Southwest Airlines Co. is down 4.63%.
After China said it would open its borders next month, U.S. stock indexes were mixed.
As a deep freeze grips the United States, millions of people are hunkering down to ride out the storm.
The winter storm that has hit much of the US and Canada is still causing flight delays and keeping many holiday travelers off the roads. It has also knocked out power to millions of people, just as temperatures are plummeting.