Transdigm Group is trading 7.1% up at $1,183.73 after-hours on September 24, 2026, versus the regular-session close of $1,105.33; no credible company-specific announcement, earnings release, or filing clearly explains the move. - The latest identifiable catalyst was a September 21 agreement for Extant Aerospace to acquire approximately $240 million of assets. - Broader markets declined, making a macro explanation unlikely.