Investors are fleeing from airline and cruise-line stocks as fear grows that the new virus could spread dramatically beyond China.

American Airlines, Delta Air Lines and several cruise companies were among the worst performers in the Standard & Poor’s 500 index on Monday.

In China, where the virus started, airlines are finally scheduling more seats. That’s a hopeful sign that the virus might be hitting a plateau there.

However, an aviation-data firm is warning that Chinese airlines could wind up canceling many of those rescheduled flights.