Facebook Inc. co-founder Mark Zuckerberg is poised to leapfrog Warren Buffett to become the world’s third-richest person.

Zuckerberg, more than a half-century younger than the Berkshire Hathaway Inc. chairman, is now worth $81.3 billion, gaining $8.5 billion this year as Facebook shook off a data-privacy crisis that caused its stock to tumble 18 percent. Its rebound from a closing low of $152.22 on March 27 to a record $201.45 at 9:45 a.m. Wednesday in New York narrowed the gap with Buffett to $725 million, according to the Bloomberg Billionaires Index.

The recovery in Facebook shares has rewarded other insiders as well, including Chief Operating Officer Sheryl Sandberg, who’s now worth $1.8 billion, and Chief Technology Officer Michael Schroepfer, whose 0.05 percent holding is valued at $224 million.

Zuckerberg, 34, also trails Amazon.com Inc. founder Jeff Bezos, the world’s richest person with a $143.6 billion fortune through Tuesday, and Microsoft Corp. co-founder Bill Gates, with $92.7 billion. The Bloomberg index ranks the world’s 500 richest people and is updated after the close of each trading day in New York.

Buffett, 87, once the world’s wealthiest person, is sliding in the ranking thanks to his charitable giving, which he kicked off in earnest in 2006. He’s donated about 290 million Berkshire Hathaway Class B shares to charities, most of it to Gates’s foundation. Those shares are now worth more than $50 billion, according to data compiled by Bloomberg. Zuckerberg has pledged to give away 99 percent of his Facebook stock in his lifetime.