HUNTSVILLE, Ala.--(BUSINESS WIRE)--ADTRAN Holdings, Inc. (NASDAQ: ADTN and FSE: QH9) (“ADTRAN Holdings” or the “Company”) today announced its preliminary unaudited financial results for the fourth quarter of 2023. All results in this release are approximate due to the preliminary nature of the announcement. Preliminary GAAP gross margin for the quarter was 34.8% and improved by 483 bps year-over-year and 754 bps quarter-over-quarter. Besides lower purchasing and transportation costs, the main driver for ...