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

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

X	Acquisition/disposal of shares with voting rights
	Acquisition/disposal of instruments
	Change of breakdown of voting rights
X	Other reason: voluntary group notification with triggered threshold on subsidiary level

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.

Morgan Stanley & Co. LLC

5. Date on which threshold was crossed or reached:

28 Aug 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 WpHG
New	3.67 %	3.29 %	6.96 %	81481407
Previous notification	3.46 %	3.31 %	6.77 %	/

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	2990176	0 %	3.67 %
Total	2990176		3.67 %

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 %
Right of recall over securities lending agreements	at any time	at any time	1625225	1.99 %
		Total	1625225	1.99 %

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 %
Convertible Bond	15.09.2030	at any time	Physical	1057043	1.3 %
			Total	1057043	1.3 %

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.).
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, LLC	%	%	%
Morgan Stanley Capital Services LLC	%	%	%
-	%	%	%
Morgan Stanley	%	%	%
Morgan Stanley Capital Management, LLC	%	%	%
Morgan Stanley & Co. LLC	3.02 %	%	5.5 %
-	%	%	%
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	3.02 %	%	5.5 %
Prime Dealer Services Corp.	%	%	%
-	%	%	%
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 mainly due to an acquisition of shares with voting rights, in addition to an acquisition of client securities over which Morgan Stanley & Co. LLC has a right of use.

Date

02 Sep 2026