Adtran Holdings, Inc.

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

05.08.2026 / 20:21 CET/CEST

Dissemination of a Voting Rights Announcement transmitted by - a service of .

The issuer is solely responsible for the content of this announcement.

Notification of Major Holdings1. Details of issuer
Name:Adtran Holdings, Inc.Street:901 Explorer BoulevardPostal code:35806City:HuntsvilleUnited StatesLegal Entity Identifier (LEI):549300VV36J86CRRWF77
2. Reason for notification
XAcquisition/disposal of shares with voting rights Acquisition/disposal of instruments Change of breakdown of voting rightsXOther reason:voluntary group notification with triggered threshold on subsidiary level
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 3.5. Date on which threshold was crossed or reached:

30 Jul 2026

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 WpHGNew3.87 %3.6 %7.47 %81452688Previous notification3.62 %3.74 %7.36 %/
7. Details on total positions a. Voting rights attached to shares (Sec. 33, 34 WpHG)
ISINAbsoluteIn % Direct (Sec. 33 WpHG)Indirect (Sec. 34 WpHG)Direct (Sec. 33 WpHG)Indirect (Sec. 34 WpHG)US00486H1059031544220 %3.87 %Total31544223.87 %
b.1. Instruments according to Sec. 38 (1) no. 1 WpHG
Type of instrumentExpiration or maturity dateExercise or conversion periodVoting rights absoluteVoting rights in %Right of recall over securities lending agreementsat any timeat any time18740612.3 %  Total18740612.3 %
b.2. Instruments according to Sec. 38 (1) no. 2 WpHG
Type of instrumentExpiration or maturity dateExercise or conversion periodCash or physical settlementVoting rights absoluteVoting rights in %Convertible Bond15.09.2030at any timePhysical10570431.3 %   Total10570431.3 %
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.).XFull 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, LLC % % %Morgan Stanley Capital Services LLC % % %- % % %Morgan Stanley % % %Morgan Stanley Capital Management, LLC % % %Morgan Stanley & Co. LLC % %5.24 %- % % %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 & Co. LLC % %5.24 %Prime Dealer Services Corp. % % %- % % %Morgan Stanley % % %Morgan Stanley Capital Management, LLC % % %Morgan Stanley Bank, N.A. % % %- % % %Morgan Stanley % % %Morgan Stanley Capital Management, LLC % % %Morgan Stanley Smith Barney 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:

The notification was triggered due to an acquisition of client securities over which Morgan Stanley & Co. LLC and Morgan Stanley Smith Barney LLC has a right of use.

Date

05 Aug 2026

05.08.2026 CET/CEST The EQS Distribution Services include Regulatory Announcements, Financial/Corporate News and Press Releases.

Language:EnglishCompany:Adtran Holdings, Inc.901 Explorer Boulevard35806 HuntsvilleUnited StatesInternet:www.adtran.comLEI Code:549300VV36J86CRRWF77
 End of NewsEQS News Service

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