 285,544 13,310,881 10,488,599 Total Liabilities and Shareholders' Equity 37,950,369 30,393,154 Consolidated
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42 ri@brasil.isaenergia.com Annex IV – Regulatory Income Statement ¹ Includes costs and expenses related to the private pension plan. Income Statement (R$ thousand) 3Q26 3Q25 Chg (% ) 9M26 9M25 Chg (% ) Gross Revenue 1,721,709 1,250,582 37.7% 4,536,355 3,718,702 22.0% Availability of Electric Network 1,710,580 1,239,400 38.0% 4,503,747 3,684,824 22.2% Others 11,129 11,182 -0.5% 32,608 33,878 -3.7% Deductions from the Operational Revenue -211,046 -178,249 18.4% -556,054 -485,886 14.4% T axes and Contributions on Revenue -149,279 -105,611 41.3% -391,764 -319,498 22.6% Regulatory charges -61,767 -72,638 -15.0% -164,290 -166,388 -1.3% Net Revenue 1,510,663 1,072,333 40.9% 3,980,301 3,232,816 23.1% Costs and Operational Expenses -462,704 -355,245 30.2% -1,248,564 -1,164,048 7.3% Personnel -117,093 -102,391 14.4% -335,145 -316,306 6.0% Material -6,277 -5,647 11.2% -17,241 -16,870 2.2% Services -83,512 -54,050 54.5% -191,448 -146,005 31.1% Depreciation -250,970 -167,561 49.8% -642,551 -591,342 8.7% Others -4,852 -25,596 -81.0% -62,178 -93,525 -33.5% Result of Service 1,047,959 717,088 46.1% 2,731,737 2,068,768 32.0% Financial Results -348,094 -293,134 18.7% -1,469,918 -996,252 47.5% Income from Financial Investments 92,495 90,045 2.7% 212,820 243,406 -12.6% Result of Liquid Monetary Variation 11,475 -57,915 n.a -430,924 -345,670 24.7% Asset and Liability Interest 25 -152 n.a 191 -2,967 n.a Interest/Charges on loans -428,385 -336,504 27.3% -1,207,141 -933,258 29.3% Others -23,704 11,392 n.a -44,864 42,237 n.a Operational Result 699,865 423,954 65.1% 1,261,819 1,072,516 17.7% Equity Income 34,153 100,365 -66.0% 197,208 266,983 -26.1% Other Operational Revenues/Expenses 1,891,155 3,833 49238.8% 1,803,863 -58,835 n.a Results before Taxes 2,625,173 528,152 397.0% 3,262,890 1,280,664 154.8% Income Tax and Social Contribution on -712,529 39,853 n.a -793,806 -91,093 771.4% Current 27,387 38,604 -29.1% -108,113 -45,021 140.1% Deferred -739,916 1,249 n.a -685,693 -46,072 1388.3% Consolidated Income/Losses of the Period with the Participation of the Non Controlling Shareholder 1,912,644 568,005 236.7% 2,469,084 1,189,571 107.6% Participation of Non Controlling Shareholder -7,836 -17,976 -56.4% -32,677 -46,548 -29.8% Net Income/Loss Consolidated in the Period 1,904,808 550,029 246.3% 2,436,407 1,143,023 113.2% Consolidated
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43 ri@brasil.isaenergia.com Annex V – Indirect Cash Flow – Regulatory¹ ¹ The indirect cash flow statement under the regulatory methodology classifies cash outflows related to greenfield, brownfield, and Retrofitting and Improvement projects as investing activities. Cash Flow of operational activities (R$ thousand) 9M26 9M25 Cash generated by operational activities 3,218,830 2,661,340 Net Income 2,469,084 1,189,571 Employee benefit - actuarial deficit 0 0 Deferred PIS and COFINS -5,056 -13,159 Depreciation and amortization 709,810 656,061 Deferred income taxes and social contribution 684,466 46,070 Provision for Lawsuit Liabilities -7,396 -47,676 Residual value of fixed/intangible assets 54,352 31,711 Tax benefit - incorporated goodwill 28 27 Result of equity income -256,469 -266,981 Income from financial investments -92,156 -104,762 Interest and exchange variations on loans, financing and debentures 1,624,187 1,264,876 Interest and monetary and exchange variations on assets and liabilities -22,825 -44,432 Bargain Purchase Gain on the Acquisition of an Equity Interest -1,866,294 0 Loss on Disposal of Equity Interest -72,055 0 Financial Instruments 31,831 -3,418 Transactions with non-controlling shareholders -32,677 -46,548 Assets Variation -362,135 648,097 Restricted cash 0 0 Accounts receivable - Concessionaires and Permissionaires -11,411 157,976 Inventories -10,757 -9,242 Accounts Receivable from the State Finance Secretariat -114,173 -143,176 Recoverable taxes and contributions -43,438 124,171 Prepaid Expenses -28,590 -6,016 Pledges and Escrow 1,110 -188 Credit with subsidiaries 0 0 Others -154,876 524,572 Liabilities Variation -21,759 -92,477 Suppliers -13,969 26,776 Taxes and social charges to be collected 111,763 189,651 Labor obligations 10,223 11,456 Tax payment -173,758 -136,660 Regulatory charges to be collected -29,471 13,784 Provisions 258,221 -4,896 Amounts payable to Vivest -501 435 Global Reversal Reserve - RGR -1,860 -1,861 Obligations linked to the concession of the service 41,400 -14,873 Post-employment benefit - actuarial liability 0 0 Others -223,807 -176,289 Net cash generated in operational activities 2,834,936 3,216,960 Investments Activites Cash Flow -5,780,374 -4,336,821 Restricted cash -676 874 Financial Investments -4,051,984 -5,093,394 Redemptions of financial investments 2,476,483 4,115,325 Fixed Assets -3,447,539 -3,359,626 Investments -1,415,225 0 Caixa acquired a business combination 462,362 0 Received dividends 196,205 0 Cash used in financing activities 2,031,112 -1,075,710 New loans and debentures 6,285,083 2,007,347 Loan and debentures payments (principal) -3,769,540 -1,030,172 Loan and debentures payments (interest) -926,199 -719,616 Lease Payments (principal and interest) -18,107 -11,094 Derivative instruments -55,498 13,660 Capital Contribution 1,200,000 0 Share Issuance Costs -20,837 0 Paid dividends and interest on equity -663,790 -1,335,835 Net variation in Cash and Cash Equivalents -914,326 -2,195,571 Opening Balance of Cash and Cash Equivalents 1,356,062 2,914,747 Closing Balance of Cashand Cash Equivalents 441,736 719,176 Closing Balance of Cash and Cash Equivalents -914,326 -2,195,571 Consolidated
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44 ri@brasil.isaenergia.com Annex VI – Regulatory Result of Non-Consolidated Companies Income Statement (R$ thousand) Gross Operational Revenue 29,668 29,772 -0.3% 89,604 86,681 3.4% Operational Revenue Deductions -3,085 -3,167 -2.6% -9,217 -9,121 1.1% Net Operational Revenue 26,583 26,605 -0.1% 80,387 77,560 3.6% Costs and Expenses -1,571 -765 105.4% -4,314 -4,119 4.7% Depreciation -2,722 -2,721 0.0% -8,165 -8,163 0.0% EBITDA 25,012 25,840 -3.2% 76,073 73,441 3.6% Gross Profit 22,290 23,119 -3.6% 67,908 65,278 4.0% Financial Result -8,511 -7,179 18.6% -25,456 -5,850 335.1% Other Revenues and Expenses 0 0 N.A. 0 0 N.A. Income before IR & CSLL 13,779 15,940 -13.6% 42,452 59,428 -28.6% IR & CSLL* -2,253 -1,797 25.4% -5,297 -6,411 -17.4% Net Income 11,526 14,143 -18.5% 37,155 53,017 -29.9% ISA ENERGIA BRASIL Particip. (50% ) on EBITDA 12,506 12,920 -3.2% 38,037 36,721 3.6% ISA ENERGIA BRASIL Particip. (50% ) on Net Income 5,763 7,072 -18.5% 18,578 26,509 -29.9% IE AIMORÉS 3Q26 3Q25 Chg (% ) 9M26 9M25 Chg (% ) Income Statement (R$ thousand) Gross Operational Revenue 46,840 45,303 3.4% 135,904 129,348 5.1% Operational Revenue Deductions -4,863 -4,757 2.2% -13,915 -14,122 -1.5% Net Operational Revenue 41,977 40,546 3.5% 121,989 115,226 5.9% Costs and Expenses -2,195 -1,626 35.0% -6,443 -5,994 7.5% Depreciation -4,657 -4,658 0.0% -13,972 -13,962 0.1% EBITDA 39,782 38,920 2.2% 115,546 109,232 5.8% Gross Profit 35,125 34,262 2.5% 101,574 95,270 6.6% Financial Result -15,699 -13,663 14.9% -46,254 -9,957 364.5% Other Revenues and Expenses 0 0 N.A. 0 0 N.A. Income before IR & CSLL 19,426 20,599 -5.7% 55,320 85,313 -35.2% IR & CSLL* -2,851 -2,547 11.9% -3,508 -8,591 -59.2% Net Income 16,575 18,052 -8.2% 51,812 76,722 -32.5% ISA ENERGIA BRASIL Particip. (50% ) on EBITDA 19,891 19,460 2.2% 57,773 54,616 5.8% ISA ENERGIA BRASIL Particip. (50% ) on Net Income 8,288 9,026 -8.2% 25,906 38,361 -32.5% 9M26 9M25 Chg (% )3Q26 3Q25 IE PARAGUAÇU Chg (% )
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45 ri@brasil.isaenergia.com Income Statement (R$ thousand) Gross Operational Revenue 71,517 103,409 -30.8% 294,346 313,371 -6.1% Operational Revenue Deductions -11,918 -10,862 9.7% -35,289 -32,873 7.3% Net Operational Revenue 59,599 92,547 -35.6% 259,057 280,498 -7.6% Costs and Expenses -4,907 -6,278 -21.8% -15,714 -16,292 -3.5% Depreciation -12,534 -15,243 -17.8% -40,546 -42,329 -4.2% EBITDA 53,518 86,269 -38.0% 241,964 264,256 -8.4% Gross Profit 42,158 71,026 -40.6% 202,798 221,878 -8.6% Financial Result -70,668 -31,264 126.0% -203,455 -148,136 37.3% Other Revenues and Expenses -1,174 0 N.A. -1,380 49 n.a Income before IR & CSLL -29,683 39,762 n.a -2,036 73,791 n.a IR & CSLL* 43,092 -13,523 n.a 33,692 -25,092 n.a Net Income 13,409 26,240 -48.9% 31,656 48,699 -35.0% ISA ENERGIA BRASIL Particip. (50% ) on EBITDA26,759 43,135 -38.0% 120,982 132,128 -8.4% ISA ENERGIA BRASIL Particip. (50% ) on Net Income6,704 13,120 -48.9% 15,828 24,349 -35.0% IE IVAÍ 9M25 Chg (% )9M26Chg (% )3Q26 3Q25 Income Statement (R$ thousand) Gross Operational Revenue 148,025 178,484 -17.1% 519,854 529,400 -1.8% Operational Revenue Deductions -19,866 -18,786 5.7% -58,421 -56,116 4.1% Net Operational Revenue 128,159 159,698 -19.7% 461,433 473,284 -2.5% Costs and Expenses -8,673 -8,669 0.0% -26,471 -26,405 0.3% Depreciation -19,913 -22,622 -12.0% -62,683 -64,454 -2.7% EBITDA 118,312 151,029 -21.7% 433,583 446,929 -3.0% Gross Profit 99,573 128,407 -22.5% 372,280 382,426 -2.7% Financial Result -94,878 -52,106 82.1% -275,165 -163,943 67.8% Other Revenues and Expenses -1,174 0 N.A. -1,380 49 n.a Income before IR & CSLL 3,522 76,301 -95.4% 95,736 218,532 -56.2% IR & CSLL* 37,988 -17,867 n.a 24,887 -40,094 n.a Net Income 41,510 58,435 -29.0% 120,623 178,438 -32.4% ISA ENERGIA BRASIL Particip. (50% ) on EBITDA59,156 75,515 -21.7% 216,791 223,464 -3.0% ISA ENERGIA BRASIL Particip. (50% ) on Net Income20,755 29,217 -29.0% 60,311 89,219 -32.4% AIE (IE IVAÍ + IE PARAGUAÇU + IE AIMORÉS) 9M26 9M25 Chg (% )Chg (% )3Q26 3Q25
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46 ri@brasil.isaenergia.com Annex VII – Covenants (R$ million) The main financial commitments under the financing agreements (financial covenants) to which ISA ENERGIA BRASIL is subject are set out below: The financing agreements with BNDES (valid until their maturity in 2041) must comply with the following maximum financial ratios: Net Debt/BNDES Adjusted EBITDA ≤ 3.0 and Net Debt/(Net Debt + Shareholders' Equity) ≤ 0.6. The balance of these financings wit h BNDES as of 09/30/2026 totals R$649.9 million, and the agreements allow for prepayment. The ratios are measured at the end of each fiscal year. For purposes of calculating and demonstrating these ratios, the Company must consolidate all subsidiaries and jointly controlled entities (proportionally to its interest), provided that it holds an equity interest equal to or greater than 10%. EBITDA is calculated in accordance with the methodology defined in the agreements. The most recent measurement was based on information as of December 31, 2025, and the Company and its subsidiaries met the requir ements related to restrictive covenants. The next measurement will be made with data as of December 31, 2026. In November 2025, the Company received a letter from BNDES formalizing its prior consent and its waiver of the declaration of early maturity of certain financing agreements, in the context of monitoring the financial ratios for fiscal year 2025. For management purposes, the Net Debt/EBITDA ratio under this methodology is calculated quarterly and stood at 3.50x in 3Q26. Net Debt 09/30/26 18,311.6 EBITDA LTM 5,239.1 Net Debt/EBITDA 09/30/26 3.50 Shareholders' Equity 09/30/26 24,033.6 Net Debt/(Net Debt + Shareholders' Equity) 09/30/26 0.43 (annual verification) BNDES
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47 ri@brasil.isaenergia.com Annex VIII – Balance Sheet – IFRS Assets (R$ thousand) 30/09/2026 30/09/2025 CURRENT Cash and cash equivalents 441,736 1,356,062 Financial investments 2,526,363 808,924 Concession Asset 5,255,908 4,106,084 Inventories 121,914 72,704 Taxes and contributions to compensate 295,197 229,311 Derivative instruments 0 37,384 Credit with related parties 2,559 126,579 Prepaid expenses 39,404 6,061 Restricted Cash 0 0 Advance to suppliers 0 0 Others 768,706 344,330 9,451,787 7,087,439 NON-CURRENT Long-term Receivables Restricted Cash 79,403 18,888 Concession Asset 41,790,962 32,325,214 Accounts Receivable from the State Finance 2,874,979 2,760,806 Pledges and Escrow 46,551 46,049 Inventories 137,129 94,871 Derivative instruments 60,469 20,406 Others 105,299 76,525 45,094,792 35,342,759 Investments 1,335,629 4,154,815 Imobilized 159,998 180,126 Intangible 96,724 436,233 1,592,351 4,771,174 46,687,143 40,113,933 Total Assets 56,138,930 47,201,372 Consolidated
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48 ri@brasil.isaenergia.com Liabilities and Shareholders' Equity (R$ thousand) 30/09/2026 30/09/2025 CURRENT Loans and financing 257,762 90,082 Debentures 373,220 496,001 Leasing 16,721 18,677 Derivative financial instruments 9,212 2,916 Suppliers 251,102 254,445 Taxes and social charges to be collected 268,557 213,325 Regulatory Charges to be collected 50,880 66,723 Interest on Shareholders' Equity/Dividends 419,812 422,540 Labor obligations 93,802 79,962 Amounts Payable - Vivest 834 1,335 Others 318,102 240,765 2,060,004 1,886,771 NON-CURRENT Long-term Liabilities Loans and financing 1,035,325 669,117 Debentures 18,096,273 14,696,513 Leasing 26,086 36,959 Derivative financial instruments 15,163 17,312 Suppliers 3,868 3,456 Provision for Contingencies 194,532 163,035 Deferred PIS and COFINS 3,933,329 2,966,130 Deferred Income Tax and Social Contribution 6,672,253 5,287,595 Regulatory Charges to be collected 66,391 35,404 Others 2,124 2,069 Total long-term liabilities 30,045,344 23,877,590 NET EQUITY Shareholders' Equity 4,790,020 3,590,020 Follow On Cost - 20,837 - Capital Reserves 666 666 Profits Reserve 18,714,837 17,183,674 Other comprehensive results 88,576 97,785 Proposed additional dividends 279,322 279,322 23,852,584 21,151,467 Non-controlling shareholders' share of investment funds 180,998 285,544 24,033,582 21,437,011 Total Liabilities and Shareholders' Equity 56,138,930 47,201,372 Consolidated
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49 ri@brasil.isaenergia.com Annex IX – Income Statement – IFRS Income Statement (R$ thousand) 3Q26 3Q25 Chg (% ) 9M26 9M25 Chg (% ) Gross Operational Revenue 2,630.1 2,881.9 -8.7% 8,334 7,196 15.8% Infrastructure Revenue 1,428.8 1,516.7 -5.8% 4,327 4,218 2.6% O&M Gross Revenue 464.0 294.2 57.7% 1,170 946 23.7% Remuneration of concession assets 726.6 1,060.8 -31.5% 2,808 2,003 40.1% Other Revenues 10.7 10.1 5.8% 30 28 4.9% Deductions from Operational Revenue -296.4 -322.9 -8.2% -892 -792 12.7% Net Operational Revenue 2,333.7 2,559.0 -8.8% 7,442 6,404 16.2% Operational Costs and Expenses -1,339.9 -1,396.3 -4.0% -4,041 -4,028 0.3% Personnel -140.6 -126.1 11.5% -469 -379 23.6% Materials -382.8 -453.5 -15.6% -1,421 -1,444 -1.6% Services -755.8 -744.7 1.5% -1,935 -1,969 -1.7% Depreciation -14.9 -8.7 71.5% -33 -26 29.0% Others -45.8 -63.2 -27.6% -182 -210 -13.4% Revenues – Periodic Tariff Reset (RTP) 49.0 -6.9 -812.9% 49 159 -69.3% Service Income 1,042.8 1,155.8 -9.8% 3,450 2,535 36.1% Financial Income -348.4 -293.3 18.8% -1,471 -997 47.5% Income from Financial Investments 92.5 90.0 2.7% 213 243 -12.6% Result of Liquid Monetary Variation 11.1 -50.5 -122.1% -432 -291 48.1% Interest costs 0.0 -0.2 -116.4% 0 -3 -106.4% Interest/Charges on loans -428.4 -336.5 27.3% -1,207 -933 29.3% Others -23.7 3.8 -722.6% -45 -12 260.3% Operational Result 694.3 862.5 -19.5% 1,980 1,538 28.7% Equity Income 59.9 109.5 -45.3% 359 404 -11.0% Other Operating Revenues/Expenses 283.8 14.4 1875.5% 290 15 1878.0% Earnings Before Taxes 1,038.0 986.4 5.2% 2,629 1,957 34.3% Income tax and Social Contribution on Earnings -116.3 -183.6 -36.7% -384 -197 95.2% Current 27.4 38.6 -29.1% -111 -45 146.1% Deferred -143.7 -222.2 -35.3% -274 -152 80.1% Consolidated Profit/Loss 921.7 802.8 14.8% 2,244 1,760 27.5% Non-Controlling Shareholder's Stake -7.8 -18.0 -56.4% -33 -47 -29.8% Consolidated Profit/Loss for the Period 913.8 784.8 16.4% 2,212 1,713 29.1% Consolidated
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50 ri@brasil.isaenergia.com Annex X – Cash Flow – IFRS (R$ thousand) Cash Flow from Operations (R$ thousand) 9M26 9M26 Cash flow from operational activities -4,591,721 -4,457,990 Net earnings 2,244,205 1,759,777 Employee benefit - actuarial deficit 4,060 5,769 Depreciation and amortization 33,072 25,631 Deferred PIS and COFINS 331,728 292,773 Deferred IR and CS 273,584 151,924 Provision for Legal Claims -15,262 -46,226 Residual value of permanent assets written off 29,528 59 Tax benefit - incorporated goodwill 28 27 Income from financial investments -92,156 -104,762 Interest and exchange variations on loans, financing and debentures 1,624,187 1,264,876 Interest and exchange rate variations on assets and liabilities -1,501 -45,101 Result of equity income -359,145 -403,702 Accounts Receivable - Concession Assets -8,355,460 -7,323,530 Financial Instruments -8,349 -3,418 Realization of Concession asset in the acquisition of Subsidiary 12,982 14,461 Transactions with non-controlling shareholders -32,677 -46,548 Bargain Purchase Gain on the Acquisition of an Equity Interest -468,353 0 Loss on Disposal of Equity Interest 187,808 0 Asset Variations 4,065,174 3,923,533 Restricted cash 0 0 Accounts receivable - Concessionaires and Permissionaires 4,706,652 3,909,080 Inventories -45,038 48,404 Accounts Receivable from the State Finance Secretariat -114,173 -141,904 Recoverable taxes and contributions -43,438 125,961 Bonds and linked deposits 1,110 -188 Prepaid expenses -28,590 -6,016 Credit with subsidiaries 0 0 Others -411,349 -11,804 Liabilities Variations -71,011 -82,654 Suppliers -15,058 28,619 Taxes and social charges to be collected 111,521 188,717 Tax payments -173,758 -136,660 Labor obligations 10,223 11,456 Regulatory charges to be collected -29,471 13,784 Provisions -36,396 -5,089 Amounts payable Vivest 0 0 Global Reversion Reserve -1,860 -1,861 Others 63,788 -181,620 Net Cash from Operating Activities -597,558 -617,111 Investments Activites Cash Flow -2,388,505 -502,749 Restricted cash -676 -399 Financial investments -4,051,984 -5,093,394 Redemptions of financial investments 2,476,483 4,115,325 Acquisition of Immobilized -32,901 -10,297 Intangible -22,770 -10,717 Acquisition of Equity Interest -1,415,224 0 Disposal of Equity Interest 462,362 0 Received dividends 196,205 496,733 Cash used in financing activities 2,071,737 -1,075,710 Addition to loans and debentures 6,285,083 2,007,347 Loan payments (principal) -3,769,540 -1,030,172 Loan payments (interest) -926,199 -719,616 Leasing Payments (principal and interest) -18,107 -11,094 Derivative instruments -14,872 13,660 Share Issuance Costs -20,837 0 Proceeds for Capital Increase 1,200,000 0 Dividends and interest on shareholders' equity paid -663,791 -1,335,835 Net variation in Cash and Cash Equivalents -914,326 -2,195,571 Opening Balance of Cash and Cash Equivalents 1,356,062 2,914,747 Closing Balance of Cash and Cash Equivalents 441,736 719,176 Cash and cash equivalents -914,326 -2,195,571 Consolidated