Adtran Holdings, Inc., US00486H1059

EQS-PVR: Adtran Holdings, Inc.: Release according to Article 40, Section 1 of the WpHG [the German Securities Trading Act] with the objective of Europe-wide distribution

Notification of Major Holdings

1. Details of issuer Name: Adtran Holdings, Inc. Street: 901 Explorer Boulevard Postal code: 35806 City: HuntsvilleUnited States Legal Entity Identifier (LEI): 549300VV36J86CRRWF77 2. Reason for notification X Acquisition/disposal of shares with voting rights ? Acquisition/disposal of instruments ? Change of breakdown of voting rights ? Other reason: 3. Details of person subject to the notification obligation Legal entity: Morgan StanleyCity of registered office, country: Wilmington, Delaware, United States of America (USA) 4. Names of shareholder(s) holding directly 3% or more voting rights, if different from 3.Morgan Stanley & Co. LLC 5. Date on which threshold was crossed or reached: 22 May 2023 6. Total positions ? % of voting rights attached to shares (total of 7.a.) % of voting rights through instruments (total of 7.b.1 + 7.b.2) Total of both in % (7.a. + 7.b.) Total number of voting rights pursuant to Sec. 41 WpHG New 3.58 % 1.76 % 5.34 % 78655333 Previous notification 0.89 % 2.54 % 3.43 % / 7. Details on total positions a. Voting rights attached to shares (Sec. 33, 34 WpHG) ISIN Absolute In % ? Direct (Sec. 33 WpHG) Indirect (Sec. 34 WpHG) Direct (Sec. 33 WpHG) Indirect (Sec. 34 WpHG) US00486H1059 0 2817773 0 % 3.58 % Total 2817773 3.58 % b.1. Instruments according to Sec. 38 (1) no. 1 WpHG Type of instrument Expiration or maturity date Exercise or conversion period Voting rights absolute Voting rights in % Equity Call Option From 16.06.2023 to 15.12.2023 at any time 600 0 % Right of recall over securities lending agreements at any time at any time 1383279 1.76 % ? ? Total 1383879 1.76 % b.2. Instruments according to Sec. 38 (1) no. 2 WpHG Type of instrument Expiration or maturity date Exercise or conversion period Cash or physical settlement Voting rights absolute Voting rights in % Equity Put Option From 18.08.2023 to 15.09.2023 at any time Physical 1300 0 % Retail Structured Product 09.09.2072 at any time Cash 100 0 % ? ? ? Total 1400 0.001779917453 % 8. Information in relation to the person subject to the notification obligation? Person subject to the notification obligation is not controlled nor does it control any other undertaking(s) that directly or indirectly hold(s) an interest in the (underlying) issuer (1.). X Full chain of controlled undertakings starting with the ultimate controlling natural person or legal entity: Name % of voting rights (if at least 3% or more) % of voting rights through instruments (if at least 5% or more) Total of both (if at least 5% or more) Morgan Stanley % % % Morgan Stanley Capital Management, LLC % % % Morgan Stanley Domestic Holdings, Inc. % % % Morgan Stanley & Co. LLC 3.42 % % % - % % % Morgan Stanley % % % Morgan Stanley International Holdings Inc. % % % Morgan Stanley International Limited % % % Morgan Stanley Investments (UK) % % % Morgan Stanley & Co. International plc % % % - % % % Morgan Stanley % % % Morgan Stanley Capital Management, LLC % % % Morgan Stanley Domestic Holdings, Inc. % % % Morgan Stanley & Co. LLC 3.42 % % % Prime Dealer Services Corp. % % % - % % % Morgan Stanley % % % Morgan Stanley Capital Management, LLC % % % Morgan Stanley Domestic Holdings, Inc. % % % Morgan Stanley Smith Barney LLC % % % - % % % Morgan Stanley % % % Morgan Stanley Capital Management, LLC % % % Morgan Stanley Domestic Holdings, Inc. % % % ETCM Holdings, LLC % % % E*TRADE Securities LLC % % % 9. In case of proxy voting according to Sec. 34 para. 3 WpHG (only in case of attribution of voting rights in accordance with Sec. 34 para. 1 sent. 1 No. 6 WpHG) Date of general meeting: Holding total positions after general meeting (6.) after annual general meeting:Proportion of voting rights Proportion of instruments Total of both % % % 10. Other explanatory remarks:? Date26 May 2023

26.05.2023 CET/CEST The EQS Distribution Services include Regulatory Announcements, Financial/Corporate News and Press Releases.Archive at www.eqs-news.com

Language: English Company: Adtran Holdings, Inc. 901 Explorer Boulevard 35806 Huntsville

United States Internet: www.adtran.com ? End of News EQS News Service

1643495??26.05.2023?CET/CEST