Our GAAP pretax margin for the fourth quarter was 2.2% and GAAP earnings per share was $0.55. On an adjusted basis, our pretax margin was 3.9% and earnings per share was $0.97, which exceeded our latest guidance by approximately $0.50 at the midpoint driven by revenue and cost improvement across our business as well as lower non-operating expenses. Due to these same out-performance factors, full year adjusted EPS of $4.87 also surpassed the better end of our prior guidance range.
Fourth quarter revenue was stronger than expected across both Alaska and Hawaiian, building on the strength seen in the fall, and exiting the year with momentum driven by sustained leisure demand and an uptick in corporate travel which improved close in demand. With mild winter weather to end the year, we delivered reliable operational performance for our guests throughout the holiday travel period, with higher-than-expected completion rate and load factor. After inflecting positive in August, unit revenues improved nearly 6 points sequentially from 1% in the third quarter to 7% in the fourth quarter. This momentum has continued, with ongoing close-in strength in early Q1 bookings. Combined with a stable industry capacity backdrop, we are encouraged by these early indications for Q1 and a constructive start to 2025.
Unit cost performance in the fourth quarter also exceeded our guidance, up 8.6% as compared to pro forma 2023, as disciplined non-fuel cost performance offset higher performance-based pay accruals and better completion rates drove higher capacity. Throughout 2024, unit costs remained pressured from constrained capacity as a result of aircraft delivery delays, but are expected to improve through 2025 as we normalize resource levels and capacity compared to 2024.
