UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from _______ to _______ Commission File Number: 001-41446 ADTRAN Holdings, Inc. (Exact Name of Registrant as Specified in its Charter) Delaware 87-2164282 (State or other jurisdiction of incorporation or organization) (I.R.S. Employer Identification No.) (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 1 ...