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): May 3, 2024 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction (Commission (IRS Employer of Incorporation) File Number) Identification No .) 901 Explorer Boulevard Huntsville, Alabama 35806-2807 (Address of Pri ...