Turns out that an Egg McMuffin for lunch hit the spot at McDonald’s.

The fast-food giant’s decision this fall to offer breakfast items all day in the U.S. market is one reason why McDonald’s is ending 2015 on a notable upswing after starting the year in a deep slump.

Under the guidance of Steve Easterbrook, who took over as McDonald’s chief executive in March, the chain’s U.S. comparable-store sales — that is, sales at restaurants open at least one year — are rising again from year-earlier levels for the first time since 2013.

In response, the price of McDonald’s stock has soared about 25 percent since late August to record highs, making it one of the top-performing stocks in the Dow Jones industrial average this year. Shares closed at $118.57 on Thursday.

Besides all-day breakfast, Easterbrook has pushed McDonald’s to streamline its menu; improve the quality of its hamburgers, chicken sandwiches and other foods; slash its bureaucracy; and bolster its digital marketing effort.

Despite McDonald’s enormous market presence and iconic brand identity, “no business or brand has a divine right to succeed,” Easterbrook said at a McDonald’s investor meeting last month.

“The plain fact is we were not executing to our standards,” he said. “We were missing customer expectations in too many places.”