Airline stocks are falling as American Airlines says fourth-quarter revenue and full-year profit will be lighter than expected. American’s stock fell 10.9 percent before partially recovering.

American said Thursday that revenue for each seat flown one mile, a measure of pricing power, will rise about 1.5 percent over the previous fourth quarter. That’s about 1 percentage point less than American had been forecasting.

Added to recent comments by Delta, American’s report raises concern among investors that airlines are discounting too many seats because of cheaper fuel.

American is cutting its estimate of 2018 earnings per share to between $4.40 and $4.60, down from its earlier forecast of $4.50 to $5 per share.

In late-morning trading, shares of American Airlines Group Inc. were down $2.72, or 8.1 percent, to $30.70.