# EDGAR Filing Document

**Accession Number:** 0000926282
**File Stem:** 0001193125-26-127317
**Filing Date:** 2026-3
**Character Count:** 2256
**Document Hash:** cdd7563f3bfc7389384678c1d8073a4d
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-26-127317.hdr.sgml**: 20260327

**ACCESSION NUMBER**: 0001193125-26-127317

**CONFORMED SUBMISSION TYPE**: DEFA14A

**PUBLIC DOCUMENT COUNT**: 11

**FILED AS OF DATE**: 20260327

**DATE AS OF CHANGE**: 20260327

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** ADTRAN Holdings, Inc.
- **CENTRAL INDEX KEY:** 0000926282
- **STANDARD INDUSTRIAL CLASSIFICATION:** TELEPHONE & TELEGRAPH APPARATUS [3661]
- **ORGANIZATION NAME:** 04 Manufacturing
- **EIN:** 872164282
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** DEFA14A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-41446
- **FILM NUMBER:** 26800990

**BUSINESS ADDRESS:**
- **STREET 1:** 901 EXPLORER BLVD
- **CITY:** HUNTSVILLE
- **STATE:** AL
- **ZIP:** 35806
- **BUSINESS PHONE:** 256-963-8220

**MAIL ADDRESS:**
- **STREET 1:** 901 EXPLORER BLVD
- **CITY:** HUNTSVILLE
- **STATE:** AL
- **ZIP:** 35806

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** ADTRAN INC
- **DATE OF NAME CHANGE:** 19940705

?xml version='1.0' encoding='ASCII'? 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 Proxy Statement

☐ **Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))**

☐ Definitive Proxy Statement

☒ Definitive Additional Materials

☐ Soliciting Material under §240.14a-12

---

| |
|:---|
| ADTRAN Holdings, Inc.  |
| **(Name of Registrant as Specified In Its Charter)**  |
| **Not applicable.**<br>**(Name of Person(s) Filing Proxy Statement, if other than the Registrant)** |

---

Payment of Filing Fee (Check all boxes that apply):

☒ No fee required 

☐ Fee paid previously with preliminary materials 

☐ Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11

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