(CNN) -

Walmart has leapfrogged Royal Dutch Shell as the world's largest company, topping the Fortune magazine Global 500 ranking.

The U.S. retail giant has returned to the top spot with $476 billion revenue, up 1.5% compared to last year, after missing out to Shell for two years.

The Fortune Global 500 ranks world's largest companies based on revenue. Here's what the list reveals:

U.S. keeps top spot -- for now

With 128 companies, the U.S. remains the most represented country, at least "for now," Fortune said.

Four American companies dropped off the list this year, while China gained six new representatives. China now has 95 companies in the top 500.

The top ranks are diverse, with seven countries are represented within the top 10. Three of the companies from China while two are from the U.S. There are also companies from the Netherlands, UK, Switzerland, Germany and Japan.

Chinese newcomers dominate

Seven of the 23 newly-listed Fortune 500 companies are Chinese.

The China Development Bank is the highest-ranking newcomer, coming in at number 122. According to the bank, it supported the government's economic policies with more than $160 billion in loans.

Pacific Construction Group was the highest-ranking private company, leap-frogging into number 166 spot.

Russian sanctions impact limited

Two Russian corporations debuted on the Global 500, bringing the total number of the country's companies on the list to eight.

Russian VTB Bank, the country's second largest banking group, and the power networks company Russian Grids made their first appearance in the Global 500, despite Western sanctions imposed on the country following Russia's seizure of Crimea.

Gazprom, Russia's state-owned energy giant, has improved its standing within the top 20. It has climbed from 21 to 17, despite being at the center of the Ukraine crisis. Gazprom signed a huge gas deal with China in May, securing an estimated $456 billion over the 30-year term.

The gender gap

Judging by the number of women heading the world's largest companies, the gender gap is larger on the global stage than it is in the U.S.

Only 17 of the Global 500 companies have a female CEOs, compared to 24 in the U.S.-only Fortune 500 ranking.

Last year, only 12 women made it into the elite club of Global 500 CEOs.

The climbers

Four companies within the top 20 have jumped four ranks up compared to last year. Russia's Gazprom climbed from 21 to 17. Apple jumped from 19 to 15 despite disappointing sales in 2013.

Meanwhile, billionaire investor Warren Buffett saw his Berkshire Hathaway move from 18 to 14, and French insurance giant Axa jumped from 20 to 16.