American Airlines (AAL) stock tumbled 5.39% in Sunday's trading session following a downgrade from Jefferies analyst Sheila Kahyaoglu. The analyst lowered her rating on the airline from Buy to Hold, triggering a significant sell-off in the company's shares.

The downgrade comes as a blow to American Airlines, which has been working to recover from the challenges faced by the airline industry in recent years. While the specific reasons for the downgrade were not fully detailed in the available information, it's likely that Kahyaoglu's decision was based on a reassessment of the company's growth prospects or concerns about its financial performance.

This downgrade may have broader implications for the airline sector, potentially signaling concerns about the industry's recovery trajectory or specific challenges facing legacy carriers. Investors will be closely watching for any further analyst actions or company updates that could provide more insight into American Airlines' outlook and the overall health of the airline industry.