X0306 4 2022-07-08 0 0000926282 ADTRAN Holdings, Inc. ADTN 0001191219 STANTON THOMAS R C/O ADTRAN HOLDINGS, INC. 901 EXPLORER BLVD. HUNTSVILLE AL 35806 1 1 0 0 Chairman, CEO and President Common Stock 2022-07-08 4 A 0 637792.09 A 637792.09 D Incentive Stock Option (Right to Buy) 15.33 2022-07-08 4 A 0 6523 A 2025-11-14 Common Stock 6523 6523 D Non-Qualified Stock Option (Right to Buy) 15.33 2022-07-08 4 A 0 87684 A 2025-11-14 Common Stock 87864 87864 D Incentive Stock Option (Right to Buy) 18.97 2022-07-08 4 A 0 5271 A 2024-11-15 Common Stock 5271 5271 D Non-Qualified Stock Option (Right to Buy) 18.97 2022-07-08 4 A 0 88936 A 2024-11-15 Common Stock 88936 88936 D Incentive Stock Option (Right to Buy) 23.64 2022-07-08 4 A 0 4230 A 2023-11-02 Common Stock 4230 4230 D Non-Qualified Stock Option (Right to Buy) 23.64 2022-07-08 4 A 0 71136 A 2023-11-02 Common Stock 71136 71136 D Incentive Stock Option (Right to Buy) 16.97 2022-07-08 4 A 0 5893 A 2022-11-06 Common Stock 5893 5893 D Non-Qualified Stock Option (Right to Buy) 16.97 2022-07-08 4 A 0 69473 A 2022-11-06 Common Stock 69473 69473 D Phantom Stock 2022-07-08 4 A 0 158297.672 A Common Stock 158297.672 158297.672 D Pursuant to that certain Business Combination Agreement, dated August 30, 2021, by and among ADTRAN, Inc.; ADVA Optical Networking SE; the Issuer (f/k/a Acorn HoldCo, Inc.); and Acorn MergeCo, Inc., ADTRAN, Inc. became a wholly owned subsidiary of the Issuer on July 8, 2022 (the "Effective Time"). At the Effective Time, (a) each share of ADTRAN, Inc.'s common stock converted, on a one-for-one basis, into a share of the Issuer's common stock; (b) each RSU measured in shares of ADTRAN, Inc.'s common stock, whether vested or unvested, converted, on a one-for-one basis, into an RSU measured in shares of the Issuer's common stock on the same terms and conditions as were applicable to the corresponding RSU immediately prior to the Effective Time; (Continued from footnote 1) (c) each option to purchase ADTRAN, Inc.'s common stock converted, on a one-for-one basis, into an option to purchase shares of the Issuer's 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 ADTRAN, Inc. (representing the economic equivalent of one share of ADTRAN, Inc.'s common stock) converted, on a one-for-one basis, into a share of phantom stock of the Issuer on the same terms and conditions as were applicable to the corresponding phantom stock immediately prior to the Effective Time. Includes 444,193 time-based restricted stock units ("RSUs") that settle upon vesting in shares of the Issuer's common stock, 111,959 of which were converted from RSUs measured in ADTRAN, Inc.'s common stock owned by the reporting person prior to the Effective Time (as defined below), and 332,234 of which were acquired in connection with the conversion of a target number of unearned performance stock units ("PSUs") measured in shares of ADTRAN, Inc.'s common stock owned by the reporting person prior to the Effective Time (as defined below). The options granted to the reporting person vested in four annual installments beginning on the anniversary of the date of grant and were fully vested prior to the Effective Time. Represents shares of phantom stock of the Issuer that have been acquired through the automatic reinvestment of dividends paid on the Issuer's common stock, which phantom shares become payable in cash six months after the reporting person's separation of service with the Issuer. /s/ Michael Foliano, by power of attorney 2022-07-11