FORT WORTH, Texas — American Airlines shares are down after a first-quarter outlook that was mostly unchanged from January, indicating that investors might have been looking for a more upbeat view.

American said Tuesday that a key measure of revenue per mile will rise between 3 percent and 4 percent over the first quarter of 2017. In January, American said the increase would be 2 percent to 4 percent.

Analysts say the forecast was expected because rivals including United Airlines had recently raised their revenue outlook.

American, the world's biggest airline, also repeated that it expects higher costs partly due to raises for pilots and flight attendants.

In late morning trading, the shares were down $1.54, or 3.1 percent, to $48.28. Other U.S. airline stocks were down by smaller percentages.