ADTN / ADTRAN Holdings, Inc. - Zgłoszenia SEC, Raport roczny, o pełnomocnictwie

ADTRAN Holdings, Inc.
US ˙ NasdaqGS ˙ US00486H1059

Podstawowe statystyki
LEI 549300XWTHXJVGKWU616
CIK 926282
SEC Filings
All companies that sell securities in the United States must register with the Securities and Exchange Commission (SEC) and file reports on a regular basis. These reports include company annual reports (10K, 10Q), news updates (8K), investor presentations (found in 8Ks), insider trades (form 4), ownership reports (13D, and 13G), and reports related to the specific securities sold, such as registration statements and prospectus. This page shows recent SEC filings related to ADTRAN Holdings, Inc.
SEC Filings (Chronological Order)
Na tej stronie znajduje się pełna, chronologiczna lista zgłoszeń SEC, z wyłączeniem zgłoszeń własności, które udostępniamy gdzie indziej.
May 18, 2026 8-K

FORM 8-K Proposal 2 - Amendment to Amended and Restated Certificate of Incorporation to Limit the Liability of Certain Officers as Permitted by Delaware Law and to Make Certain Other Changes to Section 7.1 Thereof Item 9.01 Financial Statements and E

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): May 13, 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

May 18, 2026 EX-3.1

CERTIFICATE OF AMENDMENT TO THE AMENDED AND RESTATED CERTIFICATE OF INCORPORATION ADTRAN HOLDINGS, INC.

Exhibit 3.1 CERTIFICATE OF AMENDMENT TO THE AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF ADTRAN HOLDINGS, INC. ADTRAN Holdings, Inc. (the “Corporation”), a corporation organized and existing under and by virtue of the General Corporation Law of the State of Delaware (the “DGCL”) does hereby certify: FIRST: The name of the Corporation is ADTRAN Holdings, Inc. SECOND: The Board of Directors

May 12, 2026 EX-1.01

Conflict Minerals Report of ADTRAN Holdings, Inc.

Exhibit 3.01 Conflict Minerals Report of ADTRAN Holdings, Inc. Company Overview ADTRAN Holdings, Inc. (NASDAQ:ADTN) (“ADTRAN” or the “Company”) is a leading global provider of networking and communications platforms, software, systems and services focused on the metro optical transport, data center interconnect, and broadband access market, serving a diverse domestic and international customer bas

May 12, 2026 SD

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM SD Specialized Disclosure Report ADTRAN Holdings, Inc. (Exact name of Registrant as specified in its charter)

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM SD Specialized Disclosure Report ADTRAN Holdings, Inc. (Exact name of Registrant as specified in its charter) Delaware (State or other jurisdiction of incorporation or organization) 001-41446 (Commission File Number) 87-2164282 (I.R.S. Employer Identification No.) 901 Explorer Boulevard, Huntsville, Alabama (Address of pr

May 5, 2026 EX-99.2

Adtran Holdings (Nasdaq: ADTN) Investor presentation May 5, 2026

Adtran Holdings (Nasdaq: ADTN) Investor presentation May 5, 2026 Cautionary note regarding forward-looking statements Statements and graphics contained in this investor presentation which are not historical facts, such as those relating to market trends, future demand driver growth (including with respect to future fiber expansion, service provider fiber networking demand, future high-risk vendor displacement, data center expansion, and future customer opportunities), the impact of AI on customer network operations, future AI uses, and ADTRAN Holdings’ strategy, outlook and financial guidance, are forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995.

May 5, 2026 EX-10.5

ADTRAN HOLDINGS, INC.

Exhibit 10.5 * CERTAIN IDENTIFIED INFORMATION HAS BEEN EXCLUDED FROM THIS EXHIBIT BECAUSE IT IS NOT MATERIAL AND IS THE TYPE OF INFORMATION THE REGISTRANT CUSTOMARILY AND ACTUALLY TREATS AS PRIVATE AND CONFIDENTIAL. REDACTED INFORMATION IS INDICATED BY [***]. ADTRAN HOLDINGS, INC. T. STANTON RESTRICTED STOCK UNIT AGREEMENT This Restricted Stock Unit Agreement (this “Agreement”) sets forth the spec

May 5, 2026 8-K

FORM 8-K Item 2.02 Results of Operations and Financial Condition.

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): May 04, 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

May 5, 2026 EX-10.4

ADTRAN HOLDINGS, INC. RESTRICTED STOCK UNIT AGREEMENT

Exhibit 10.4 ADTRAN HOLDINGS, INC. RESTRICTED STOCK UNIT AGREEMENT This Restricted Stock Unit Agreement (this “Agreement”) sets forth the specified terms of ADTRAN Holdings, Inc.’s grant of the number of Restricted Stock Units (“RSU”) as is set forth in the Morgan Stanley StockPlan Connect (the “Portal”) to the applicable grantee named in the Portal (the “Participant”) pursuant to the ADTRAN Holdi

May 5, 2026 EX-99.1

Condensed Consolidated Balance Sheets (In thousands)

ADTRAN Holdings, Inc. reports first quarter 2026 financial results Huntsville, Alabama, USA. — May 4, 2026 — ADTRAN Holdings, Inc. (NASDAQ: ADTN and FSE: QH9) (“ADTRAN Holdings” “ADTRAN” or the “Company”) today announced its unaudited financial results for the first quarter ended March 31, 2026. • Revenue: $286.1 million, up 15.5% year-over-year. • GAAP gross margin of 39.5%; Non-GAAP gross margin

May 5, 2026 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q

1 UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2026 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-41446 ADTRAN Holdings, Inc.

May 1, 2026 DEFA14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. ) Filed by the Registrant ☒    Filed by a party other than the Registrant  ☐ Check the appropriate box: ☐Preliminary Proxy Statement ☐Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ☐D

April 7, 2026 EX-10.1

SECOND AMENDMENT TO EMPLOYMENT AGREEMENT THE COMPANY: EXECUTIVE:

Exhibit 10.1 SECOND AMENDMENT TO EMPLOYMENT AGREEMENT This SECOND AMENDMENT TO EMPLOYMENT AGREEMENT (this “Amendment”) is entered into effective as of April 6, 2026, by and between Thomas R. Stanton, an individual resident of the State of Alabama (the “Executive”), and ADTRAN Holdings, Inc., a Delaware corporation (the “Company”). WHEREAS, the Executive, the Company, and ADTRAN, Inc., a Delaware c

April 7, 2026 8-K

FORM 8-K Item 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

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): April 01, 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 Fi

April 7, 2026 EX-10.3

Exhibit 10.3 * CERTAIN IDENTIFIED INFORMATION HAS BEEN EXCLUDED FROM THIS EXHIBIT BECAUSE IT IS NOT MATERIAL AND IS THE TYPE OF INFORMATION THE REGISTRANT CUSTOMARILY AND ACTUALLY TREATS AS PRIVATE AND CONFIDENTIAL. REDACTED INFORMATION IS INDICATED

Exhibit 10.3 * CERTAIN IDENTIFIED INFORMATION HAS BEEN EXCLUDED FROM THIS EXHIBIT BECAUSE IT IS NOT MATERIAL AND IS THE TYPE OF INFORMATION THE REGISTRANT CUSTOMARILY AND ACTUALLY TREATS AS PRIVATE AND CONFIDENTIAL. REDACTED INFORMATION IS INDICATED BY [***]. ADTRAN HOLDINGS, INC. 2026 T. STANTON 3-YEAR PERFORMANCE SHARES AGREEMENT This Performance Shares Agreement (this “Agreement”) sets forth th

April 7, 2026 EX-10.2

Exhibit 10.2 * CERTAIN IDENTIFIED INFORMATION HAS BEEN EXCLUDED FROM THIS EXHIBIT BECAUSE IT IS NOT MATERIAL AND IS THE TYPE OF INFORMATION THE REGISTRANT CUSTOMARILY AND ACTUALLY TREATS AS PRIVATE AND CONFIDENTIAL. REDACTED INFORMATION IS INDICATED

Exhibit 10.2 * CERTAIN IDENTIFIED INFORMATION HAS BEEN EXCLUDED FROM THIS EXHIBIT BECAUSE IT IS NOT MATERIAL AND IS THE TYPE OF INFORMATION THE REGISTRANT CUSTOMARILY AND ACTUALLY TREATS AS PRIVATE AND CONFIDENTIAL. REDACTED INFORMATION IS INDICATED BY [***]. ADTRAN HOLDINGS, INC. 2026 3-YEAR PERFORMANCE SHARES AGREEMENT This Performance Shares Agreement (this “Agreement”) sets forth the specified

March 27, 2026 DEFA14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A (Rule 14a-101) INFORMATION REQUIRED IN PROXY STATEMENT SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A (Rule 14a-101) INFORMATION REQUIRED IN PROXY STATEMENT SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ☒    Filed by a party other than the Registrant  ☐ Check the appropriate box:  ☐ Preliminary Proxy Statement  ☐ Confidential, for

March 27, 2026 DEF 14A

Notice of 2026 Annual Meeting and Proxy Statement Notice of Annual Meeting of Stockholders Table of Contents Proxy Statement for the Annual Meeting of Stockholders General Information about the Annual Meeting Security Ownership of Certain Beneficial

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No.  ) Filed by the Registrant ☒    Filed by a party other than the Registrant  ☐ Check the appropriate box: ☐ Preliminary Proxy Statement  ☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ☒

March 27, 2026 ARS

ARS

Adtran and the Adtran logo are registered trademarks of Adtranʟ ʼ n˖ʡ andʢ or its afЃ liates in the ˈʡˆʡ and other ˖ o˨ ntriesʡ ˇ o ˩ ie˪ a list of Adtran trademarksʟ go to this ˈ˅ʿʭ ˪˪˪ʡ adtranʡ com/trademarks.

March 13, 2026 PRE 14A

Notice of 2026 Annual Meeting and Proxy Statement Notice of Annual Meeting of Stockholders Table of Contents Proxy Statement for the Annual Meeting of Stockholders General Information about the Annual Meeting Security Ownership of Certain Beneficial

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No.  ) Filed by the Registrant ☒    Filed by a party other than the Registrant  ☐ Check the appropriate box:  ☒ Preliminary Proxy Statement  ☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

February 26, 2026 EX-10.1(V)

2026 ADTRAN VARIABLE INCENTIVE CASH COMPENSATION (VICC) PROGRAM PERFORMANCE MEASURES AND AWARDS For the year ending December 31, 2026

Adtran Confidential Exhibit 10.1 (v) * CERTAIN IDENTIFIED INFORMATION HAS BEEN EXCLUDED FROM THIS EXHIBIT BECAUSE IT IS NOT MATERIAL AND IS THE TYPE OF INFORMATION THE REGISTRANT CUSTOMARILY AND ACTUALLY TREATS AS PRIVATE AND CONFIDENTIAL. REDACTED INFORMATION IS INDICATED BY [***]. 2026 ADTRAN VARIABLE INCENTIVE CASH COMPENSATION (VICC) PROGRAM PERFORMANCE MEASURES AND AWARDS For the year ending

February 26, 2026 EX-10.1(Y)(VI)

DIENSTVERTRAGSÄNDERUNG VORSTANDSMITGLIED

Amendment to Officer’s Employment Agreement – Dienstvertragsänderung für Vorstandsmitglied Exhibit 10.

February 26, 2026 EX-19

What is Material Nonpublic Information (“MNPI”)? Insider Trading and Tipping Prohibitions Blackout Periods Permitted Transactions Rule 10b5-1(c) Trading Plans Additional Restrictions and Obligations for Section 16 Insiders and Closely Associated Pers

Exhibit 19 Adtran Holdings, Inc. Insider Trading Policy The purpose of this Adtran Holdings, Inc. Insider Trading Policy (this “Policy”) is to ensure compliance with the United States (“U.S.”) federal and state securities laws and the EU Market Abuse Regulation (the “MAR”) and all other appliable laws, which govern the rules regarding transacting in a company’s securities while in possession of ma

February 26, 2026 EX-99.2

Adtran Holdings (Nasdaq: ADTN) Investor presentation February 26, 2026

Adtran Holdings (Nasdaq: ADTN) Investor presentation February 26, 2026 Cautionary note regarding forward-looking statements This investor presentation contains forward-looking statements that are based on our management’s beliefs and assumptions and on information currently available to our management.

February 26, 2026 EX-10.1(C)

This document has not been approved by the Department of Labor, the Internal Revenue Service or any other governmental entity. The Employer must determine whether the plan is subject to the Federal securities laws and the securities laws of the vario

Page of 9 06499066.2 Exhibit 10.1(c) ADOPTION AGREEMENT ARTICLE 1 1.01 PLAN INFORMATION (a) Name of Plan: This is the ADTRAN Holdings, Inc. Deferred Compensation Program for Employees (the “Plan”). (b) Plan Status (Check one.): (1) Adoption Agreement effective date: 7/15/2022 . (2) The Adoption Agreement effective date is (Check (A) or check and complete (B)): (A) ☐ A new Plan effective date . (B)

February 26, 2026 EX-21

SUBSIDIARIES OF ADTRAN HOLDINGS, INC. December 31, 2025

Exhibit 21 SUBSIDIARIES OF ADTRAN HOLDINGS, INC. December 31, 2025 Name of Subsidiary Country or State of Incorporation ADTRAN Networks Pty. Ltd Australia ADTRAN Networks Comunicações Ltda. Brazil ADTRAN Canada, Inc. Canada ADTRAN d.o.o. Croatia ADTRAN, Inc. State of Delaware ADTRAN International, Inc. State of Delaware ADTRAN Networks Worldwide, Inc. State of Delaware ADTRAN Networks, LLC State o

February 26, 2026 EX-10.1(F)

ARTICLE II DEFINITIONS ARTICLE III ELIGIBILITY ARTICLE IV PARTICIPANT DEFERRALS ARTICLE V PARTICIPANT ACCOUNTS ARTICLE VI INVESTMENT OF ACCOUNTS ARTICLE VII RIGHT TO BENEFITS ARTICLE VIII DISTRIBUTION OF ACCOUNTS ARTICLE IX AMENDMENT AND TERMINATION

Page of 13 06507618.2 Exhibit 10.1(f) ADTRAN HOLDINGS, INC. EQUITY DEFERRAL PROGRAM FOR DIRECTORS ARTICLE I PREAMBLE ADTRAN Holdings, Inc. hereby restates the ADTRAN, Inc. Equity Deferral Program for Directors, which shall hereafter be named the ADTRAN Holdings, Inc. Equity Deferral Program for Directors (the “Plan”). This restatement shall be effective July 15, 2022. The Plan was originally adopt

February 26, 2026 EX-10.1(D)

This document has not been approved by the Department of Labor, the Internal Revenue Service or any other governmental entity. The Employer must determine whether the plan is subject to the Federal securities laws and the securities laws of the vario

Page of 9 06508005.1 Exhibit 10.1(d) ADOPTION AGREEMENT ARTICLE 1 1.01 PLAN INFORMATION (a) Name of Plan: This is the ADTRAN Holdings, Inc. Deferred Compensation Program for Directors (the “Plan”). (b) Plan Status (Check one.): (1) Adoption Agreement effective date: 7/15/2022 . (2) The Adoption Agreement effective date is (Check (A) or check and complete (B)): (A) ☐ A new Plan effective date . (B)

February 26, 2026 EX-99.1

Condensed Consolidated Balance Sheets (In thousands)

ADTRAN Holdings, Inc. reports fourth quarter and full year 2025 financial results Huntsville, Alabama, USA. — Feb. 25, 2026 — ADTRAN Holdings, Inc. (NASDAQ: ADTN and FSE: QH9) (“ADTRAN Holdings” “ADTRAN” or the “Company”) today announced its unaudited financial results for the fourth quarter ended December 31, 2025. • Revenue: $291.6 million, up 20.1% year-over-year. • GAAP gross margin of 39.0%;

February 26, 2026 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549. FORM 10-K

12liability of warranty UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.

February 26, 2026 8-K

FORM 8-K Item 2.02 Results of Operations and Financial Condition.

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): February 25, 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

February 26, 2026 EX-10.1(E)

ARTICLE II DEFINITIONS ARTICLE III ELIGIBILITY ARTICLE IV PARTICIPANT DEFERRALS ARTICLE V PARTICIPANT ACCOUNTS ARTICLE VI INVESTMENT OF ACCOUNTS ARTICLE VII RIGHT TO BENEFITS ARTICLE VIII DISTRIBUTION OF ACCOUNTS ARTICLE IX AMENDMENT AND TERMINATION

Page of 13 06502433.3 Exhibit 10.1(e) ADTRAN HOLDINGS, INC. EQUITY DEFERRAL PROGRAM FOR EMPLOYEES ARTICLE I PREAMBLE ADTRAN Holdings, Inc. hereby restates the ADTRAN, Inc. Equity Deferral Program for Employees, which shall hereafter be named the ADTRAN Holdings, Inc. Equity Deferral Program for Employees (the “Plan”). This restatement shall be effective July 15, 2022. The Plan was originally adopt

January 22, 2026 8-K

FORM 8-K Item 2.02 Results of Operations and Financial Condition.

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

January 22, 2026 EX-99.1

Reconciliation of Preliminary Operating Income (Loss) and Preliminary Operating Margin to Preliminary Non-GAAP Operating Income and Preliminary Non-GAAP Operating Margin (In millions)

EXHIBIT 99.1 ADTRAN Holdings, Inc. announces certain preliminary fourth quarter and full year 2025 results Huntsville, Alabama, USA. – January 21, 2026 — ADTRAN Holdings, Inc. (NASDAQ: ADTN and FSE: QH9) (“ADTRAN Holdings” or the “Company”) today announced preliminary unaudited revenue, as well as GAAP and non-GAAP operating margin, for the fiscal quarter and year ended December 31, 2025. This pre

January 22, 2026 EX-99.2

Reconciliation of Preliminary Operating Income (Loss) and Preliminary Operating Margin to Preliminary Non-GAAP Operating Income and Preliminary Non-GAAP Operating Margin (In millions)

EXHIBIT 99.2 Ad-hoc notification pursuant to Article 17 of Regulation (EU) No. 596/2014 ADTRAN Holdings, Inc.: Preliminary revenue above guidance and non-GAAP earnings per share above analyst consensus for Q4 2025 Huntsville, Alabama (United States of America). January 21, 2026 (CT) During the preparation of the report for the fourth quarter 2025 and fiscal year 2025 of ADTRAN Holdings, Inc. (“ADT

December 11, 2025 EX-10.1

DIENSTVERTRAGSÄNDERUNG VORSTANDSMITGLIED

Amendment to Officer’s Employment Agreement – Dienstvertragsänderung für Vorstandsmitglied Exhibit 10.

December 11, 2025 8-K

FORM 8-K Item 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers. Item 9.01 Financial Statements and Exhibits.

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): December 09, 2025 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission

November 4, 2025 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q

1 UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2025 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-41446 ADTRAN Holdings, Inc.

November 4, 2025 EX-99.2

Adtran Holdings (Nasdaq: ADTN) Investor presentation November 4, 2025

Adtran Holdings (Nasdaq: ADTN) Investor presentation November 4, 2025 Cautionary note regarding forward-looking statements This investor presentation contains forward-looking statements that are based on our management’s beliefs and assumptions and on information currently available to our management.

November 4, 2025 8-K

FORM 8-K Item 2.02 Results of Operations and Financial Condition.

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): November 03, 2025 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission

November 4, 2025 EX-99.1

About Adtran

ADTRAN Holdings, Inc. reports third quarter 2025 financial results Huntsville, Alabama, USA. — Nov. 3, 2025 — ADTRAN Holdings, Inc. (NASDAQ: ADTN and FSE: QH9) (“ADTRAN Holdings” “ADTRAN” or the “Company”) today announced its unaudited financial results for the third quarter ended September 30, 2025. • Revenue: $279.4 million, higher by 23% year-over-year. • Gross margin: GAAP gross margin of 38.3

September 22, 2025 EX-4.1

ADTRAN HOLDINGS, INC. U.S. BANK TRUST COMPANY, NATIONAL ASSOCIATION as Trustee Dated as of September 19, 2025 3.75% Convertible Senior Notes due 2030

Exhibit 4.1 Execution Version ═══════════════════════════════════════════════════════ ═══════════════════════════════════════════════════════ ADTRAN HOLDINGS, INC. and U.S. BANK TRUST COMPANY, NATIONAL ASSOCIATION as Trustee ───────────────────── INDENTURE Dated as of September 19, 2025 ───────────────────── 3.75% Convertible Senior Notes due 2030 ══════════════════════════════════════════════════

September 22, 2025 EX-10.1

[Signature Pages Follow.]

Exhibit 10.1 {Bidding Form} [DEALER]1 [  ], 2025 To: [  ] Re: [Base][Additional] Call Option Transaction The purpose of this letter agreement (this “Confirmation”) is to confirm the terms and conditions of the call option transaction entered into between [DEALER] (“Dealer”)[, represented by [AGENT] (“Agent”),] and ADTRAN Holdings, Inc. (“Counterparty”) as of the Trade Date specified below (the “

September 22, 2025 8-K

FORM 8-K Item 1.01 Entry into a Material Definitive Agreement.

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): September 19, 2025 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commissio

September 17, 2025 EX-99.1

ADTRAN Holdings, Inc. Announces Proposed Convertible Senior Notes Offering

Exhibit 99.1 ADTRAN Holdings, Inc. Announces Proposed Convertible Senior Notes Offering HUNTSVILLE, Ala.—September 15, 2025—ADTRAN Holdings, Inc. (NASDAQ: ADTN and FSE: QH9) (the “Company”) today announced its intention to offer, subject to market and other conditions, $150,000,000 aggregate principal amount of convertible senior notes due 2030 (the “Notes”) in a private offering to persons reason

September 17, 2025 8-K

FORM 8-K Item 1.01. Entry into a Material Definitive Agreement

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): September 15, 2025 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commissio

September 17, 2025 EX-99.2

ADTRAN Holdings, Inc. Prices Upsized $175.0 Million Convertible Senior Notes Offering

Exhibit 99.2 ADTRAN Holdings, Inc. Prices Upsized $175.0 Million Convertible Senior Notes Offering HUNTSVILLE, Ala.—September 17, 2025—ADTRAN Holdings, Inc. (NASDAQ: ADTN and FSE: QH9) (the “Company”) today announced the pricing of its offering of $175.0 million aggregate principal amount of 3.75% convertible senior notes due 2030 (the “Notes”) in a private offering to persons reasonably believed

September 17, 2025 EX-10.2

[Signature Pages Follow.]

Exhibit 10.2 (Bidding Form) [DEALER]1 [  ], 2025 To: ADTRAN Holdings, Inc. 901 Explorer Boulevard Huntsville, Alabama 35806 Attention: Timothy Santo Telephone No.: [email protected] Re: [Base][Additional] Call Option Transaction The purpose of this letter agreement (this “Confirmation”) is to confirm the terms and conditions of the call option transaction entered into between [DEALER] (“De

September 17, 2025 EX-10.1

SIXTH AMENDMENT AND CONSENT TO CREDIT AGREEMENT

Exhibit 10.1 EXECUTION VERSION SIXTH AMENDMENT AND CONSENT TO CREDIT AGREEMENT SIXTH AMENDMENT AND CONSENT TO CREDIT AGREEMENT (this “Amendment”), dated as of September 16, 2025, among ADTRAN, INC., a Delaware corporation (the “US Borrower”), ADTRAN NETWORKS SE, a European stock corporation incorporated under the law of the European Union and Germany (“ADVA”), ADTRAN HOLDINGS, INC., a Delaware cor

August 5, 2025 EX-10.1

Settlement Agreement, dated May 12, 2025, by and between Adtran Networks SE and Ulrich Dopfer

Exhibit 10.1 SETTLEMENT AGREEMENT between Adtran Networks SE Marzenquelle 1-3 98617 Meiningen OT Drei6igacker Germany (hereinafter the "Company") represented by its supervisory board, which again is represented by its chainnan, Dr. Eduard Scheiterer and Mr. Ulrich Dopfer (hereinafter ,,Mr. Dopfer") (the Company and Mr. Dopfer together hereinafter also the "Parties") Preamble Mr. Dopfer has been a

August 5, 2025 EX-99.2

Adtran Holdings (Nasdaq: ADTN) Investor Presentation August 5, 2025

Adtran Holdings (Nasdaq: ADTN) Investor Presentation August 5, 2025 Cautionary note regarding forward-looking statements This investor presentation contains forward-looking statements that are based on our management’s beliefs and assumptions and on information currently available to our management.

August 5, 2025 8-K

FORM 8-K Item 2.02 Results of Operations and Financial Condition.

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): August 04, 2025 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission F

August 5, 2025 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q

1 UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2025 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-41446 ADTRAN Holdings, Inc.

August 5, 2025 EX-10.2

Form of Restricted Stock Unit Agreement for CEO under the ADTRAN Holdings, Inc. 2024 Employee Stock Incentive Plan

Exhibit 10.2 ADTRAN HOLDINGS, INC. T. STANTON RESTRICTED STOCK UNIT AGREEMENT This Restricted Stock Unit Agreement (this “Agreement”) sets forth the specified terms of ADTRAN Holdings, Inc.’s grant of the number of Restricted Stock Units (“RSU”) as is set forth in the Morgan Stanley StockPlan Connect (the “Portal”) to the applicable grantee named in the Portal (the “Participant”) pursuant to the A

August 5, 2025 EX-99.1

Conference call Upcoming conference schedule About Adtran Cautionary note regarding forward-looking statements Explanation of use of non-GAAP financial measures

ADTRAN Holdings, Inc. reports second quarter 2025 financial results Huntsville, Alabama, USA. — Aug. 4, 2025 — ADTRAN Holdings, Inc. (NASDAQ: ADTN and FSE: QH9) (“ADTRAN Holdings” “ADTRAN” or the “Company”) today announced its unaudited financial results for the second quarter ended June 30, 2025. • Revenue: $265.1 million, higher by 17% year-over-year. • Gross margin: GAAP gross margin: 37.3%; no

August 5, 2025 EX-10.4

Form of Performance Share Agreement for CEO under the ADTRAN Holdings, Inc. 2024 Employee Stock Incentive Plan

Exhibit 10.4 ADTRAN HOLDINGS, INC. T. STanton PERFORMANCE SHARES AGREEMENT This Performance Shares Agreement (this “Agreement”) sets forth the specified terms of ADTRAN Holdings, Inc.’s grant of the number of Restricted Stock Units (“Performance Shares”) as it set forth in the Morgan Stanley StockPlan Connect (the “Portal”) to the applicable grantee named in the Portal (the “Participant”) pursuant

August 5, 2025 EX-10.3

Form of Market-Based Performance Stock Unit Agreement for CEO under the ADTRAN Holdings, Inc. 2024 Employee Stock Incentive Plan

Exhibit 10.3 ADTRAN HOLDINGS, INC. T. STANTON 2025 MARKET-BASED PERFORMANCE STOCK UNIT AGREEMENT This Market-Based Performance Stock Unit Agreement (this “Agreement”) sets forth the specified terms of ADTRAN Holdings, Inc.’s grant of the target number of Market-Based Performance Stock Units (“PSUs”) set forth in the Morgan Stanley StockPlan Connect (the “Portal”) to the applicable grantee named in

July 30, 2025 8-K

Financial Statements and Exhibits, Other Events, Submission of Matters to a Vote of Security Holders

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): July 24, 2025 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission Fil

July 17, 2025 8-K/A

Regulation FD Disclosure, Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K/A CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): July 16, 2025 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission F

July 17, 2025 EX-99.1

The Company will webcast this conference call, or you may dial in to participate. To listen, visit the events and presentations section of ADTRAN Holdings, Inc. Investor Relations site at https://events.q4inc.com/attendee/260991346 approximately 10 m

EXHIBIT 99.1 ADTRAN Holdings, Inc. announces higher than expected preliminary Q2 2025 revenue Huntsville, Alabama, USA. – July 16, 2025 — ADTRAN Holdings, Inc. (NASDAQ: ADTN and FSE: QH9) (“ADTRAN Holdings” or the “Company”) today announced preliminary unaudited revenue for the quarter ended June 30, 2025. All figures in this release are approximate due to the preliminary nature of the announcemen

July 17, 2025 EX-99.2

EX-99.2

EXHIBIT 99.2 Ad-hoc notification pursuant to Article 17 of Regulation (EU) No. 596/2014 ADTRAN Holdings, Inc.: Preliminary Q2 2025 revenue above prior guidance range Huntsville, Alabama (United States of America). July 16, 2025 (CT) During the preparation of the report for the second quarter 2025 of ADTRAN Holdings, Inc. (“ADTRAN Holdings” or the “Company”) (NASDAQ: ADTN; FSE: QH9), the Company de

July 16, 2025 8-K

FORM 8-K Item 2.02 Results of Operations and Financial Condition. On July 16, 2025, ADTRAN Holdings, Inc. (“ADTRAN”) announced its preliminary revenue for the fiscal quarter ended June 30, 2025. A copy of ADTRAN’s press release announcing ADTRAN's pr

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): July 16, 2025 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission Fil

July 16, 2025 EX-99.2

EX-99.2

EXHIBIT 99.2 Ad-hoc notification pursuant to Article 17 of Regulation (EU) No. 596/2014 ADTRAN Holdings, Inc.: Preliminary Q2 2025 revenue above prior guidance range Huntsville, Alabama (United States of America). July 16, 2025 (CT) During the preparation of the report for the second quarter 2025 of ADTRAN Holdings, Inc. (“ADTRAN Holdings” or the “Company”) (NASDAQ: ADTN; FSE: QH9), the Company de

July 16, 2025 EX-99.1

The Company will webcast this conference call, or you may dial in to participate. To listen, visit the events and presentations section of ADTRAN Holdings, Inc. Investor Relations site at https://events.q4inc.com/attendee/260991346 approximately 10 m

EXHIBIT 99.1 ADTRAN Holdings, Inc. announces higher than expected preliminary Q2 2025 revenue Huntsville, Alabama, USA. – July 16, 2025 — ADTRAN Holdings, Inc. (NASDAQ: ADTN and FSE: QH9) (“ADTRAN Holdings” or the “Company”) today announced preliminary unaudited revenue for the quarter ended June 30, 2025. All figures in this release are approximate due to the preliminary nature of the announcemen

June 30, 2025 11-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 11-K [X] ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2024 [ ] TRANSITION REPORT PURSUANT TO SECTION

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 11-K [X] ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2024 OR [ ] TRANSITION REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number 001-41446 ADTRAN, Inc. 401(k) RETIREMENT PLA

June 6, 2025 DEFA14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A (Rule 14a-101) INFORMATION REQUIRED IN PROXY STATEMENT SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Ame

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A (Rule 14a-101) INFORMATION REQUIRED IN PROXY STATEMENT SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. 1) Filed by the Registrant ☒    Filed by a party other than the Registrant  ☐ Check the appropriate box:  ☐ Preliminary Proxy Statement  ☐

June 6, 2025 ARS/A

ARS/A

June 6, 2025 DEFR14A

Notice of 2025 Annual Meeting and Proxy Statement Notice of Annual Meeting of Stockholders Table of Contents Proxy Statement for the Annual Meeting of Stockholders General Information about the Annual Meeting Security Ownership of Certain Beneficial

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. 1) Filed by the Registrant ☒    Filed by a party other than the Registrant  ☐ Check the appropriate box:  ☐ Preliminary Proxy Statement  ☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

May 29, 2025 SD

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM SD Specialized Disclosure Report ADTRAN Holdings, Inc. (Exact name of Registrant as specified in its charter)

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM SD Specialized Disclosure Report ADTRAN Holdings, Inc. (Exact name of Registrant as specified in its charter) Delaware (State of Incorporation) 001-41446 (Commission file number) 87-2164282 (I.R.S. Employer Identification Number) 901 Explorer Boulevard, Huntsville, Alabama 35806-2807 (Address of principal executive office

May 29, 2025 EX-1.01

Exhibit 1.01 – Conflict Minerals Report as required by Items 1.01 and 1.02 of this Form.

Exhibit 1.01 Conflict Minerals Report of ADTRAN Holdings, Inc. Company Overview ADTRAN Holdings, Inc. (NASDAQ:ADTN) (“ADTRAN” or the “Company”) is a leading global provider of networking and communications platforms, software, systems and services focused on the broadband access market, serving a diverse domestic and international customer base in multiple countries that includes large, medium and

May 28, 2025 EX-99.1

Supplemental Non-GAAP Financial Measures

Exhibit 99.1 Supplemental Non-GAAP Financial Measures ADTRAN Holdings, Inc. (the “Company”) is providing the following tables to present certain non-GAAP information for the reporting periods covered in the Company’s Annual Report on Form 10-K/A for the year ended December 31, 2024 (the “Amended Form 10-K”) and the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2025 (the “

May 28, 2025 EX-99.2

Adtran Holdings (Nasdaq: ADTN) Investor Presentation May 27, 2025

Adtran Holdings (Nasdaq: ADTN) Investor Presentation May 27, 2025 Cautionary note regarding forward-looking statements This investor presentation contains forward-looking statements that are based on our management’s beliefs and assumptions and on information currently available to our management.

May 28, 2025 8-K

Financial Statements and Exhibits, Results of Operations and Financial Condition

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): May 27, 2025 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

May 27, 2025 8-K

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): May 27, 2025 ADTRAN Holdings, Inc

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): May 27, 2025 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

May 27, 2025 EX-99.1

ADTRAN Holdings, Inc. announces date of 2025 annual meeting of stockholders

EX-99.1 Exhibit 99.1 ADTRAN Holdings, Inc. announces date of 2025 annual meeting of stockholders Huntsville, Alabama, USA. — May 27, 2025 — ADTRAN Holdings, Inc. (NASDAQ: ADTN and FSE: QH9) (“ADTRAN Holdings” or the “Company”) today announced that its previously postponed 2025 annual meeting of stockholders (the “Annual Meeting”) has been rescheduled for Thursday, July 24, 2025. The Company intend

May 27, 2025 DEFA14A

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): May 27, 2025 ADTRAN Holdings, Inc

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): May 27, 2025 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

May 20, 2025 EX-10.1(Z)

Form of Restricted Stock Unit Agreement under the ADTRAN Holdings, Inc. 2024 Employee Stock Incentive Plan

Exhibit 10.1(z) ADTRAN HOLDINGS, INC. FORM of RESTRICTED STOCK UNIT AGREEMENT This Restricted Stock Unit Agreement (this “Agreement”) sets forth the specified terms of ADTRAN Holdings, Inc.’s grant of the number of Restricted Stock Units (“RSU”) as is set forth in the Morgan Stanley StockPlan Connect (the “Portal”) to the applicable grantee named in the Portal (the “Participant”) pursuant to the A

May 20, 2025 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q

1 UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2025 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-41446 ADTRAN Holdings, Inc.

May 20, 2025 EX-10.3

EX-10.3

May 20, 2025 10-K/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K/A

12liability of warranty UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.

May 13, 2025 DEFA14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A (Rule 14a-101) INFORMATION REQUIRED IN PROXY STATEMENT SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A (Rule 14a-101) INFORMATION REQUIRED IN PROXY STATEMENT SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ☒    Filed by a party other than the Registrant  ☐ Check the appropriate box: ☐Preliminary Proxy Statement ☐Confidential, for Us

May 13, 2025 NT 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 12b-25 NOTIFICATION OF LATE FILING

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 12b-25 NOTIFICATION OF LATE FILING SEC File Number 001-41446 CUSIP Number 00486H105 (Check One) ☐ Form 10-K ☐ Form 20-F ☐ Form 11-K ☒ Form 10-Q ☐ Form 10-D ☐ Form N-CEN ☐ Form N-CSR For Period Ended: March 31, 2025 ☐ Transition Report on Form 10-K ☐ Transition Report on Form 20-F ☐ Transition Report on Form 11-K ☐ Transit

May 13, 2025 8-K

Financial Statements and Exhibits, Non-Reliance on Previously Issued Financial Statements or a Related Audit Report or Completed Interim Review, Other Events

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): May 13, 2025 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

May 12, 2025 8-K

Entry into a Material Definitive Agreement, Financial Statements and Exhibits

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): May 06, 2025 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

May 12, 2025 EX-10.1

Fifth Amendment to Credit Agreement and Waiver, by and between ADTRAN, Inc., Adtran Networks, SE and Wells Fargo Bank, National Association, dated May 6, 2025

Exhibit 10.1 Execution Version FIFTH AMENDMENT TO CREDIT AGREEMENT AND WAIVER FIFTH AMENDMENT TO CREDIT AGREEMENT AND WAIVER (this “Amendment”), dated as of May 6, 2025, among ADTRAN, INC., a Delaware corporation (the “US Borrower”), ADTRAN NETWORKS SE, a European stock corporation incorporated under the law of the European Union and Germany (“ADVA”), ADTRAN HOLDINGS, INC., a Delaware corporation

May 8, 2025 EX-99.1

ADTRAN Holdings, Inc. reports preliminary first quarter 2025 financial results

ADTRAN Holdings, Inc. reports preliminary first quarter 2025 financial results Huntsville, Alabama, USA. — May 7, 2025 — ADTRAN Holdings, Inc. (NASDAQ: ADTN and FSE: QH9) (“ADTRAN Holdings” or the “Company”) today announced its preliminary unaudited financial results for the first quarter ended March 31, 2025. • Revenue: $247.7 million, higher by 10% year-over-year, and above the mid-point of outl

May 8, 2025 8-K

Regulation FD Disclosure, Financial Statements and Exhibits, Results of Operations and Financial Condition

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): May 07, 2025 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

May 8, 2025 EX-99.2

Adtran Holdings (Nasdaq: ADTN) Investor Presentation May 7, 2025

Adtran Holdings (Nasdaq: ADTN) Investor Presentation May 7, 2025 Cautionary note regarding forward-looking statements Statements contained in this investor presentation which are not historical facts, such as those relating to expectations regarding future revenue and future non-GAAP operating margin; future service provider spending; future profitability, and growth, including customer acquisition and booking trends, as well as future end market growth; future market trends and customer inventory levels; future operational leverage and cash generation; and ADTRAN Holdings’ strategy and outlook, outlook and financial guidance, are forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995.

April 16, 2025 EX-99.1

notification pursuant to Article 17 of the Market-Abuse-Regulation (EU) No. 596/2024

Exhibit 99.1 Ad-hoc notification pursuant to Article 17 of the Market-Abuse-Regulation (EU) No. 596/2024 Adtran Networks SE: Adtran Networks SE updates preliminary results for the financial year 2024 Munich, Germany. April 15, 2025. The Management Board of Adtran Networks SE today reassessed the IFRS pro forma EBIT expectations for the financial year 2024. In the course of the finalization of the

April 16, 2025 8-K

Regulation FD Disclosure

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): April 15, 2025 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission Fi

March 31, 2025 DEFA14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A (Rule 14a-101) INFORMATION REQUIRED IN PROXY STATEMENT SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A (Rule 14a-101) INFORMATION REQUIRED IN PROXY STATEMENT SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ☒    Filed by a party other than the Registrant  ☐ Check the appropriate box:  ☐ Preliminary Proxy Statement  ☐ Confidential, for

March 31, 2025 DEF 14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No.  )

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No.  ) Filed by the Registrant ☒    Filed by a party other than the Registrant  ☐ Check the appropriate box:  ☐ Preliminary Proxy Statement  ☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

March 31, 2025 ARS

ARS

Adtran and the Adtran logo are registered trademarks of Adtranʟ ʼ n˖ʡ andʢ or its afЃ liates in the ˈʡˆʡ and other ˖ o˨ ntriesʡ ˇ o ˩ ie˪ a list of Adtran trademarksʟ go to this ˈ˅ʿʭ ˪˪˪ʡ adtranʡ com/trademarks.

March 7, 2025 EX-99.1

ADTRAN Holdings, Inc. announces CFO transition

Exhibit 99.1 ADTRAN Holdings, Inc. announces CFO transition Timothy Santo, CPA, accomplished finance and accounting executive with extensive public company experience, named CFO; Uli Dopfer to transition to new role Huntsville, Alabama, USA. — March 6, 2025 — ADTRAN Holdings, Inc. (NASDAQ: ADTN and FSE: QH9) (“ADTRAN Holdings” or the “Company”) today announced a Chief Financial Officer transition.

March 7, 2025 EX-10.1

Offer Letter, dated February 28, 2025, by and between ADTRAN Holdings, Inc. and Timothy Santo

Exhibit 10.1 February 28, 2025 Timothy Santo [Address] Dear Tim, We are pleased to extend to you the following offer of employment with Adtran, Inc. as Senior Vice President, Finance and Chief Financial Officer, reporting to Tom Stanton, CEO, located at Adtran’s headquarters in Huntsville, Alabama. Your compensation will include a bi-weekly paid salary of $17,692 (gross) resulting in an annualized

March 7, 2025 8-K

Regulation FD Disclosure

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): March 6, 2025 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission Fil

March 3, 2025 EX-4.1

Description of Securities

Exhibit 4.1 DESCRIPTION OF THE REGISTRANT’S SECURITIES REGISTERED PURSUANT TO SECTION 12 OF THE SECURITIES EXCHANGE ACT OF 1934 The following description of our securities is intended as a summary only. This description is based the certificate of incorporation, as amended (the “Certificate of Incorporation”) of ADTRAN Holdings, Inc. (the “Company,” “we,” “us,” and “our”), the Company’s bylaws, as

March 3, 2025 EX-10.1(Y)

Form of Market-Based Performance Stock Unit Agreement under the ADTRAN Holdings, Inc. 2024 Employee Stock Incentive Plan

Exhibit 10.1 (y) ADTRAN HOLDINGS, INC. FORM OF MARKET-BASED PERFORMANCE STOCK UNIT AGREEMENT This Market-Based Performance Stock Unit Agreement (this “Agreement”) sets forth the specified terms of ADTRAN Holdings, Inc.’s grant of the target number of Market-Based Performance Stock Units (“PSUs”) set forth in the Morgan Stanley StockPlan Connect (the “Portal”) to the applicable grantee named in the

March 3, 2025 EX-19

ADTRAN Holdings, Inc. Insider Trading Policy

ADTRAN HOLDINGS, INC. INSIDER TRADING POLICY Effective October 29, 2024 I. INTRODUCTION United States (“U.S.”) federal and state securities laws and European Regulation No. 596/2014 (the “EU Market Abuse Regulation” or the “MAR”) prohibit buying, selling, or making other transfers of securities by persons who possess (i) material information that is not generally known or available to the public (

March 3, 2025 EX-10.1(U)

Form of 2025 Variable Incentive Compensation Plan Award Letter

Exhibit 10.1 (u) * CERTAIN IDENTIFIED INFORMATION HAS BEEN EXCLUDED FROM THIS EXHIBIT BECAUSE IT IS NOT MATERIAL AND IS THE TYPE OF INFORMATION THE REGISTRANT CUSTOMARILY AND ACTUALLY TREATS AS PRIVATE AND CONFIDENTIAL. REDACTED INFORMATION IS INDICATED BY [***]. Form of VICC Award Letter Date Dear Executive, I am pleased to inform you that you have been selected to participate in the Adtran Incen

March 3, 2025 EX-24

Powers of Attorney.

Exhibit 24 POWER OF ATTORNEY KNOW ALL MEN BY THESE PRESENTS, that each of the undersigned, being a director of ADTRAN Holdings, Inc.

March 3, 2025 EX-10.1(Z)

ADTRAN HOLDINGS, INC. FORM of RESTRICTED STOCK UNIT AGREEMENT

Exhibit 10.1(z) ADTRAN HOLDINGS, INC. FORM of RESTRICTED STOCK UNIT AGREEMENT This Restricted Stock Unit Agreement (this “Agreement”) sets forth the specified terms of ADTRAN Holdings, Inc.’s grant of the number of Restricted Stock Units (“RSU”) as is set forth in the Morgan Stanley StockPlan Connect (the “Portal”) to the applicable grantee named in the Portal (the “Participant”) pursuant to the A

March 3, 2025 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K

12liability of warranty UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.

March 3, 2025 EX-21

Subsidiaries of Adtran.

Exhibit 21 SUBSIDIARIES OF ADTRAN HOLDINGS, INC. December 31, 2024 Name of Subsidiary Country or State of Incorporation ADTRAN Networks Pty. Ltd Australia ADTRAN Networks Comunicações Ltda. Brazil ADTRAN Canada, Inc. Canada ADTRAN d.o.o. Croatia ADTRAN, Inc. State of Delaware ADTRAN International, Inc. State of Delaware ADTRAN Networks Worldwide, Inc. State of Delaware ADTRAN Networks, LLC State o

February 27, 2025 EX-99.2

Adtran Holdings (Nasdaq: ADTN) Investor Presentation February 26, 2025

Adtran Holdings (Nasdaq: ADTN) Investor Presentation February 26, 2025 Cautionary note regarding forward-looking statements Statements contained in this investor presentation which are not historical facts, such as those relating to expectations regarding future revenue and future non-GAAP operating margin; future service provider spending; future profitability, and growth, including customer acquisition and booking trends, as well as future end market growth; future market trends and customer inventory levels; future operational leverage and cash generation; and ADTRAN Holdings’ strategy and outlook, outlook and financial guidance, are forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995.

February 27, 2025 EX-99.1

Condensed Consolidated Balance Sheets (Preliminary, Unaudited) (In thousands)

ADTRAN Holdings, Inc. reports preliminary fourth quarter and full-year 2024 financial results Huntsville, Alabama, USA. — February 26, 2025 — ADTRAN Holdings, Inc. (NASDAQ: ADTN and FSE: QH9) (“ADTRAN Holdings” or the “Company”) today announced its preliminary unaudited financial results for the fourth quarter and full-year ended December 31, 2024. • Revenue: $242.9 million, up 7% sequentially and

February 27, 2025 8-K

Regulation FD Disclosure, Financial Statements and Exhibits, Results of Operations and Financial Condition

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): February 26, 2025 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission

February 14, 2025 EX-1

ADTN / ADTRAN Holdings, Inc. / Divisar Capital Management LLC

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November 22, 2024 CORRESP

November 22, 2024 VIA EDGAR United States Securities and Exchange Commission Division of Corporation Finance 100 F Street, N.E. Washington, DC 20549 Attention: Sarah Sidwell Re: ADTRAN Holdings, Inc. Registration Statement on Form

November 22, 2024 VIA EDGAR United States Securities and Exchange Commission Division of Corporation Finance 100 F Street, N.

November 21, 2024 LETTER

LETTER

November 21, 2024 Ulrich Dopfer Chief Financial Officer ADTRAN Holdings, Inc. 901 Explorer Boulevard Huntsville, Alabama 35806-2807 Re: ADTRAN Holdings, Inc. Registration Statement on Form S-3 Filed on November 18, 2024 File No. 333-283311 Dear Ulrich Dopfer: This is to advise you that we have not reviewed and will not review your registration statement. Please refer to Rules 460 and 461 regarding

November 18, 2024 EX-24.1

Powers of Attorney

EX-24.1 Exhibit 24.1 POWER OF ATTORNEY KNOW ALL MEN BY THESE PRESENTS, THAT: The undersigned director of ADTRAN Holdings, Inc. (the “Company”) constitutes and appoints Thomas R. Stanton and Ulrich Dopfer, and each of them severally, his true and lawful attorneys-in-fact and agents with full and several power of substitution, for him and in his name, place and stead, in any and all capacities, to s

November 18, 2024 EX-FILING FEES

Filing Fee Table

Exhibit 107 Calculation of Filing Fee Tables Form S-3 (Form Type) ADTRAN Holdings, Inc.

November 18, 2024 S-3

As filed with the Securities and Exchange Commission on November 18, 2024

S-3 Table of Contents As filed with the Securities and Exchange Commission on November 18, 2024 Registration No.

November 14, 2024 EX-1

ADTN / ADTRAN Holdings, Inc. / Divisar Capital Management LLC

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November 14, 2024 SC 13G/A

ADTN / ADTRAN Holdings, Inc. / WILLIAM BLAIR INVESTMENT MANAGEMENT, LLC - SC 13G/A Passive Investment

SC 13G/A 1 tm2428293d9sc13ga.htm SC 13G/A UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G* (Rule 13d-102) INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO § 240.13d-1(b), (c), AND (d) AND AMENDMENTS THERETO FILED PURSUANT TO § 240.13d-2 (Amendment No. 1)* ADTRAN Holdings Inc (Name of Issuer) Common Stock (Title of Class of Securities) 00486H105 (CUSIP

November 12, 2024 SC 13G/A

ADTN / ADTRAN Holdings, Inc. / VANGUARD GROUP INC Passive Investment

SC 13G/A 1 UnitedStates13GADTRANHold.txt 240.13d-102 Schedule 13G - Information to be included in statements filed pursuant to 240.13d-1(b), (c), and (d) and amendments thereto filed pursuant to 240.13d-2. Securities and Exchange Commission, Washington, D.C. 20549 Schedule 13G Under the Securities Exchange Act of 1934 (Amendment No. 16)* (Name of Issuer) ADTRAN Holdings Inc (Title of Class of Secu

November 12, 2024 SC 13G

ADTN / ADTRAN Holdings, Inc. / DnB Asset Management AS - SCHEDULE 13G Passive Investment

SC 13G 1 sc13g.htm SCHEDULE 13G SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 SCHEDULE 13G INFORMATION STATEMENT PURSUANT TO RULES 13d-1 AND 13d-2 UNDER THE SECURITIES EXCHANGE ACT OF 1934 ADTRAN Holdings, Inc. (Name of Issuer) Common Stock, Par Value $0.01 per share (Title of Class of Securities) 00486H105 (CUSIP Number) September 30, 2024 (Date of Event Which Requires Filing of This St

November 12, 2024 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q

1 UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2024 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-41446 ADTRAN Holdings, Inc.

November 7, 2024 EX-99.1

Condensed Consolidated Balance Sheets (Preliminary, Unaudited) (In thousands)

EXHIBIT 99.1 ADTRAN Holdings, Inc. reports preliminary third quarter 2024 financial results Huntsville, Alabama, USA. — November 06, 2024 — ADTRAN Holdings, Inc. (NASDAQ: ADTN and FSE: QH9) (“ADTRAN Holdings” or the “Company”) today announced its preliminary unaudited financial results for the third quarter of 2024. • Revenue: $227.7 million, up sequentially and above the mid-point of guidance. •

November 7, 2024 8-K

Regulation FD Disclosure, Financial Statements and Exhibits, Results of Operations and Financial Condition

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): November 06, 2024 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission

November 7, 2024 EX-99.2

Adtran Holdings (Nasdaq: ADTN) Investor Presentation November 6, 2024

Adtran Holdings (Nasdaq: ADTN) Investor Presentation November 6, 2024 Cautionary Note Regarding Forward-Looking Statements Statements contained in this investor presentation which are not historical facts, such as those relating to expectations regarding future revenue and future non-GAAP operating margin; future service provider spending; future profitability, and growth, including customer acquisition and booking trends, as well as future end market growth; future market trends and customer inventory levels; future operational leverage and cash generation; and ADTRAN Holdings’ strategy and outlook, outlook and financial guidance, are forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995.

November 4, 2024 SC 13G

ADTN / ADTRAN Holdings, Inc. / VANGUARD GROUP INC Passive Investment

SC 13G 1 UnitedStates13GADTRANHold.txt 240.13d-102 Schedule 13G - Information to be included in statements filed pursuant to 240.13d-1(b), (c), and (d) and amendments thereto filed pursuant to 240.13d-2. Securities and Exchange Commission, Washington, D.C. 20549 Schedule 13G Under the Securities Exchange Act of 1934 (Amendment No. 15)* (Name of Issuer) ADTRAN Holdings Inc (Title of Class of Securi

November 4, 2024 LETTER

LETTER

November 4, 2024 Ulrich Dopfer Chief Financial Officer ADTRAN Holdings, Inc. 901 Explorer Boulevard Huntsville, AL 35806 Re: ADTRAN Holdings, Inc. Form 10-K for Fiscal Year Ended December 31, 2023 File No. 001-41446 Dear Ulrich Dopfer: We have completed our review of your filing. We remind you that the company and its management are responsible for the accuracy and adequacy of their disclosures, n

September 27, 2024 CORRESP

CORRESP

September 27, 2024 VIA EDGAR Securities and Exchange Commission Division of Corporation Finance 100 F Street, N.

September 27, 2024 CORRESP

September 27, 2024

September 27, 2024 VIA EDGAR Securities and Exchange Commission Division of Corporation Finance 100 F Street, N.

September 26, 2024 LETTER

LETTER

September 25, 2024 Ulrich Dopfer Chief Financial Officer ADTRAN Holdings, Inc. 901 Explorer Boulevard Huntsville, AL 35806 Re: ADTRAN Holdings, Inc. Form 10-K for Fiscal Year Ended December 31, 2023 File No. 001-41446 Dear Ulrich Dopfer: We have reviewed your filing and have the following comment. Please respond to this letter within ten business days by providing the requested information or advi

August 30, 2024 EX-10.2

Tenth Amendment Employment Agreement, dated August 27, 2024, by and between Adtran Networks SE and Ulrich Dopfer (incorporated by reference to Exhibit 10.2 to the Company's Form 8-K filed August 30, 2024)

EXHIBIT 10.2 * CERTAIN IDENTIFIED INFORMATION HAS BEEN EXCLUDED FROM THIS EXHIBIT BECAUSE IT IS NOT MATERIAL AND IS THE TYPE OF INFORMATION THE REGISTRANT CUSTOMARILY AND ACTUALLY TREATS AS PRIVATE AND CONFIDENTIAL. REDACTED INFORMATION IS INDICATED BY [***]. Amendment to Officer’s Employment Agreement – Dienstvertragsänderung für Vorstandsmitglied AMENDMENT TO OFFICER`S EMPLOYMENT AGREEMENT DIENS

August 30, 2024 8-K

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Financial Statements and Exhibits

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): August 27, 2024 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission F

August 30, 2024 EX-10.1

Nineteenth Amendment to Employment Agreement, dated August 27, 2024, by and between Adtran Networks SE and Christoph Glingener

EXHIBIT 10.1 * CERTAIN IDENTIFIED INFORMATION HAS BEEN EXCLUDED FROM THIS EXHIBIT BECAUSE IT IS NOT MATERIAL AND IS THE TYPE OF INFORMATION THE REGISTRANT CUSTOMARILY AND ACTUALLY TREATS AS PRIVATE AND CONFIDENTIAL. REDACTED INFORMATION IS INDICATED BY [***]. Amendment to Officer’s Employment Agreement – Dienstvertragsänderung für Vorstandsmitglied AMENDMENT TO OFFICER`S EMPLOYMENT AGREEMENT DIENS

August 9, 2024 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q

1 UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2024 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-41446 ADTRAN Holdings, Inc.

August 6, 2024 EX-99.1

Condensed Consolidated Balance Sheets (In thousands)

ADTRAN Holdings, Inc. reports second quarter 2024 financial results Huntsville, Alabama, USA. — August 05, 2024 — ADTRAN Holdings, Inc. (NASDAQ: ADTN and FSE: QH9) (“ADTRAN Holdings” or the “Company”) today announced its unaudited financial results for the second quarter of 2024. • Revenue: $226.0 million • Gross margin: o GAAP gross margin: 36.1%; Non-GAAP gross margin: 41.9% • Operating margin:

August 6, 2024 EX-99.2

Adtran Holdings Investor presentation August 6, 2024

Adtran Holdings Investor presentation August 6, 2024 Cautionary note regarding forward-looking statements Statements contained in this investor presentation which are not historical facts, such as those relating to expectations regarding future revenues; ADTRAN Holdings ability to reduce its inventory levels; ADTRAN Holdings’ potential funding opportunities; and ADTRAN Holdings’ strategy and outlook, outlook and financial guidance, are forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995.

August 6, 2024 8-K

Regulation FD Disclosure, Financial Statements and Exhibits, Results of Operations and Financial Condition

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): August 05, 2024 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission F

August 2, 2024 8-K

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers

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): July 31, 2024 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission Fil

July 8, 2024 SC 13G/A

ADTN / ADTRAN Holdings, Inc. / BlackRock Inc. Passive Investment

SC 13G/A 1 us00486h1059070824.txt us00486h1059070824.txt SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No: 3) ADTRAN HOLDINGS, INC. - (Name of Issuer) Common Stock - (Title of Class of Securities) 00486H105 - (CUSIP Number) June 30, 2024 - (Date of Event Which Requires Filing of this Statement) Check the appropriate box

June 28, 2024 11-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 11-K [X] ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2023 [ ] TRANSITION REPORT PURSUANT TO SECTION

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 11-K [X] ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2023 OR [ ] TRANSITION REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number 001-41446 ADTRAN, Inc. 401(k) RETIREMENT PLA

June 10, 2024 EX-10.5

ADVA Guaranty Agreement, dated as of June 4, 2024 by and between ADVA NA Holdings, Inc., Adtran Networks North America, Inc., Adtran Networks (UK) Limited, in favor of Wells Fargo Bank, National Association (incorporated by reference to exhibit 10.1 to the Company's Form 8-K filed June 10, 2024)

EXHIBIT 10.5 EXECUTION VERSION ADVA GUARANTY AGREEMENT dated as of June 4, 2024, by and among ADVA NA HOLDINGS, INC., ADTRAN NETWORKS NORTH AMERICA INC., and ADTRAN NETWORKS (UK) LIMITED, each as an ADVA Subsidiary Guarantor, in favor of WELLS FARGO BANK, NATIONAL ASSOCIATION, as Administrative Agent Table of Contents Page ARTICLE 1 DEFINED TERMS 1 SECTION 1.1 Definitions 1 SECTION 1.2 Other Defin

June 10, 2024 EX-10.6

ADVA Domestic Collateral Agreement, dated as of June 4, 2024, by and among ADVA NA Holdings, Inc., Adtran Networks North America, Inc., and Adtran Networks SE, in favor of Wells Fargo Bank, National Association (incorporated by reference to exhibit 10.1 to the Company's Form 8-K filed June 10, 2024)

EXHIBIT 10.6 EXECUTION VERSION ADVA DOMESTIC COLLATERAL AGREEMENT dated as of June 4, 2024 by and among ADVA NA HOLDINGS, INC., and ADTRAN NETWORKS NORTH AMERICA INC., each as a U.S. Grantor, and ADTRAN NETWORKS SE., as a Non-U.S. Grantor, in favor of WELLS FARGO BANK, NATIONAL ASSOCIATION, as Administrative Agent Table of Contents Page ARTICLE I DEFINED TERMS 1 SECTION 1.1 Terms Defined in the Un

June 10, 2024 EX-10.1

Fourth Amendment to Credit Agreement, dated as of June 4, 2024, by and among ADTRAN Holdings, Inc., ADTRAN, Inc., Adtran Networks SE, Wells Fargo Bank, National Association, and the lenders party thereto (incorporated by reference to exhibit 10.1 to the Company's Form 8-K filed June 10, 2024)

EXHIBIT 10.1 EXECUTION VERSION FOURTH AMENDMENT TO CREDIT AGREEMENT FOURTH AMENDMENT TO CREDIT AGREEMENT (this “Amendment”), dated as of June 4, 2024, among ADTRAN, INC., a Delaware corporation (the “US Borrower”), ADTRAN NETWORKS SE, a European stock corporation incorporated under the law of the European Union and Germany (“ADVA”), ADTRAN HOLDINGS, INC., a Delaware corporation (“Holdings”), the L

June 10, 2024 8-K

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): June 4, 2024 ADTRAN Holdings, Inc

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): June 4, 2024 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

May 22, 2024 SD

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM SD Specialized Disclosure Report ADTRAN Holdings, Inc. (Exact name of Registrant as specified in its charter)

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM SD Specialized Disclosure Report ADTRAN Holdings, Inc. (Exact name of Registrant as specified in its charter) Delaware (State of Incorporation) 001-41446 (Commission file number) 87-2164282 (I.R.S. Employer Identification Number) 901 Explorer Boulevard, Huntsville, Alabama 35806-2807 (Address of principal executive office

May 22, 2024 EX-1.01

Exhibit 1.01 – Conflict Minerals Report as required by Items 1.01 and 1.02 of this Form.

Exhibit 1.01 Conflict Minerals Report of ADTRAN Holdings, Inc. Company Overview ADTRAN Holdings, Inc. (NASDAQ:ADTN) (“ADTRAN” or the “Company”) is a leading global provider of networking and communications platforms, software, systems and services focused on the broadband access market, serving a diverse domestic and international customer base in multiple countries that includes large, medium and

May 10, 2024 EX-FILING FEES

Filing Fee Table

Exhibit 107 CALCULATION OF FILING FEE TABLE Form S-8 (Form Type) ADTRAN Holdings, Inc.

May 10, 2024 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2024 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-41446 ADTRAN Holdings, Inc.

May 10, 2024 S-8

As filed with the Securities and Exchange Commission on May 10, 2024

As filed with the Securities and Exchange Commission on May 10, 2024 Registration No.

May 10, 2024 S-8

As filed with the Securities and Exchange Commission on May 10, 2024

As filed with the Securities and Exchange Commission on May 10, 2024 Registration No.

May 10, 2024 EX-FILING FEES

Filing Fee Table

Exhibit 107 CALCULATION OF FILING FEE TABLE Form S-8 (Form Type) ADTRAN Holdings, Inc.

May 9, 2024 EX-10.1

ADTRAN Holdings, Inc. 2024 Employee Stock Incentive Plan (incorporated by reference to Exhibit 10.1 to the Company’s Form 8-K filed May 9, 2024)

Exhibit 10.1 ADTRAN HOLDINGS, INC. 2024 employee STOCK INCENTIVE PLAN ARTICLE I PLAN INFORMATION 1.1 General Purpose. The purpose of the Plan is to further the growth and development of the Company by offering employees and key service providers and advisors of the Company and its Subsidiaries the opportunity to own a proprietary interest in the Company. The Company intends that the Plan will prov

May 9, 2024 EX-10.2

ADTRAN Holdings, Inc. 2024 Directors Stock Plan (incorporated by reference to Exhibit 10.2 to the Company’s Form 8-K filed May 9, 2024)

exhibit 10.2 ADTRAN Holdings, INC. 2024 DIRECTORS STOCK PLAN ARTICLE I Purpose 1.1 General Purpose. The purpose of this Plan is to further the growth and development of the Company by encouraging Directors who are not employees of the Company to obtain a proprietary interest in the Company by owning its stock. The Company intends that the Plan will provide such Persons with an added incentive to c

May 9, 2024 8-K

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Financial Statements and Exhibits, Submission of Matters to a Vote of Security Holders

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): May 08, 2024 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

May 7, 2024 8-K

Regulation FD Disclosure, Financial Statements and Exhibits, Results of Operations and Financial Condition

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): May 6, 2024 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

May 7, 2024 EX-99.1

Condensed Consolidated Balance Sheets (In thousands)

EXHIBIT 99.1 ADTRAN Holdings, Inc. reports first quarter 2024 financial results • Q1 revenue above mid-point of guidance; non-GAAP profitability in line with guidance • $53 million sequential improvement in GAAP operating cash flow Huntsville, Alabama, USA. — May 06, 2024 — ADTRAN Holdings, Inc. (NASDAQ: ADTN and FSE: QH9) (“ADTRAN Holdings” or the “Company”) today announced its unaudited financia

May 7, 2024 EX-99.2

Adtran Holdings Investor presentation May 7, 2024

Adtran Holdings Investor presentation May 7, 2024 Cautionary note regarding forward-looking statements Statements contained in this investor presentation which are not historical facts, such as those relating to expectations regarding operating loss, net loss, expenses and margin; ADTRAN Holdings customer win rate and the ongoing expansion of its Mosaic One Platform; the ability of ADTRAN Holdings

May 3, 2024 8-K

Regulation FD Disclosure

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): May 3, 2024 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

May 3, 2024 EX-99.1

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

EXHIBIT 99.1 Ad-hoc notification pursuant to Article 17 of Regulation (EU) No. 596/2014 ADTRAN Holdings, Inc.: Non-cash goodwill impairment for the first quarter 2024 in an estimated amount of $293 million; no impact on non-GAAP results and cash flow for the first quarter 2024 Huntsville, Alabama (United States of America). May 3, 2024 (CT) In connection with the preparation of its consolidated fi

April 17, 2024 8-K

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

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): April 11, 2024 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission Fi

April 4, 2024 DEFA14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A (Rule 14a-101) INFORMATION REQUIRED IN PROXY STATEMENT SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A (Rule 14a-101) INFORMATION REQUIRED IN PROXY STATEMENT SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ☒ Filed by a party other than the Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of

March 27, 2024 DEF 14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A (Rule 14a-101) INFORMATION REQUIRED IN PROXY STATEMENT SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A (Rule 14a-101) INFORMATION REQUIRED IN PROXY STATEMENT SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ☒       Filed by a party other than the Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for

March 27, 2024 DEFA14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A (Rule 14a-101) INFORMATION REQUIRED IN PROXY STATEMENT SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A (Rule 14a-101) INFORMATION REQUIRED IN PROXY STATEMENT SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ☒       Filed by a party other than the Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for

March 25, 2024 SC 13G

ADTN / ADTRAN Holdings, Inc. / Divisar Capital Management LLC Passive Investment

SC 13G 1 adtn13gv3.htm UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No.)* ADTRAN Holdings, Inc. (Name of Issuer) Common Stock, par value $0.01 (Title of Class of Securities) 00486H105 (CUSIP Number) March 15, 2024 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to designat

March 15, 2024 EX-10.5

Third Amendment to Credit Agreement, dated as of March 12, 2024, by and among ADTRAN Holdings, Inc., ADTRAN, Inc., Wells Fargo Bank, National Association, and the lenders party thereto (incorporated by reference to Exhibit 10.5 to the Company’s Form 10-K filed March 15, 2024)

Exhibit 10.5 THIRD AMENDMENT TO CREDIT AGREEMENT THIRD AMENDMENT TO CREDIT AGREEMENT (this “Amendment”), dated as of March 12, 2024, among ADTRAN, INC., a Delaware corporation (the “Borrower”), ADTRAN HOLDINGS, INC., a Delaware corporation (“Holdings”), the Lenders (as defined below) party hereto (constituting the Required Lenders) and WELLS FARGO BANK, NATIONAL ASSOCIATION, as administrative agen

March 15, 2024 8-K

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): March 15, 2024 ADTRAN Holdings, I

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): March 15, 2024 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission Fi

March 15, 2024 EX-99.2

Adtran Holdings Investor presentation March 15, 2024

On February 26, 2024, ADTRAN Holdings, Inc. (the “Company”) issued a press release (the “February 26th Press Release”) announcing its preliminary financial results for the fourth quarter and twelve months ended December 31, 2023 (the “Preliminary Financial Results”). The February 26th Press Release and an accompanying investor presentation were attached as Exhibits 99.1 and 99.2, respectively, to

March 15, 2024 EX-99.3

Supplemental Non-GAAP Financial Measures

EXHIBIT 99.3 Supplemental Non-GAAP Financial Measures ADTRAN Holdings, Inc. (the “Company”) is providing the following tables to present certain non-GAAP information for the reporting periods covered in the Company’s Quarterly Reports on Form 10-Q/A (the “Amended Quarterly Reports”) for the quarters ended March 31, 2023, June 30, 2023 and September 30, 2023, which were filed with the Securities an

March 15, 2024 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K

12liability of warranty UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.

March 15, 2024 10-Q/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q/A Amendment No. 1

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q/A Amendment No.

March 15, 2024 10-Q/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q/A Amendment No. 1

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q/A Amendment No.

March 15, 2024 10-Q/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q/A Amendment No. 2

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q/A Amendment No.

March 15, 2024 EX-21

Subsidiaries of ADTRAN.

Exhibit 21 SUBSIDIARIES OF ADTRAN HOLDINGS, INC. December 31, 2023 Name of Subsidiary Country or State of Incorporation ADTRAN Networks Pty. Ltd Australia ADTRAN Networks Comunicações Ltda. Brazil ADTRAN Canada, Inc. Canada ADTRAN d.o.o. Croatia ADTRAN, Inc. State of Delaware ADTRAN International, Inc. State of Delaware ADTRAN Networks Worldwide, Inc. State of Delaware ADTRAN Networks, LLC State o

March 15, 2024 EX-24

Powers of Attorney.

Exhibit 24 POWER OF ATTORNEY KNOW ALL MEN BY THESE PRESENTS, that each of the undersigned, being a director of ADTRAN Holdings, Inc.

March 15, 2024 EX-99.1

Final Financial Results for the Fourth Quarter and Twelve Months Ended December 31, 2023

EXHIBIT 99.1 Final Financial Results for the Fourth Quarter and Twelve Months Ended December 31, 2023 On February 26, 2024, ADTRAN Holdings, Inc. (the “Company”) issued a press release (the “February 26th Press Release”) announcing its preliminary financial results for the fourth quarter and twelve months ended December 31, 2023 (the “Preliminary Financial Results”). The February 26th Press Releas

February 29, 2024 NT 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 12b-25 NOTIFICATION OF LATE FILING

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 12b-25 NOTIFICATION OF LATE FILING SEC File Number 001-41446 CUSIP Number 00486H105 ☒ Form 10-K ☐ Form 20-F ☐ Form 11-K ☐ Form 10-Q ☐ Form 10-D ☐ Form N-CEN ☐ Form N-CSR For Period Ended: December 31, 2023 ☐ Transition Report on Form 10-K ☐ Transition Report on Form 20-F ☐ Transition Report on Form 11-K ☐ Transition Repor

February 27, 2024 EX-99.1

Condensed Consolidated Balance Sheets (Preliminary, Unaudited) (In thousands)

EXHIBIT 99.1 ADTRAN Holdings, Inc. reports preliminary fourth quarter 2023 financial results • Preliminary Q4 revenue at $225.5 million and at mid-point of guidance • Sequential improvement in preliminary GAAP and non-GAAP operating expenses in Q4, with a 7.6% reduction in GAAP operating expenses and a 15.1% reduction in non-GAAP operating expenses respectively Huntsville, Alabama, USA. — February

February 27, 2024 8-K

Regulation FD Disclosure, Financial Statements and Exhibits, Results of Operations and Financial Condition

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): February 26, 2024 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission

February 27, 2024 EX-99.2

Adtran Holdings Investor presentation February 27, 2024

Adtran Holdings Investor presentation February 27, 2024 Cautionary note regarding forward-looking statements Statements contained in this presentation which are not historical facts, such as those relating to expectations regarding earnings, expenses and margin; the ability of ADTRAN Holdings, Inc.

February 20, 2024 8-K

Non-Reliance on Previously Issued Financial Statements or a Related Audit Report or Completed Interim Review

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): February 20, 2024 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission

February 12, 2024 SC 13G/A

US00486H1059 / ADTRAN, Inc. / VANGUARD GROUP INC - SCHEDULE 13G/A Passive Investment

SC 13G/A 1 tv0014-adtranholdingsinc.htm SCHEDULE 13G/A SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Schedule 13G Under the Securities Exchange Act of 1934 (Amendment No.: 14)* Name of issuer: ADTRAN Holdings Inc Title of Class of Securities: Common Stock CUSIP Number: 00486H105 Date of Event Which Requires Filing of this Statement: January 31, 2024 Check the appropriate box to designa

February 12, 2024 SC 13G

US00486H1059 / ADTRAN, Inc. / WILLIAM BLAIR INVESTMENT MANAGEMENT, LLC - SC 13G Passive Investment

SC 13G 1 tm245766d14sc13g.htm SC 13G UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G* (Rule 13d-102) INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO § 240.13d-1(b), (c), AND (d) AND AMENDMENTS THERETO FILED PURSUANT TO § 240.13d-2 (Amendment No. )* ADTRAN Holdings Inc (Name of Issuer) Common Stock (Title of Class of Securities) 00486H105 (CUSIP Numbe

February 12, 2024 SC 13G/A

US00486H1059 / ADTRAN, Inc. / VANGUARD GROUP INC - SCHEDULE 13G/A Passive Investment

SC 13G/A 1 tv0014-adtranholdingsinc.htm SCHEDULE 13G/A SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Schedule 13G Under the Securities Exchange Act of 1934 (Amendment No.: 13)* Name of issuer: ADTRAN Holdings Inc Title of Class of Securities: Common Stock CUSIP Number: 00486H105 Date of Event Which Requires Filing of this Statement: December 29, 2023 Check the appropriate box to design

January 22, 2024 8-K

Entry into a Material Definitive Agreement, Financial Statements and Exhibits, Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant

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 16, 2024 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission

January 22, 2024 EX-10.1

Second Amendment to Credit Agreement and First Amendment to Collateral Agreement, dated as of January 16, 2024, by and among ADTRAN Holdings, Inc., ADTRAN, Inc., Wells Fargo Bank, National Association, and the lenders party thereto (incorporated by reference to Exhibit 10.1 to the Company’s Form 8-K filed January 22, 2024)

EXHIBIT 10.1 EXECUTION VERSION SECOND AMENDMENT TO CREDIT AGREEMENT AND FIRST AMENDMENT TO COLLATERAL AGREEMENT SECOND AMENDMENT TO CREDIT AGREEMENT AND FIRST AMENDMENT TO COLLATERAL AGREEMENT (this “Amendment”), dated as of January 16, 2024, among ADTRAN, INC., a Delaware corporation (the “Borrower”), ADTRAN HOLDINGS, INC., a Delaware corporation (“Holdings”), the Lenders (as defined below) party

January 22, 2024 SC 13G/A

US00486H1059 / ADTRAN, Inc. / BlackRock Inc. Passive Investment

SC 13G/A 1 us00486h1059012224.txt us00486h1059012224.txt SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No: 2) ADTRAN HOLDINGS, INC. - (Name of Issuer) Common Stock - (Title of Class of Securities) 00486H105 - (CUSIP Number) December 31, 2023 - (Date of Event Which Requires Filing of this Statement) Check the appropriate

December 6, 2023 EX-10.1

Separation Agreement, dated December 4, 2023, by and between the Company and Ronald D. Centis (incorporated by reference to Exhibit 10.1 to the Company’s Form 8-K filed December 6, 2023)

EXHIBIT 10.1 SEPARATION AGREEMENT AND GENERAL RELEASE Ronald Centis (“Employee”) and ADTRAN, Inc. (“Employer”) enter into this Separation Agreement and General Release (“Agreement”): 1. Employee and Employer agree as follows: a. Employee and Employer acknowledge that Employee is currently employed as Senior Vice President, Services with Employer and Employee’s employment with Employer will end as

December 6, 2023 8-K

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Financial Statements and Exhibits

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): December 4, 2023 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission

December 5, 2023 8-K

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): December 1, 2023 ADTRAN Holdings,

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): December 1, 2023 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission

December 5, 2023 EX-10.3

Form of Stock Option Award Agreement under the ADTRAN, Inc. 2020 Employee Stock Incentive Plan (incorporated by reference to Exhibit 10.3 to the Company’s Form 8-K filed December 5, 2023)

EX-10.3 EXHIBIT 10.3 ADTRAN HOLDINGS, INC. AMENDED AND RESTATED 2020 EMPLOYEE STOCK INCENTIVE PLAN EMPLOYEE NONQUALIFIED STOCK OPTION AGREEMENT NONQUALIFIED STOCK OPTION (the “Option”) granted on [ ] (the “Date of Grant”), by ADTRAN Holdings, Inc., a Delaware corporation (the “Corporation”), to [ ] (the “Grantee”). 1. GRANT OF OPTION. The Corporation hereby grants to the Grantee the irrevocable Op

December 5, 2023 EX-10.1

Eighteenth Amendment, dated December 4, 2023, to the Service Agreement by and between Adtran Networks SE and Christoph Glingener (incorporated by reference to Exhibit 10.1 to the Company’s Form 8-K filed December 5, 2023

EX-10.1 EXHIBIT 10.1 Amendment to Officer’s Employment Agreement – Dienstvertragsänderung für Vorstandsmitglied AMENDMENT TO OFFICER`S EMPLOYMENT AGREEMENT DIENSTVERTRAGSÄNDERUNG VORSTANDSMITGLIED Adtran Networks SE, Martinsried/Meiningen - hereinafter the “Company” – - im Folgenden die “Gesellschaft” - represented by the Supervisory Board vertreten durch den Aufsichtsrat and und Mr./Herrn Dr. Chr

December 5, 2023 EX-10.2

Ninth Amendment, dated December 4, 2023, to the Employment Agreement by and between Adtran Networks SE and Ulrich Dopfer (incorporated by reference to Exhibit 10.2 to the Company’s Form 8-K filed December 5, 2023)

EX-10.2 EXHIBIT 10.2 Amendment to Officer’s Employment Agreement – Dienstvertragsänderung für Vorstandsmitglied AMENDMENT TO OFFICER`S EMPLOYMENT DIENSTVERTRAGSÄNDERUNG AGREEMENT VORSTANDSMITGLIED Adtran Networks SE, Martinsried/Meiningen - hereinafter the “Company” – - im Folgenden die “Gesellschaft” - represented by the Supervisory Board vertreten durch den Aufsichtsrat and und Mr./Herrn Ulrich

November 9, 2023 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-41446 ADTRAN Holdings, Inc.

November 7, 2023 EX-99.2

Cautionary note regarding forward-looking statements Statements contained in this presentation which are not historical facts, such as those relating to expectations regarding earnings, expenses and margin; the ability of ADTRAN Holdings, Inc. (“ADTR

Exhibit 99.2 Adtran Holdings November 06, 2023 Investor presentation Cautionary note regarding forward-looking statements Statements contained in this presentation which are not historical facts, such as those relating to expectations regarding earnings, expenses and margin; the ability of ADTRAN Holdings, Inc. (“ADTRAN Holdings”) to reduce expenses in the coming year and the amount thereof throug

November 7, 2023 8-K

Regulation FD Disclosure, Financial Statements and Exhibits, Results of Operations and Financial Condition

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): November 6, 2023 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission

November 7, 2023 EX-99.1

Condensed Consolidated Balance Sheets (In thousands) September 30, 2023 December 31, 2022 Assets Current Assets Cash and cash equivalents $ 116,092 $ 108,644 Short-term investments — 340 Accounts receivable, net 229,333 279,435 Other receivables 24,3

Exhibit 99.1 ADTRAN Holdings, Inc. reports third quarter 2023 financial results and announces business efficiency program • Q3 revenue at $272.3 million with sequential improvement in GAAP and non-GAAP operating expenses • 15% projected reduction in non-GAAP operating expenses in Q4 2023 as compared to Q3 2023 • Targeting positive non-GAAP operating margin for the second quarter 2024 • Expected re

November 7, 2023 EX-99.3

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

Exhibit 99.3 Ad-hoc notification pursuant to Article 17 of Regulation (EU) No. 596/2014 ADTRAN Holdings, Inc.: ADTRAN announces deviation from Q4 2023 consensus and the suspension of dividend payments Huntsville, Alabama (United States of America). November 6, 2023 (CT) Based on the current business development, ADTRAN Holdings, Inc. (“ADTRAN Holdings” or the “Company”) (NASDAQ: ADTN; FSE: QH9) co

October 24, 2023 EX-10.2

ADTRAN Holdings, Inc. Amended and Restated Clawback Policy (incorporated by reference to Exhibit 10.2 to the Company's Form 8-K filed October 24, 2023)

Exhibit 10.2 AMENDED AND RESTATED CLAWBACK POLICY On January 18, 2011, the Board of Directors (the “Board”) of ADTRAN, Inc., the predecessor of ADTRAN Holdings, Inc. (the “Company”), formally approved, upon the recommendation of the Compensation Committee of the Board (the “Committee”), this policy of recoupment for incentive-based compensation in certain circumstances (this “Policy”). This Policy

October 24, 2023 EX-3.1

Second Amended and Restated Bylaws of ADTRAN Holdings, Inc. (incorporated by reference to Exhibit 3.1 to the Company's Form 8-K filed October 24, 2023)

Exhibit 3.1 SECOND AMENDED AND RESTATED BYLAWS OF ADTRAN HOLDINGS, INC. ARTICLE I OFFICES Section 1.1 Location. The address of the registered office of the Corporation in the State of Delaware and the name of the registered agent at such address shall be as specified in the Certificate of Incorporation or, if subsequently changed, as specified in the most recent Certificate of Change filed pursuan

October 24, 2023 8-K

Current Report

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): October 18, 2023 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission

October 24, 2023 EX-10.1

ADTRAN Holdings, Inc. Policy for the Recovery of Erroneously Awarded Incentive Based Compensation (incorporated by reference to Exhibit 10.1 to the Company's Form 8-K filed October 24, 2023)

Exhibit 10.1 ADTRAN HOLDINGS, INC. POLICY FOR THE RECOVERY OF ERRONEOUSLY AWARDED COMPENSATION 1. Purpose. The purpose of this Policy is to describe the circumstances in which Executive Officers will be required to repay, return, or forfeit Erroneously Awarded Compensation to the Company. This Policy shall be interpreted to comply with Rule 10D-1 promulgated under the Securities Exchange Act of 19

October 17, 2023 8-K

Current Report

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): October 16, 2023 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission

October 17, 2023 EX-99.1

ADTRAN Holdings announces preliminary results for the third quarter of 2023

Exhibit 99.1 ADTRAN Holdings announces preliminary results for the third quarter of 2023 Huntsville, Alabama, USA. – October 16, 2023 — ADTRAN Holdings, Inc. (NASDAQ: ADTN and FSE: QH9) (“ADTRAN Holdings” or the “Company”) today announced certain preliminary unaudited financial results for the quarter ended September 30, 2023. All results in this release are approximate due to the preliminary natu

October 17, 2023 EX-99.2

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

Exhibit 99.2 Ad-hoc notification pursuant to Article 17 of Regulation (EU) No. 596/2014 ADTRAN Holdings, Inc.: Preliminary Q3 2023 revenue below guidance but non-GAAP operating margin within guidance Huntsville, Alabama (United States of America). October 16, 2023 (CT) During the preparation of the nine-month report 2023 of ADTRAN Holdings, Inc. (“ADTRAN Holdings” or the “Company”) (NASDAQ: ADTN;

September 29, 2023 8-K

Current Report

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): September 25, 2023 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commissio

August 14, 2023 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-41446 ADTRAN Holdings, Inc.

August 14, 2023 EX-99.1

Corrected Financial Information

EX-99.1 Exhibit 99.1 Corrected Financial Information On August 6, 2023, ADTRAN Holdings, Inc. (the “Company”) issued a press release that reported the Company’s financial results for the fiscal quarter and six months ended June 30, 2023 (the “Earnings Release”). A copy of the Earnings Release was attached as Exhibit 99.1 to the Company’s Current Report on Form 8-K that was furnished to the Securit

August 14, 2023 EX-10.7

First Amendment to Credit Agreement, dated August 9, 2023, by and between ADTRAN Holdings, Inc. and Wells Fargo Bank, National Association (incorporated by reference to Exhibit 10.7 to the Company's Form 10-Q filed August 14, 2023)

Exhibit 10.7 Execution Version FIRST AMENDMENT TO CREDIT AGREEMENT FIRST AMENDMENT TO CREDIT AGREEMENT (this “Amendment”), dated as of August 9, 2023, among, ADTRAN, INC., a Delaware corporation (the “Borrower”), ADTRAN HOLDINGS, INC., a Delaware corporation (“Holdings”), the Subsidiary Guarantors (as defined in the Credit Agreement referred to below) party hereto, the Lenders (as defined below) p

August 14, 2023 10-Q/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q/A Amendment No. 1

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q/A Amendment No.

August 14, 2023 10-K/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K/A Amendment No. 1

12liability of warranty UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.

August 14, 2023 10-Q/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q/A Amendment No. 1

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q/A Amendment No.

August 14, 2023 8-K/A

Financial Statements and Exhibits, Results of Operations and Financial Condition

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K/A Amendment No. 2 CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): August 6, 2023 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 000-41446 87-2164282 (State or Other Jurisdiction of Incorporati

August 10, 2023 8-K/A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K/A Amendment No. 1 CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): August 6, 2023

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 8-K/A Amendment No. 1 CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): August 6, 2023 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporati

August 10, 2023 8-K

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): August 10, 2023 ADTRAN Holdings,

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): August 10, 2023 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission F

August 10, 2023 EX-99.1

ADTRAN Holdings, Inc. Announces Corrected

EX-99.1 EXHIBIT 99.1 ADTRAN Holdings, Inc. Announces Corrected Ex-Dividend Date for Second Quarter Cash Dividend – Payment Amount, Payable Date and Record Date Unchanged HUNTSVILLE, AL — (August 10, 2023) — ADTRAN Holdings, Inc. (NASDAQ: ADTN and FSE: QH9) (“ADTRAN Holdings” or the “Company”) today announced a correction to the ex-dividend date for the cash dividend for the second quarter of 2023,

August 10, 2023 NT 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 12b-25 NOTIFICATION OF LATE FILING

NT 10-Q UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 12b-25 NOTIFICATION OF LATE FILING SEC File Number 000-41446 CUSIP Number 00486H105 (Check One) ☐ Form 10-K ☐ Form 20-F ☐ Form 11-K ☒ Form 10-Q ☐ Form 10-D ☐ Form N-CEN ☐ Form N-CSR For Period Ended: June 30, 2023 ☐ Transition Report on Form 10-K ☐ Transition Report on Form 20-F ☐ Transition Report on Form 11-K ☐

August 7, 2023 EX-99.2

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

EX-99.2 Exhibit 99.2 Ad-hoc notification pursuant to Article 17 of Regulation (EU) No. 596/2014 ADTRAN Holdings, Inc.: Guidance for the third quarter of 2023 expected to deviate from analyst consensus Huntsville, Alabama (United States of America). August 7, 2023 Based on the financial results for the second quarter of 2023 and the first half year of 2023, ADTRAN Holdings, Inc. (“ADTRAN Holdings”

August 7, 2023 8-K

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): August 6, 2023 ADTRAN Holdings, I

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): August 6, 2023 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission Fi

August 7, 2023 EX-99.1

Condensed Consolidated Balance Sheets (In thousands) June 30, December 31, 2023 2022 Assets Current Assets Cash and cash equivalents $ 124,294 $ 108,644 Short-term investments 3,089 340 Accounts receivable, net 239,565 279,435 Other receivables 32,39

EX-99.1 Exhibit 99.1 ADTRAN Holdings, Inc. reports second quarter 2023 results HUNTSVILLE, AL — (August 06, 2023) — ADTRAN Holdings, Inc. (NASDAQ: ADTN and FSE: QH9) (“ADTRAN Holdings” or the “Company”) today announced its financial results for the second quarter of 2023. For the quarter, revenue was $327.4 million, up 90% year-over-year and 1% quarter-over-quarter. Net loss attributable to the Co

June 28, 2023 EX-10.1

Consulting Agreement, dated June 28, 2023, by and between ADTRAN Holdings, Inc. and Michael Foliano (incorporated by reference to Exhibit 10.1 to the Company's Form 8-K filed June 28, 2023)

EX-10.1 Exhibit 10.1 CONSULTING AGREEMENT This Consulting Agreement (this “Agreement”) is made and entered into on June 28, 2023, by and between ADTRAN, Inc., a Delaware corporation (the “Company”), and Michael K. Foliano, a resident of the State of Alabama (“Consultant” and, together with the Company, the “Parties”). Recitals: A. Consultant served as the Chief Financial Officer of ADTRAN Holdings

June 28, 2023 11-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 11-K [X] ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2022 [ ] TRANSITION REPORT PURSUANT TO SECTION

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 11-K [X] ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2022 OR [ ] TRANSITION REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number 001-41446 ADTRAN, Inc. 401(k) RETIREMENT PLA

June 28, 2023 8-K

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): June 28, 2023 ADTRAN Holdings, In

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): June 28, 2023 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission Fil

June 1, 2023 EX-10.1

Eighth Amendment, dated May 26, 2023 including Exhibit 1 thereto, to the Employment Agreement by and between Adtran Networks SE and Ulrich Dopfer (incorporated by reference to Exhibit 10.1 to the Company's Form 8-K filed June 1, 2023)

EX-10.1 Exhibit 10.1 * CERTAIN IDENTIFIED INFORMATION HAS BEEN EXCLUDED FROM THIS EXHIBIT BECAUSE IT IS NOT MATERIAL AND IS THE TYPE OF INFORMATION THE REGISTRANT CUSTOMARILY AND ACTUALLY TREATS AS PRIVATE AND CONFIDENTIAL. REDACTED INFORMATION IS INDICATED BY [***]. Amendment to Officer’s Employment Agreement – Dienstvertragsänderung für Vorstandsmitglied AMENDMENT TO OFFICER`S EMPLOYMENT AGREEME

June 1, 2023 8-K

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): May 26, 2023 ADTRAN Holdings, Inc

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): May 26, 2023 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

June 1, 2023 EX-10.3

Exhibit 1 to the Seventeenth Amendment, dated March 28, 2023 and executed May 31, 2023, to the Employment Agreement by and between Adtran Networks SE and Christoph Glingener (incorporated by reference to Exhibit 10.3 to the Company's Form 8-K filed June 1, 2023).

EX-10.3 Exhibit 10.3 * CERTAIN IDENTIFIED INFORMATION HAS BEEN EXCLUDED FROM THIS EXHIBIT BECAUSE IT IS NOT MATERIAL AND IS THE TYPE OF INFORMATION THE REGISTRANT CUSTOMARILY AND ACTUALLY TREATS AS PRIVATE AND CONFIDENTIAL. REDACTED INFORMATION IS INDICATED BY [***]. EXHIBIT 1 to Amendment to Officer’s Employment Agreement of Christoph Glingener as of March 28, 2023 Christoph Glingener shall recei

May 30, 2023 8-K

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers

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): May 23, 2023 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

May 26, 2023 EX-1.01

Exhibit 1.01 – Conflict Minerals Report as required by Items 1.01 and 1.02 of this Form.

Exhibit 1.01 Conflict Minerals Report of ADTRAN Holdings, Inc. Company Overview ADTRAN Holdings, Inc. (NASDAQ:ADTN) (“ADTRAN” or the “Company”) is a leading global provider of networking and communications platforms and services focused on the broadband access market, serving a diverse domestic and international customer base in multiple countries that includes Tier-1, -2 and -3 service providers,

May 26, 2023 SD

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM SD Specialized Disclosure Report ADTRAN Holdings, Inc. (Exact name of Registrant as specified in its charter)

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM SD Specialized Disclosure Report ADTRAN Holdings, Inc. (Exact name of Registrant as specified in its charter) Delaware (State of Incorporation) 001-41446 (Commission file number) 87-2164282 (I.R.S. Employer Identification Number) 901 Explorer Boulevard, Huntsville, Alabama 35806-2807 (Address of principal executive office

May 15, 2023 8-K

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

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): May 10, 2023 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

May 10, 2023 EX-4

Description of Securities (incorporated by reference to Exhibit 4.1 to the Company's Form 10-Q filed May 10, 2023)

Exhibit 4.1 DESCRIPTION OF THE REGISTRANT’S SECURITIES REGISTERED PURSUANT TO SECTION 12 OF THE SECURITIES EXCHANGE ACT OF 1934 The following description of our securities is intended as a summary only. This description is based the certificate of incorporation, as amended (the “Certificate of Incorporation”) of ADTRAN Holdings, Inc. (the “Company”), the Company’s bylaws, as amended and restated (

May 10, 2023 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2023 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-41446 ADTRAN Holdings, Inc.

May 9, 2023 EX-99

Condensed Consolidated Balance Sheets (In thousands)

EXHIBIT 99.1 ADTRAN Holdings, Inc. Reports Earnings for the First Quarter of 2023 and Declares Quarterly Cash Dividend HUNTSVILLE, Ala. — (May 8, 2023) — ADTRAN Holdings, Inc., (NASDAQ: ADTN and FSE: QH9) (“ADTRAN Holdings” or the “Company”), today announced its financial results for the first quarter of 2023. For the quarter, revenue was $323.9 million. Net loss inclusive of the non-controlling i

May 9, 2023 8-K

Financial Statements and Exhibits, Results of Operations and Financial Condition

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): May 8, 2023 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

May 3, 2023 DEFA14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. ) Filed by the Registrant ☒ Filed by a party other than the Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ☐ Defin

April 11, 2023 8-K

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): April 10, 2023 ADTRAN Holdings, I

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): April 10, 2023 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission Fi

April 11, 2023 EX-99.1

Three Months Ended March 31, 2023

EX-99.1 Exhibit 99.1 ADTRAN Holdings Announces Preliminary Results for the First Quarter of 2023 Huntsville, Alabama, USA. – April 10, 2023 — ADTRAN Holdings, Inc. (NASDAQ: ADTN and FSE: QH9) (“ADTRAN Holdings” or the “Company”) today announced certain preliminary unaudited financial results for the quarter ended March 31, 2023. All figures in this release are approximate due to the preliminary na

April 3, 2023 EX-10.1

First Amendment to the CEO Employment Agreement dated March 29, 2023 (incorporated by reference to Exhibit 10.1 to the Company’s Form 8-K filed April 3, 2023)

EX-10.1 Exhibit 10.1 FIRST AMENDMENT TO EMPLOYMENT AGREEMENT This FIRST AMENDMENT TO EMPLOYMENT AGREEMENT (this “Amendment”) is entered into effective as of March 29, 2023, by and between Thomas R. Stanton, an individual resident of the State of Alabama (the “Executive”), and ADTRAN Holdings, Inc., a Delaware corporation (the “Company”). WHEREAS, the Executive, the Company, and ADTRAN, Inc., a Del

April 3, 2023 8-K

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): March 28, 2023 ADTRAN Holdings, I

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): March 28, 2023 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission Fi

April 3, 2023 EX-10.2

Seventeenth Amendment, dated March 28, 2023, to Employment Agreement by and between ADVA Optical Networking SE and Christoph Glingener (incorporated by reference to Exhibit 10.2 to the Company’s Form 8-K filed April 3, 2023)

EX-10.2 Exhibit 10.2 Amendment to Officer’s Employment Agreement – Dienstvertragsänderung für Vorstandsmitglied AMENDMENT TO OFFICER`S EMPLOYMENT AGREEMENT DIENSTVERTRAGSÄNDERUNG VORSTANDSMITGLIED ADVA Optical Networking SE, Martinsried/Meiningen – hereinafter the “Company” – – im Folgenden die “Gesellschaft” – represented by the Supervisory Board vertreten durch den Aufsichtsrat and und Mr./Herrn

April 3, 2023 EX-10.3

Employment Agreement, dated September 29, 2006 and Amendment Nos. 1-16, by and between ADVA Optical Networking SE and Christoph Glingener (incorporated by reference to Exhibit 10.3 to the Company’s Form 8-K filed April 3, 2023)

EX-10.3 Exhibit 10.3 Officer’s Employment Agreement - Dienstvertrag für Vorstandsmitglieder OFFICER’S EMPLOYMENT AGREEMENT DIENSTVERTRAG für VORSTANDSMITGLIEDER The following Officer’s Employment Agreement is concluded between Folgender Anstellungsvertrag wird geschlossen zwischen ADVA AG Optical Networking, Martinsried/Meiningen - hereinafter the “Company” - - im folgenden die “Gesellschaft” - re

March 30, 2023 8-K

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): March 27, 2023 ADTRAN Holdings, I

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): March 27, 2023 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission Fi

March 30, 2023 EX-10.1

Employment Agreement, dated January 28, 2015, and Amendment Nos. 1-9, by and between ADVA Optical Networking SE and Ulrich Dopfer (incorporated by reference to Exhibit 10.1 to the Company’s Form 8-K filed March 30, 2023).

EX-10.1 2 d446533dex101.htm EX-10.1 Exhibit 10.1 Officer’s Employment Agreement - Dienstvertrag für Vorstandsmitglieder OFFICER’S EMPLOYMENT DIENSTVERTRAG AGREEMENT für VORSTANDSMITGLIEDER The following officer’s Employment Agreement is concluded between Folgender Anstellungsvertrag wird geschlossen zwischen ADVA Optical Networking SE, Martinsried/Meiningen - hereinafter the “Company” - - im folge

March 28, 2023 DEF 14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A (Rule 14a-101) INFORMATION REQUIRED IN PROXY STATEMENT SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A (Rule 14a-101) INFORMATION REQUIRED IN PROXY STATEMENT SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ☒ Filed by a party other than the Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confid

March 28, 2023 DEFA14A

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A (Rule 14a-101) INFORMATION REQUIRED IN PROXY STATEMENT SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

DEFA14A 1 d305204ddefa14a.htm DEFA14A UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A (Rule 14a-101) INFORMATION REQUIRED IN PROXY STATEMENT SCHEDULE 14A INFORMATION Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ☒ Filed by a party other than the Registrant ☐ Check the appropriate box: ☐ Preliminary Prox

March 1, 2023 EX-10

Amended and Restated ADTRAN Holdings, Inc. 2020 Employee Stock Incentive Plan.

Exhibit 10.1(t) adtran HOLDINGS, INC. 2020 EMPLOYEE STOCK INCENTIVE PLAN Originally effective May 13, 2020 Amended and Restated Effective July 8, 2022 ADTRAN HOLDINGS, INC. AMENDED AND RESTATED 2020 employee STOCK INCENTIVE PLAN ARTICLE I PLAN INFORMATION 1.1 Background. ADTRAN, Inc. (the “ADTRAN, Inc.”), predecessor to ADTRAN Holdings, Inc. (the “Company”), initially adopted this equity incentive

March 1, 2023 10-K

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K

12liability of warranty UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.

March 1, 2023 EX-10

Amended and Restated ADTRAN Holdings, Inc. 2020 Directors Stock Plan

Exhibit 10.1(u) ADTRAN HOLDINGS, INC. 2020 DIRECTORS STOCK PLAN Originally effective May 13, 2020 Amended and Restated Effective January 24, 2023 ADTRAN Holdings, INC. AMENDED AND RESTATED 2020 DIRECTORS STOCK PLAN ARTICLE I Purpose 1.1 Background. ADTRAN, Inc. (“ADTRAN, Inc.”), predecessor to ADTRAN Holdings, Inc. (the “Company”), initially adopted this equity incentive plan for the benefit of it

March 1, 2023 EX-10

Form of 2022 Integration Award Agreement for ADTRAN Holdings, Inc.

Exhibit 10.1(ag) ADTRAN HOLDINGS, INC. 2023 integration award AGREEMENT This 2023 Integration Award Agreement (this “Agreement”) sets forth the specified terms of a grant of a special integration award (the “Integration Award”) in connection with the business combination (the “Business Combination”) between ADTRAN Holdings, Inc. (the “Company”) and ADVA Optical Networking SE. Specifically, the app

March 1, 2023 EX-21

Subsidiaries of ADTRAN.

Exhibit 21 SUBSIDIARIES OF ADTRAN HOLDINGS, INC. December 31, 2022 Name of Subsidiary Country or State of Incorporation ADTRAN Networks Pty. Ltd Australia ADTRAN Networks Comunicações Ltda. Brazil ADTRAN Canada, Inc. Canada ADTRAN d.o.o. Croatia ADTRAN International, Inc. State of Delaware ADTRAN Networks Worldwide, Inc. State of Delaware ADTRAN Networks, LLC State of Delaware Bluesocket, Inc. Sta

March 1, 2023 EX-24

Powers of Attorney.

Exhibit 24 POWER OF ATTORNEY KNOW ALL MEN BY THESE PRESENTS, that each of the undersigned, being a director of ADTRAN Holdings, Inc.

February 21, 2023 8-K

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): February 21, 2023 ADTRAN Holdings

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): February 21, 2023 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission

February 21, 2023 EX-99

Condensed Consolidated Balance Sheets (Preliminary, Unaudited) (In thousands)

EXHIBIT 99.1 ADTRAN Holdings, Inc. Reports Preliminary Earnings for the Fourth Quarter of 2022 and Declares Quarterly Cash Dividend HUNTSVILLE, Ala. — (February 20, 2023) — ADTRAN Holdings, Inc., (NASDAQ: ADTN and FSE: QH9) (“ADTRAN Holdings” or the “Company”), today announced preliminary and unaudited financial results for the fourth quarter of 2022. All figures in this release are approximate du

February 9, 2023 SC 13G/A

US00486H1059 / ADTRAN, Inc. / VANGUARD GROUP INC - SCHEDULE 13G/A Passive Investment

SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Schedule 13G Under the Securities Exchange Act of 1934 (Amendment No.: 12)* Name of issuer: ADTRAN Holdings Inc. Title of Class of Securities: Common Stock CUSIP Number: 00486H105 Date of Event Which Requires Filing of this Statement: December 30, 2022 Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

February 8, 2023 8-K

Termination of a Material Definitive Agreement, Financial Statements and Exhibits

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): February 6, 2023 ADTRAN Holdings, Inc. (Exact name of Registrant as Specified in Its Charter) Delaware 001-41446 87-2164282 (State or Other Jurisdiction of Incorporation) (Commission

January 26, 2023 EX-10.2

Form of VICC Award Letter – Quarterly Bonus Program (incorporated by reference to Exhibit 10.2 of the Company’s Form 8-K filed January 26, 2023)

Exhibit 10.2 [Date] Dear [Recipient Name]: I am pleased to inform you that you have been selected to participate in the Adtran Incentive Bonus Plan for Q1 2023. Your target bonus amount is [Percentage]% of your 2023 quarterly base salary. This one-time bonus payment will be calculated as described in the Adtran Variable Incentive Cash Compensation (VICC) Program (Exhibit A). In accordance with the

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