X0306 4 2022-07-08 1 0000926282 ADTRAN INC ADTN 0001300513 Foliano Michael C/O ADTRAN 901 EXPLORER BLVD. HUNTSVILLE AL 35806 0 1 0 0 Chief Financial Officer Common Stock 2022-07-08 4 D 0 52912.366 D 0 D Common Stock 2022-07-08 4 D 0 247.958 D 0 I 401(k) Plan Incentive Stock Option (Right to Buy) 15.33 2022-07-08 4 D 0 5644 D Common Stock 5644 0 D Non-Qualified Stock Option (Right to Buy) 15.33 2022-07-08 4 D 0 16934 D Common Stock 16934 0 D Incentive Stock Option (Right to Buy) 18.97 2022-07-08 4 D 0 5271 D Common Stock 5271 0 D Non-Qualified Stock Option (Right to Buy) 18.97 2022-07-08 4 D 0 17307 D Common Stock 17307 0 D Incentive Stock Option (Right to Buy) 23.64 2022-07-08 4 D 0 5219 D Common Stock 5219 0 D Non-Qualified Stock Option (Right to Buy) 23.64 2022-07-08 4 D 0 12843 D Common Stock 12843 0 D Incentive Stock Option (Right to Buy) 16.97 2022-07-08 4 D 0 4515 D Common Stock 4515 0 D Non-Qualified Stock Option (Right to Buy) 16.97 2022-07-08 4 D 0 13547 D Common Stock 13547 0 D Phantom Stock 2022-07-08 4 D 0 21112.16 D Common Stock 21112.16 0 D Includes 26,524 time-based restricted stock units ("RSUs") that settle upon vesting in shares of the Issuer's common stock. Pursuant to that certain Business Combination Agreement, dated August 30, 2021, by and among the Issuer, ADVA Optical Networking SE, Acorn HoldCo, Inc. (now named ADTRAN Holdings, Inc. ("Holdings")), and Acorn MergeCo, Inc., the Issuer became a wholly owned subsidiary of Holdings on July 8, 2022 (the "Effective Time"). At the Effective Time, (a) each share of the Issuer's common stock converted, on a one-for-one basis, into a share of Holdings' common stock; (b) each RSU measured in shares of the Issuer's common stock, whether vested or unvested, converted, on a one-for-one basis, into an RSU measured in shares of Holdings' common stock on the same terms and conditions as were applicable to the corresponding RSU immediately prior to the Effective Time; (Continued from footnote 2) (c) each option to purchase the Issuer's common stock converted, on a one-for-one basis, into an option to purchase shares of Holdings' common stock on the same terms and conditions as were applicable to the corresponding option immediately prior to the Effective Time; and (d) each share of phantom stock of the Issuer (representing the economic equivalent of one share of the Issuer's common stock) converted, on a one-for-one basis, into a share of phantom stock of Holdings on the same terms and conditions as were applicable to the corresponding phantom stock immediately prior to the Effective Time. The reporting person's status as an officer of the Issuer terminated as of the Effective Time. /s/ Michael Foliano 2022-07-08