Ad-hoc notification pursuant to Article 17 of Regulation (EU) No. 596/2014

ADTRAN Holdings, Inc.: Restatement of results attributable to minority shareholders of Adtran Networks SE and of net loss and loss per common share attributable to ADTRAN Holdings, Inc. for Q1 2023 through Q3 2023

Huntsville, Alabama (United States of America). February 20, 2024 (CT)

The Audit Committee of the Board of Directors (“Audit Committee”) of ADTRAN Holdings, Inc. (“Company”) concluded today, that the presentation of the results attributable to the minority shareholders of the Company’s majority-owned subsidiary, Adtran Networks SE (“Adtran Networks”), of the net loss attributable to the Company and, as a consequence, of the loss per common share attributable to the Company was incorrect in (i) the Company’s unaudited condensed consolidated financial statements as of and for the quarter ended March 31, 2023, (ii) the Company’s unaudited condensed consolidated financial statements as of and for the quarter and six months ended June 30, 2023, and (iii) the Company’s unaudited condensed consolidated financial statements as of and for the quarter and nine months ended September 30, 2023, respectively.

The misstatements are solely related and limited to the financial statement presentation below the reported consolidated net loss line item and specific to the bifurcation of net income and loss per share on the condensed consolidated statements of loss to the Company and the non-controlling interest. The error does not have any impact on, or result in any change to, the reported amounts through consolidated net loss on the condensed consolidated statements of loss, the Company’s condensed consolidated balance sheets or condensed consolidated statements of cash flows.

The misstatements occurred following the effectiveness of the Domination Profit and Loss Transfer Agreement (“DPLTA”) between the Company and Adtran Networks upon registration of the DPLTA with the commercial register on January 16, 2023.

Pursuant to the DPLTA, the minority shareholders of Adtran Networks are guaranteed recurring cash compensation commencing with respect to the 2023 fiscal year. The Company incorrectly presented the guaranteed cash compensation attributable to the non-controlling interest as a loss rather than income attributable to the non-controlling interest. This error resulted in an understatement of net income attributable to the non-controlling interest, and an understatement of net loss attributable to the Company and loss per common share attributable to ADTRAN Holdings, Inc., both basic and diluted.

The following table reflects the impact of the corrections to the specific line items presented in the Company’s previously reported condensed consolidated statements of loss for the three months ended March 31, 2023, the three and six months ended June 30, 2023, and the three and nine months ended September 30, 2023:

The errors will be corrected in restated financial statements in amendments to the Company’s quarterly reports on Form 10-Q for each of the fiscal quarters ended March 31, 2023, June 30, 2023, and September 30, 2023. The Company intends to file such amendments prior to the filing of the Company’s annual report on Form 10-K for the fiscal year ended December 31, 2023.

Cautionary Note Regarding Forward-Looking Statements

Statements contained in this ad hoc notification contain forward-looking statements that are based on our management’s beliefs and assumptions and on information currently available to our management. Forward-looking statements include, among other things, statements regarding the Company’s intent to restate its prior consolidated financial statements for the first three quarters of 2023, the estimated impact of adjustments to the financial statements for the first three quarters of 2023, the timing for filing the amendments to the quarterly reports on Form 10-Q for the first three quarters of 2023, and related matters. Forward-looking statements include statements that are not historical facts and can be identified by terms such as “anticipate,” “believe,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “potential,” “predict,” “project,” “seek,” “should,” “will,” “would” or similar expressions and the negatives of those terms. Our actual results and the timing of events could materially differ from those anticipated in such forward-looking statements as a result of certain risks and uncertainties including those described in more detail in the Company’s most recent annual report on Form 10-K, as amended, and quarterly report on Form 10-Q and other documents on file with the SEC, as well as the risk of the possibility of further material delays in the Company’s financial reporting. The Company disclaims and does not undertake any obligation to update or revise any forward-looking statement in this filing, except as required by applicable law or regulation.

Published by

Adtran Holdings, Inc.

www.adtran.com

For media

Gareth Spence

+44 1904 699 358

public.relations@adtran.com

Notifying person and contact for investors

Steven Williams

+49 89 890 665 918

investor.relations@adtran.com