JetBlue Airways Corp. (JBLU) Wednesday posted a quarterly loss as high fuel costs and competition squeezed earnings, and the discount airline forecast losses for the coming year, sending its shares down more than 11 percent.

The loss -- JetBlue's first since its 2002 initial public offering -- exceeded Wall Street expectations, but analysts said they were more concerned about the forecast for the first quarter and for the full year.

Helane Becker, an analyst at the Benchmark Company, said she expected the airline's shares to be under pressure this year. "It is the guidance for continued loss, which is obviously very bearish for the stock," she said.

JetBlue, the No. 2 U.S. low-cost carrier, reported a fourth-quarter net loss of $42.4 million, or 25 cents a share, compared with a net profit of $1.5 million, or 1 cent a share, a year earlier.

Excluding special items, the airline lost 19 cents a share, compared with Wall Street expectations for a loss of 16 cents a share, according to Reuters Estimates.

U.S. airlines have been under pressure as high fuel costs and increasing competition -- including from low-cost carriers -- affect profit, and has pushed some companies, including Delta Air Lines Inc. and Northwest Airlines Corp., into bankruptcy.

But Becker said JetBlue's loss outlook was specific to the carrier and did not reflect a trend for low-cost carriers overall. She said that JetBlue was not hedged well enough on fuel and was expected to buy more planes this year, adding to its cost burden.

New York-based JetBlue said operating revenue rose 34 percent to $446 million as the airline added new routes to Boston and other destinations.

The carrier said its aircraft fuel expense increased 89.5 percent to about $152 million, as average fuel costs surged 50.3 percent to $1.87 per gallon in the quarter.

Ray Neidl, an analyst at Calyon Securities, said JetBlue's earnings not only fell short of his expectations, but he had also been expecting the carrier to post a profit for 2006. Neidl rates the stock "neutral."

The airline expects to report a negative operating margin of 3 percent and 5 percent in the first quarter, assuming fuel costs $1.92 per gallon.

For 2006, it forecast an operating margin between 2 percent and 4 percent, based on an assumed aircraft fuel cost of $1.98 per gallon, net of hedges.

It expects to increase capacity by 27 percent to 29 percent in the first quarter, compared with last year.

JetBlue stock was down $1.49 to $11.55 during morning trading on Nasdaq, making it the worst performer in the sector.