[8-K] ADTRAN Holdings, Inc. Reports Material Event

Rhea-AI Filing Summary

ADTRAN Holdings, Inc. furnished an update that it has released certain preliminary financial results for its fiscal quarter and full year ended December 31, 2025. These figures were shared through a press release and an accompanying ad hoc announcement.

Because ADTRAN is also listed on the Frankfurt Stock Exchange, it must follow European Market Abuse Regulation rules, which require real-time disclosure when expected results materially deviate from previously announced guidance or analyst consensus. To meet these obligations, ADTRAN published an ad hoc announcement in Germany covering preliminary results for the quarter ended December 31, 2025, and attached both the press release and the ad hoc notice as exhibits to this report.

Insights

Cross‑listed equities analyst

ADTRAN flags a material deviation from prior expectations but gives no numbers yet.

ADTRAN states that, as a Frankfurt‑listed issuer, it must disclose when management’s expected results materially deviate from previously announced guidance or analyst consensus under the EU Market Abuse Regulation. It then notes that it has published an ad hoc announcement in Germany with preliminary results for the quarter ended December 31, 2025, and furnished the same information in this report.

The explicit reference to a material deviation signals that upcoming results differ meaningfully from what the market had been led to expect, although the direction and size are not detailed here. The actual impact for investors will depend on the figures and commentary contained in the attached press release and ad hoc announcement, which are incorporated by reference but not summarized in this text.

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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): January 21, 2026

ADTRAN Holdings, Inc.

(Exact name of Registrant as Specified in Its Charter)

Delaware			001-41446	87-2164282
(State or Other Jurisdiction of Incorporation)			(Commission File Number)	(IRS Employer Identification No.)
901 Explorer Boulevard
Huntsville, Alabama				35806-2807
(Address of Principal Executive Offices)				(Zip Code)

Registrant’s Telephone Number, Including Area Code: (256) 963-8000

Not Applicable

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class		Trading Symbol(s)		Name of each exchange on which registered
Common Stock, Par Value $0.01 per share		ADTN		Nasdaq Global Select Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 2.02 Results of Operations and Financial Condition.

On January 21, 2026, ADTRAN Holdings, Inc. (“ADTRAN”) announced certain preliminary financial results for the fiscal quarter and year ended December 31, 2025.

A copy of ADTRAN’s press release announcing certain preliminary financial results is attached as Exhibit 99.1 hereto and incorporated by reference in this Item 2.02.

Item 7.01 Regulation FD Disclosure.

As a company listed on the Frankfurt Stock Exchange, ADTRAN is subject to German and European securities laws. Article 17 of the Market Abuse Regulation (EU) No. 596/2014 (the "MAR") of the European Parliament and of the Council of 16 April 2014 mandates that listed issuers such as ADTRAN provide real time disclosure in certain circumstances, including where management’s expected results materially deviate from previously announced guidance or analyst consensus. On January 21, 2026, ADTRAN published an ad hoc announcement in Germany disclosing certain preliminary financial results for the fiscal quarter ended December 31, 2025 in accordance with the MAR.

A copy of ADTRAN’s ad hoc announcement is attached as Exhibit 99.2 hereto and incorporated by reference in this Item 7.01.

The information included in, or incorporated into, Items 2.02 and 7.01 of this Current Report on Form 8-K is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

Item 9.01 Financial Statements and Exhibits.

Exhibit Number	Description
99.1	Press Release dated January 21, 2026
99.2	Ad Hoc Notification dated January 21, 2026 (English translation)
104	Cover Page Interactive Data File – the cover page iXBRL tags are embedded within the Inline XBRL document

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

			ADTRAN Holdings, Inc.
Date:	January 21, 2026	By:	/s/ Timothy Santo
			Timothy Santo Senior Vice President of Finance and Chief Financial Officer

FAQ

What did ADTRAN (ADTN) disclose in this 8-K?

ADTRAN furnished an update that it has released certain preliminary financial results for the fiscal quarter and full year ended December 31, 2025, via a press release and an ad hoc announcement.

Which periods do ADTRAN’s preliminary results cover?

The preliminary financial results relate to ADTRAN’s fiscal quarter and fiscal year ended December 31, 2025, with the ad hoc announcement specifically addressing the quarter ended on that date.

Why is ADTRAN subject to European Market Abuse Regulation requirements?

ADTRAN is listed on the Frankfurt Stock Exchange, so it must comply with EU Market Abuse Regulation rules, including real-time disclosure when expected results materially deviate from previously announced guidance or analyst consensus.

How did ADTRAN comply with the EU Market Abuse Regulation in this case?

On January 21, 2026, ADTRAN published an ad hoc announcement in Germany disclosing certain preliminary financial results for the quarter ended December 31, 2025, and furnished that announcement as an exhibit.

Where can investors find the detailed preliminary financial results for ADTRAN?

The detailed preliminary results are contained in ADTRAN’s press release dated January 21, 2026 (Exhibit 99.1) and the ad hoc notification of the same date (Exhibit 99.2), which are attached to this report.

Are ADTRAN’s preliminary results considered filed financial information?

No. The information in Items 2.02 and 7.01, including the attached exhibits, is being furnished and is expressly stated as not deemed filed for purposes of Section 18 of the Securities Exchange Act of 1934.