EQS — PVR: ADTRAN Holding, 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 Holding, Inc.: Release according to Article 40, Section 1 of the WpHG [the German Securities Trading Act] with the objective of Europe-wide distribution 18.09.2026 / 18:57 CET/CEST Dissemination of a Voting Rights Announcement transmitted by 1 EQS News — a service of 2 EQS Group. The issuer is solely responsible for the content of this announcement. ══════════════════════════════════════════════════════════════════════════ 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/di