X0206 3 2022-07-15 0 0000926282 ADTRAN Holdings, Inc. ADTN 0001605860 Theodosopoulos Nikos C/O ADTRAN HOLDINGS, INC. 901 EXPLORER BLVD. HUNTSVILLE AL 35806 1 0 0 0 No securities are beneficially owned 0 D Immediately following the Closing of the Exchange Offer (as defined in that certain Business Combination Agreement dated as of August 30, 2021, by and among ADTRAN, Inc., ADVA Optical Networking SE, the Issuer (f/k/a Acorn HoldCo, Inc.), and Acorn MergeCo, Inc.), the reporting person became a member of the Board of Directors of the Issuer. /s/ Michael Foliano, by power of attorney 2022-07-18