GPK: 8-K company filing

8-K 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): June 11, 2026 GRAPHIC PACKAGING HOLDING COMPANY (Exact name of registrant as specified in its charter) Delaware 001-33988 26-0405422 (State or other jurisdiction of incorporation) (Commission File Number) (IRS Employer Identification No.) 1500 Riveredge Parkway Atlanta , Georgia 30328 (Address of principal executive offices) (770) 240-7200 (Registrant’s telephone number, including area code) 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: ☐ 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 Name of Each Exchange on Which Registered Common Stock, $0.01 par value per share GPK New York 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). ☐ 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 acc