The Facebook (FB) co-founder is now the fourth-richest person in the world, thanks to his company’s surging stock sending his fortune north of the $50 billion-mark this week, according to Bloomberg. The total moves Zuckerberg past Mexican billionaire Carlos Slim Helu as well as Amazon (AMZN) CEO Jeff Bezos on Bloomberg’s Billionaires Index.

Zuckerberg still trails third-place billionaire Warren Buffett by nearly $10 billion, while Microsoft (MSFT) founder Bill Gates and Spanish fashion industry billionaire Armancio Ortega are the first- and second-richest people in the world, respectively.

Facebook has weathered this year’s global market volatility relatively well, which helps explain Zuckerberg’s rise through the ranks of the billionaire class. Bloomberg notes that Zuckerberg is the only person in the top five of the world’s richest people to see his fortune increase this year. Facebook’s stock is up roughly 8% this year after the company delivered a blockbuster quarterly earnings report last week.

It’s been an eventful few months for Zuckerberg. The Facebook cofounder and his wife welcomed a baby daughter at the end of 2015, at which point they pledged to eventually give away 99% of their company shares. Meanwhile, earlier this week, Facebook passed Exxon Mobil (XOM), the world’s largest publicly-traded oil company, in terms of total market value.