Excluding items, the carrier earned $41 million, or 56 cents a share, in the quarter. Analysts surveyed by Thomson Reuters had estimated 50 cents. Revenue rose 28% to $420 million. Analysts had estimated $421 million.
In the fourth quarter a year earlier, Spirit earned $19.5 million, or 27 cents a share. Including items, net income was $43.2 million or 59 cents a share.
The carrier said its revenue increase was "driven by continued strong demand and our growth in capacity (and) to the negative revenue impact in the fourth quarter 2012 related to Hurricane Sandy." Spirit launched service to 25 new markets in 2013.
In premarket trading on Wednesday, Spirit shares were up $1.19 to $48.85. Cowen & Co. analyst Helane Becker wrote Wednesday morning that she expects Spirit "will outperform its peers today due to better-than-expected 4Q13 earnings results."
During the quarter, Spirit's revenue per available seat mile rose 3% to 11.43 cents, reflecting higher passenger yields and load factors. Average revenue per flight segment grew 7.1% to $132.86, primarily driven by an increase in ticket revenue per flight segment. Adjusted pretax margin was 15.4%, an improvement of 5.7 points from the same period a year earlier.
On the cost side, cost per available seat mile excluding special items and fuel fell 2.5% to 5.78 cents, reflecting better operational performance partially offset by higher depreciation and amortization expenses related to increased heavy maintenance events.