ANKARA

Apple reported its highest profit in its history in its fourth-quarter earnings report late on Tuesday.

Profit rose to $54.3 billion for 2015, a 31 percent increase from the previous year, and a record corporate profit level for the U.S., surpassing the previous high of $45.2 billion earned by Exxon in 2008.

Full-year revenue was at $233.7 billon. Sales of iPhones in China were up 87 percent this year, and enabled Apple to beat analyst forecasts handily with earnings of $1.96 per share.

Speaking to the press after the announcement, Apple CEO Tim Cook said that he was not concerned about an economic slowdown in China.

"We continue to invest heavily there," he said.

But Cook warned that sales could slow from now to the end of the year. Sales of iPads were down by a fifth, the earnings announcement said.

The results announcement forecast that sales from October to December would be between $75.5 billion and $77.5 billion, only about a 1 percent increase from the same period in the previous year.

Apple's results, like those of many other U.S. companies, have been hit by the strong dollar, according to the results announcement. This cuts down on income from sales abroad.