[DALLAS] Delta Air Lines led shares of US carriers higher after posting fourth-quarter profit that topped analysts' estimates and forecasting an operating margin of as much as 8 per cent in this year's initial three months.

Delta, adjusted for its 2008 merger with Northwest Airlines Corp, last had a first-quarter operating margin at that level in 1998, according to Jamie Baker, a JPMorgan Chase & Co analyst.

Airlines are benefiting from lower fuel prices, constraints on capacity growth, controls on operating costs and demand that's keeping planes full, said Ray Neidl of Nexa Capital Partners, an aerospace and transportation consulting firm. Delta was the first major US carrier to report fourth-quarter results.