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

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 09.01.2026 / 16:58 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.Notification of Major Holdings1. Details of issuer Name:Adtran Holdings, Inc.Street:901 Explorer BoulevardPostal code:35806City:HuntsvilleUnited StatesLegal Entity Identifier (LEI):549300VV36J86CRRWF772. Reason for notification XAcquisition/disposal of shares with voting rightsXAcquisition/disposal of instruments Change of breakdown of voting rights Other reason:3. Details of person subject to the notification obligation Legal entity: BlackRock, Inc.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: 06 Jan 20266. 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 WpHGNew8.63 %4.98 %13.60 %80188350Previous notification7.48 %5.52 %12.996 %/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)069165960 %8.63 %Total69165968.63 %b.1. Instruments according to Sec. 38 (1) no. 1 WpHG Type of instrumentExpiration or maturity dateExercise or conversion periodVoting rights absoluteVoting rights in %Lent Securities (right to recall)N/AN/A14781831.84 % Total14781831.84 %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 %Contract for DifferenceN/AN/ACash25142183.14 % Total25142183.14 %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)BlackRock, Inc. % % %BlackRock Saturn Subco, LLC % % %BlackRock Finance, Inc. % % %Trident Merger LLC % % %BlackRock Investment Management, LLC % % %- % % %BlackRock, Inc. % % %BlackRock Saturn Subco, LLC % % %BlackRock Finance, Inc. % % %BlackRock Holdco 2, Inc. % % %BlackRock Financial Management, Inc. % % %- % % %BlackRock, Inc. % % %BlackRock Saturn Subco, LLC % % %BlackRock Finance, Inc. % % %BlackRock Holdco 2, Inc. % % %BlackRock Financial Management, Inc. % % %BlackRock Capital Holdings, Inc. % % %BlackRock Advisors, LLC % % %- % % %BlackRock, Inc. % % %BlackRock Saturn Subco, LLC % % %BlackRock Finance, Inc. % % %Trident Merger LLC % % %BlackRock Investment Management, LLC % % %Amethyst Intermediate LLC % % %Aperio Holdings LLC % % %Aperio Group, LLC % % %- % % %BlackRock, Inc. % % %BlackRock Saturn Subco, LLC % % %BlackRock Finance, Inc. % % %BlackRock Holdco 2, Inc. % % %BlackRock Financial Management, Inc. % % %BlackRock International Holdings, Inc. % % %BlackRock Canada Holdings ULC % % %BlackRock Asset Management Canada Limited % % %- % % %BlackRock, Inc. % % %BlackRock Saturn Subco, LLC % % %BlackRock Finance, Inc. % % %BlackRock Holdco 2, Inc. % % %BlackRock Financial Management, Inc. % % %BlackRock Holdco 4, LLC % % %BlackRock Holdco 6, LLC % % %BlackRock Delaware Holdings Inc. % % %BlackRock Fund Advisors % % %- % % %BlackRock, Inc. % % %BlackRock Saturn Subco, LLC % % %BlackRock Finance, Inc. % % %BlackRock Holdco 2, Inc. % % %BlackRock Financial Management, Inc. % % %BlackRock Holdco 4, LLC % % %BlackRock Holdco 6, LLC % % %BlackRock Delaware Holdings Inc. % % %BlackRock Institutional Trust Company, National Association3.28 % % %- % % %BlackRock, Inc. % % %BlackRock Saturn Subco, LLC % % %BlackRock Finance, Inc. % % %BlackRock Holdco 2, Inc. % % %BlackRock Financial Management, Inc. % % %BlackRock International Holdings, Inc. % % %BR Jersey International Holdings L.P. % % %BlackRock Australia Holdco Pty. Ltd. % % %BlackRock Investment Management (Australia) Limited % % %- % % %BlackRock, Inc. % % %BlackRock Saturn Subco, LLC % % %BlackRock Finance, Inc. % % %BlackRock Holdco 2, Inc. % % %BlackRock Financial Management, Inc. % % %BlackRock International Holdings, Inc. % % %BR Jersey International Holdings L.P. % % %BlackRock (Singapore) Holdco Pte. Ltd. % % %BlackRock HK Holdco Limited % % %BlackRock Asset Management North Asia Limited % % %- % % %BlackRock, Inc. % % %BlackRock Saturn Subco, LLC % % %BlackRock Finance, Inc. % % %BlackRock Holdco 2, Inc. % % %BlackRock Financial Management, Inc. % % %BlackRock Holdco 4, LLC % % %BlackRock Holdco 6, LLC % % %BlackRock Delaware Holdings Inc. % % %BlackRock Institutional Trust Company, National Association % % %SAE Liquidity Fund (GenPar), LLC % % %- % % %BlackRock, Inc. % % %BlackRock Saturn Subco, LLC % % %BlackRock Finance, Inc. % % %BlackRock Holdco 2, Inc. % % %BlackRock Financial Management, Inc. % % %BlackRock International Holdings, Inc. % % %BR Jersey International Holdings L.P. % % %BlackRock (Singapore) Holdco Pte. Ltd. % % %BlackRock HK Holdco Limited % % %BlackRock Lux Finco S. a r.l. % % %BlackRock Japan Holdings GK % % %BlackRock Japan Co., Ltd. % % %- % % %BlackRock, Inc. % % %BlackRock Saturn Subco, LLC % % %BlackRock Finance, Inc. % % %BlackRock Holdco 2, Inc. % % %BlackRock Financial Management, Inc. % % %BlackRock International Holdings, Inc. % % %BR Jersey International Holdings L.P. % % %BlackRock Holdco 3, LLC % % %BlackRock Cayman 1 LP % % %BlackRock Cayman West Bay Finco Limited % % %BlackRock Cayman West Bay IV Limited % % %BlackRock Group Limited % % %BlackRock International Limited % % %- % % %BlackRock, Inc. % % %BlackRock Saturn Subco, LLC % % %BlackRock Finance, Inc. % % %BlackRock Holdco 2, Inc. % % %BlackRock Financial Management, Inc. % % %BlackRock International Holdings, Inc. % % %BR Jersey International Holdings L.P. % % %BlackRock Holdco 3, LLC % % %BlackRock Cayman 1 LP % % %BlackRock Cayman West Bay Finco Limited % % %BlackRock Cayman West Bay IV Limited % % %BlackRock Group Limited % % %BlackRock Luxembourg Holdco S.a.r.l. % % %BlackRock Asset Management Ireland Limited % % %- % % %BlackRock, Inc. % % %BlackRock Saturn Subco, LLC % % %BlackRock Finance, Inc. % % %BlackRock Holdco 2, Inc. % % %BlackRock Financial Management, Inc. % % %BlackRock International Holdings, Inc. % % %BR Jersey International Holdings L.P. % % %BlackRock Holdco 3, LLC % % %BlackRock Cayman 1 LP % % %BlackRock Cayman West Bay Finco Limited % % %BlackRock Cayman West Bay IV Limited % % %BlackRock Group Limited % % %BlackRock Finance Europe Limited % % %BlackRock Advisors (UK) Limited % % %- % % %BlackRock, Inc. % % %BlackRock Saturn Subco, LLC % % %BlackRock Finance, Inc. % % %BlackRock Holdco 2, Inc. % % %BlackRock Financial Management, Inc. % % %BlackRock International Holdings, Inc. % % %BR Jersey International Holdings L.P. % % %BlackRock Holdco 3, LLC % % %BlackRock Cayman 1 LP % % %BlackRock Cayman West Bay Finco Limited % % %BlackRock Cayman West Bay IV Limited % % %BlackRock Group Limited % % %BlackRock Luxembourg Holdco S.a.r.l. % % %BlackRock (Luxembourg) S.A. % % %- % % %BlackRock, Inc. % % %BlackRock Saturn Subco, LLC % % %BlackRock Finance, Inc. % % %BlackRock Holdco 2, Inc. % % %BlackRock Financial Management, Inc. % % %BlackRock International Holdings, Inc. % % %BR Jersey International Holdings L.P. % % %BlackRock Holdco 3, LLC % % %BlackRock Cayman 1 LP % % %BlackRock Cayman West Bay Finco Limited % % %BlackRock Cayman West Bay IV Limited % % %BlackRock Group Limited % % %BlackRock Finance Europe Limited % % %BlackRock Investment Management (UK) Limited % % %- % % %BlackRock, Inc. % % %BlackRock Saturn Subco, LLC % % %BlackRock Finance, Inc. % % %BlackRock Holdco 2, Inc. % % %BlackRock Financial Management, Inc. % % %BlackRock International Holdings, Inc. % % %BR Jersey International Holdings L.P. % % %BlackRock Holdco 3, LLC % % %BlackRock Cayman 1 LP % % %BlackRock Cayman West Bay Finco Limited % % %BlackRock Cayman West Bay IV Limited % % %BlackRock Group Limited % % %BlackRock Luxembourg Holdco S.a.r.l. % % %BlackRock UK Holdco Limited % % %BlackRock Asset Management Schweiz AG % % %- % % %BlackRock, Inc. % % %BlackRock Saturn Subco, LLC % % %BlackRock Finance, Inc. % % %BlackRock Holdco 2, Inc. % % %BlackRock Financial Management, Inc. % % %BlackRock International Holdings, Inc. % % %BR Jersey International Holdings L.P. % % %BlackRock Holdco 3, LLC % % %BlackRock Cayman 1 LP % % %BlackRock Cayman West Bay Finco Limited % % %BlackRock Cayman West Bay IV Limited % % %BlackRock Group Limited % % %BlackRock Luxembourg Holdco S.a.r.l. % % %BlackRock Asset Management Ireland Limited % % %BlackRock Solutions Funds ICAV % % %- % % %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: Date09 Jan 2026 09.01.2026 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.com End of NewsEQS News Service2258072 09.01.2026 CET/CEST DisclaimerSaving the news in databases or any forwarding of the news to third parties in a commercial context or for commercial purposes is only permitted with the prior written consent of EQS Group AG.