X0407 4 2023-03-21 0 0000926282 ADTRAN Holdings, Inc. ADTN 0001264261 Walker Kathryn A C/O ADTRAN HOLDINGS, INC. 901 EXPLORER BOULEVARD HUNTSVILLE AL 35806-2807 1 0 0 0 0 Dividend Equivalent Rights 2023-03-21 4 A 0 36.197 15.96 A Common Stock 36.197 36.197 D Represents quarterly cash dividends paid on restricted stock awards (RSAs), which are credited to a bookkeeping account and hypothetically invested in shares of common stock until the underlying RSAs vest. Upon vesting, the Company pays the Reporting Person the accumulated value of the bookkeeping account in the form of whole shares of common stock, plus cash for any fractional shares. /s/ Michael Foliano, by power of attorney 2023-03-23