Exhibit 99.1 Allison Transmission Announces Third Quarter 2025 Results INDIANAPOLIS, October 29, 2025 – Allison Transmission Holdings Inc. (NYSE: ALSN), today reported third quarter net sales of $693 million, driven by continued growth in the Defense end market. David S. Graziosi, Chair and Chief Executive Officer of Allison Transmission commented, "Throughout 2025, our largest end market, North America On-Highway, has been negatively affected by global macroeconomic factors leading to demand uncertainty an ...