U.S. budget carrier Southwest Airlines' fourth-quarter profit surpassed Wall Street estimates on Thursday, helped by robust travel demand and improved airfares.

Southwest's results echo sentiments laid out by Delta Air Lines, which reported quarterly results earlier in the month. Delta said demand accelerated throughout the fourth quarter, with a handful of its highest revenue days in history taking place in November and December. The company also expects travel demand to remain strong this year.

Southwest Airlines posted a profit in the fourth quarter as bookings during the holidays were better than expected.