Amazon cracks top 5 in Fortune's top 500 largest companies as Walmart keeps top spot

Walmart topped Fortune's list of the United States' 500 largest corporations by revenue for the seventh year in a row, as online rival Amazon cracked the top five for the first time.

The annual list ranked companies by their revenue in the 2018 fiscal year.

"FORTUNE 500 companies represent two-thirds of the U.S. GDP with $13.7 trillion in revenues, $1.1 trillion in profits, $22.6 trillion in market value, and employ 28.7 million people worldwide," the company said in a statement.

The second-largest company was oil giant Exxon Mobil, with Apple moving up one spot to third.

In a shift of corporate wealth westward, California-based FORTUNE 500 companies "generated the most aggregate revenue ($1.6 trillion), earned the most aggregate profits ($256 billion), and are valued the most in market cap ($5.5 trillion)," the statement said.

In fact, five of the six most valuable companies were tech giants, with Microsoft, Apple and Amazon each reaching valuations of $1 trillion in the past year.

Also, for the first time, there were 33 female-led companies on the list - the highest number of women CEOs ever. Last year there were 24 on the list.

Here's the top 10:

1.Walmart2.Exxon Mobil3.Apple4.Berkshire Hathaway5.Amazon.com6.UnitedHealth Group7.McKesson8.CVS Health9.AT&T10.AmerisourceBergen

The Walt Disney Co., the parent company of ABC News, ranked 53rd.

For the complete list, click here.