Results of Operations

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934 Date of Report (date of earliest event reported): April 30, 2026 International Paper Company (Exact name of registrant as specified in its charter) Commission file number 1-3157   New York 13-0872805 (State or other jurisdiction of incorporation) (I.R.S. Employer Identification No.) 6400 Poplar Avenue , Memphis , Tennessee 38197 (Address of Principal Executive Offices) (Zip Code) Registrant's telephone number, including area code: ( 901 ) 419-9000 Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below): ☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) Securities registered pursuant to Section 12(b) of the Act: Title of each class Trading Symbol(s) Name of each exchange on which registered Common Stock, $1 per share par value IP New York Stock Exchange Common Stock, $1 per share par value IPC London Stock Exchange Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). Emerging growth company ☐ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐ EXPLANATORY NOTE The information in this Current Report on Form 8-K (the "Report"), including the exhibit, is furnished pursuant to Item 2.02 and General Instruction B.2 thereunder. Such information shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended. SECTION 2. FINANCIAL INFORMATION. Item 2.02.   Results of Operations and Financial Condition. On April 30, 2026, International Paper Company (the “Company”) issued a press release announcing its preliminary, unaudited financial results for the fiscal quarter ended March 31, 2026. The Company will host a webcast and conference call today to discuss results for the fiscal quarter ended March 31, 2026. During the call, the Company will also provide an update on the separation of our Europe, Middle East and Africa packaging business and adjust its 2026 full year target. Attached as Exhibit 99.1 and incorporated herein by reference is a copy of the press release. SECTION 9. FINANCIAL STATEMENTS AND EXHIBITS. Item 9.01.   Financial Statements and Exhibits. (d) Exhibits. The following exhibit is being furnished as part of this Report. Exhibit Number    Description 99.1    Press Release of International Paper Company dated April 30, 2026 EXHIBIT INDEX   Exhibit Number   Description 99.1   Press Release of International Paper dated April 30, 2026. 101 Cover Page Interactive Data File - the cover page XBRL tags are embedded within the Inline XBRL document. 104 The cover page from this Current Report on Form 8-K, formatted as Inline XBRL. SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.   International Paper Company Date: April 30, 2026 By: /s/ Holly G. Goughnour Name: Holly G. Goughnour Title: Vice President - Chief Accounting Officer