The combined total revenue of Fortune's top 500 companies in 2017 reaches 65% of the U.S. GDP.
"Fortune magazine is out with its annual list of America's top 500 companies. The list has been a measure of the country's most valuable businesses since it first came out in 1955. This year, the combined total revenue of all 500 companies reaches $12.1 trillion, 65 percent of the U.S. GDP."