X0508 4 2023-08-09 0 0000926282 ADTRAN Holdings, Inc. ADTN 0001605860 Theodosopoulos Nikos C/O ADTRAN HOLDINGS, INC. 901 EXPLORER BOULEVARD HUNTSVILLE AL 35806-2807 1 0 0 0 0 Common Stock 2023-08-09 4 M 0 45.973 A 8372.973 D Common Stock 2023-08-09 4 D 0 0.973 D 8372 D Dividend Equivalent Rights 2023-08-09 4 M 0 45.973 0.00 D Common Stock 45.973 99.403 D Dividend Equivalent Rights 2023-09-05 4 A 0 69.021 8.37 A Common Stock 69.021 168.424 D Settlement of dividend equivalent rights (DERs) in connection with the lapse of restrictions on restricted stock awards (RSAs). The DER's represent quarterly cash dividends paid on restricted stock awards, 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 any remaining cash. 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/ Dan Ragsdale, by power of attorney 2023-09-07