Item 4.01 Changes in Registrant's Certifying Accountant. On July 21, 2026, the Financial Audit Committee (the “Audit Committee”) of the Board of Directors of The AES Corporation (the “Company”) dismissed Ernst & Young LLP (“EY”) as the Company’s independent registered public accounting firm, due to the fact that EY will no longer be considered independent with respect to the Company under the rules of the Securities and Exchange Commission (the “SEC”) after the closing of the announced Agreement and Plan of Merger (the “Merger Agreement”), by and among the Company, Horizon Parent, L.P., a Delaware limited partnership (“Parent”), and Horizon Merger Sub, Inc., a Delaware corporation and wholly owned subsidiary of Parent (“Merger Sub”). Pursuant to the Merger Agreement, on the terms and subject to the conditions set forth therein, Merger Sub will merge with and into the Company (the “Merger”), with the Company continuing as the surviving corporation in the Merger. Parent is jointly controlled by investment vehicles affiliated with one or more funds, accounts or other entities managed or advised by Global Infrastructure Management, LLC and the EQT Infrastructure VI fund. The dismissal is effective upon the filing of the Company’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2026. The audit reports of EY on the Company’s consolidated financial statements as of and for the fiscal years ended December 31, 2024 and 2025 did not contain an adverse opinion or a disclaimer of opinion, nor were such reports qualified or modified as to uncertainty, audit scope or accounting principles. EY’s report on the Company’s internal control over financial reporting as of December 31, 2024 contained an adverse opinion. Specifically, EY’s report stated that the Company had not maintained effective internal control over financial reporting as of December 31, 2024 due to the effect of a material weakness identified by management in controls related to the disposition process of AES Brasil, as reported by the Company in “Part II, Item 9A. Controls and Procedures” of its Annual Report on Form 10-K for the fiscal year ended December 31, 2024, filed with the SEC on March 11, 2025. This material weakness was discussed by the Audit Committee and EY. During the fiscal years ended December 31, 2024 and 2025, and the subsequent interim period through the date of this Current Report on Form 8- K (this “Current Report”), there were no (i) disagreements (within the meaning of Item 304(a)(1)(iv) of Regulation S-K and the related instructions under the Securities Exchange Act of 1934, as amended (the “Exchange Act”)) between the Company and EY on any matter of accounting principles or practices, financial statement disclosure or auditing scope or procedure, which, if not resolved to the satisfaction of EY, would have caused EY to make reference to the subject matter of the disagreement in connection with its report on the consolidated financial statements of the Company for the applicable year, or (ii) reportable events (within the meaning of Item 304(a)(1)(v) of Regulation S-K and the related instructions under the Exchange Act), other than the material weakness described above. The Company has provided EY with a copy of the disclosures in this Current Report and has requested that EY provide the Company with a letter addressed to the SEC stating whether EY agrees with the statements made by the Company herein. A copy of EY’s letter, dated July 27, 2026, is filed as Exhibit 16.1 to this Current Report. Following consideration of multiple accounting firms, on July 21, 2026, the Audit Committee engaged KPMG LLP (“KPMG”) as the independent registered public accounting firm for the Company for the fiscal year ending December 31, 2026, effective as of EY’s dismissal upon the filing of the Company’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2026. As part of the request for proposal process by which KPMG was selected, KPMG and the Company identified that, during the year ending December 31, 2026 (the “Audit Period”), various member firms within the KPMG International network (“KPMG Member Firms”) provided tax advisory support, payroll processing, employment legal advice, and financial model review services to certain subsidiaries of the Company. Each of these services contain one or more components of work performed during the Audit Period that render them to be impermissible services (“Impermissible Services”) pursuant to SEC Regulation S-X Rule 2-01 and therefore impact KPMG’s independence with respect to the Company. Prior to the appointment of KPMG as the independent registered public accounting firm for the Company, all Impermissible Services have either been completed or terminated. The Impermissible Services were strictly advisory or clerical in nature, and management of the Company retained sole decision-making authority and responsibility for all underlying data and assumptions. Additionally, these services were limited to foreign affiliates, the subject matters to which the services relate are not expected to be in-scope for the consolidated group audit of the Company, and the fees associated with the Impermissible Services are immaterial to each of the Company and KPMG. KPMG considered whether the matters noted above impacted its objectivity and ability to exercise impartial judgment with regard to its engagement as the Company’s independent registered public accounting firm and has concluded that KPMG’s objectivity and ability to exercise impartial judgment has not been impaired. After taking into consideration the facts and circumstances of the above matters and KPMG’s determination, the Company’s Audit Committee also concluded that KPMG’s objectivity and ability to exercise impartial judgment has not been impaired. During the fiscal years ended December 31, 2024 and 2025, and the subsequent interim period through the date of this Current Report, neither the Company, nor anyone on the Company’s behalf, consulted with KPMG regarding either (1) the application of accounting principles to a specified transaction, either completed or proposed, or the type of audit opinion that might be rendered on the Company’s consolidated financial statements, and no written report or oral advice was provided by KPMG to the Company that KPMG concluded was an important factor considered by the Company in reaching a decision as to the accounting, auditing or financial reporting issue; or (2) any matter that was the subject of either a disagreement (within the meaning of Item 304(a)(1)(iv) of Regulation S-K and the related instructions under the Exchange Act) or a reportable event (within the meaning of Item 304(a)(1)(v) of Regulation S-K and the related instructions under the Exchange Act). Item 9.01 Financial Statements and Exhibits. (d) Exhibits Exhibit No. Description 16.1 Letter to the Securities and Exchange Commission from Ernst & Young LLP, dated Ju ly 2 7 , 2026 101 Inline XBRL Document Set for the Cover Page from this Current Report on Form 8-K, formatted as Inline XBRL 104 Cover Page Interactive Data File (embedded within the Inline XBRL document) SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf of the undersigned hereunto duly authorized. THE AES CORPORATION Date: July 27, 2026 By: /s/ Stephen Coughlin Name: Stephen Coughlin Title: Executive Vice President and Chief Financial Officer