(Bloomberg) -- Delta Air Lines Inc. reduced its expectations for third-quarter profit on higher fuel prices and larger-than-expected maintenance costs, but it reaffirmed its full-year guidance on earnings. 

Adjusted profit will be $1.85 to $2.05 a share, compared with an earlier outlook for as much as $2.50, Delta said in a regulatory filing Thursday. It maintained its guidance for full-year profit of $6 to $7 per share. 

Delta joined other carriers in cutting profit and margin guidance on a 34% increase in jet fuel prices this quarter. US airline shares slumped the most since July on Wednesday after American Airlines Group Inc. and several discount carriers also said quarterly results would be below initial expectations because of higher costs and, in some cases, sagging domestic demand and fares. 

Delta shares fell 0.2% to $39.46 at 9:46 a.m. in New York trading. Delta has climbed 20% this year through Wednesday, the second-best performance in an S&P index of the five largest US carriers. 

Delta’s operating margin this quarter will be about 13%, compared with its earlier outlook for the mid-teens. Non-fuel unit costs, a gauge of efficiency, will climb as much as 2%, compared to earlier expectations that they would fall as much as 3%.

Revenue for each seat flown a mile will decline as much as 3%, versus prior outlook for a dip of as much as 4%, and Delta said total sales would be in the upper half of its earlier expectation for an increase of as much as 14% from last year.  While citing strong transatlantic travel demand, Delta said domestic trends are “steady.” 

Spirit Airlines Inc. warned Wednesday about steep cuts in ticket prices ahead of Thanksgiving while Frontier Air Group Holdings Inc. cited “significant unexpected change” in bookings and sales below historic patterns. Both are fare discounters that operate primarily in the US.

American cut its adjusted earnings outlook to 20 cents to 30 cents a share, compared with an earlier outlook for as much as 95 cents, and halved its adjusted operating margin outlook to as much as 5%. Southwest Airlines Co. and Alaska Air Group Inc. last week warned that revenue would fall more than originally expected this quarter.

(Updates with opening share moves in fourth paragraph)

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