Shares of American Airlines Group Inc. AAL, -0.93% rallied 1.7% in premarket trade Tuesday, after the air carrier raised the low end of its first-quarter unit revenue outlook. In the company's investor update, it said it now expects total revenue per available seat mile (TRASM) of 3% to 4%, compared with previous guidance of 2% to 4%. The company also affirmed its 2018 adjusted earnings-per-share outlook of $5.50 to $6.50, and its total system capacity guidance of up 2.5% from a year ago. American Airlines is scheduled to report first-quarter results on April 26. The stock has lost 4.3% year to date, while the NYSE Arca Airline Index XAL, -0.67% has slipped 1.7% and the S&P 500 SPX, +0.33% has declined 2.3%.