Just four years after the worst shock to the economy since the Great Depression, U.S. corporate profits are stronger than ever, CNNMoney reported.

In the third quarter, corporate earnings were $1.75 trillion, up 18.6 percent from a year ago, according to last week’s gross domestic product (GDP) report. That took after-tax profits to their greatest percentage of GDP in history.

But the record profits come at the same time that workers’ wages have fallen to their lowest-ever share of GDP.

“That’s how it works,” said Robert Brusca, economist with FAO Research Inc. She said there is a natural tension between profits and the cost of labor. “If one gets bigger, the other gets smaller.”

Profits accounted for 11.1 percent of the U.S. economy last quarter, compared with an average of 8 percent during the previous economic expansion. They fell as low as 4.6 percent of GDP during the recession. Read more.