0000926282 2026-07-21 2026-07-21 false 0000926282 8-K 2026-07-21 ADTRAN Holdings, Inc. DE 001-41446 87-2164282 901 Explorer Boulevard Huntsville AL 35806-2807 (256) 963-8000 Not Applicable false false false false Common Stock, Par Value $0.01 per share ADTN NASDAQ false