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

EQS Voting Rights Announcement: 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 20.04.2026 / 20:25 CET/CEST Dissemination of a Voting Rights Announcement transmitted by EQS News - a service of EQS Group. The issuer is solely responsible for the content of this announcement.

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Notification of Major Holdings

1. Details of issuer

Name:	Adtran Holdings, Inc.
Street:	901 Explorer Boulevard
Postal code:	35806
City:	Huntsville United States
Legal Entity Identifier (LEI):	549300VV36J86CRRWF77

2. Reason for notification

	Acquisition/disposal of shares with voting rights
X	Acquisition/disposal of instruments
	Change of breakdown of voting rights
	Other reason:

3. Details of person subject to the notification obligation

Legal entity: Morgan Stanley City 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:

14 Apr 2026