Delta Air Lines said a key measure of revenue rose a bigger-than-expected 10 percent in December, and its stock price rose.

Delta had predicted a gain of 7 percent to 9 percent in per-seat revenue. That’s a closely watched revenue measure for airlines because it focuses on the money collected rather than the number of people who flew.

The increase in December revenue was because of the late Thanksgiving, which meant that many travelers started their trips in November but returned home in December. Revenue for November fell compared with a year earlier for the same reason.

Delta also said fuel for the month cost 3 cents less per gallon than it had predicted.