What happened: American Airlines (AAL) stock slumped 7% on Thursday. What's behind the move: The air carrier lowered its 2026 earnings forecast again and reported an 83% increase in fuel costs. What else you need to know: American, United (UAL), and Delta (DAL) have all leaned into premium travel as their main driver of growth. While airlines say strong travel demand and higher fares have helped absorb part of the increased fuel costs, fuel remains their second-largest expense after labor. Click here for in-depth analysis of the latest stock market news and events moving stock pricesRead the latest financial and business news from Yahoo Finance