The two founders remain neck and neck on Bloomberg Billionaires Index on Thursday, both worth an estimated $81.6 billion, with Zuckerberg's Facebook fortune rising and Buffett's net worth falling. (The daily ranking of billionaire net worth is updated at the end of the trading day in New York.)
The gap between the two men's net worth was only $29 million as of Wednesday, according to Bloomberg. That day, Facebook shares rose 2.3 percent, landing Zuckerberg an extra $1.7 billion, according to Forbes.
Currently the fourth richest person in the world, Zuckerberg's net worth is the highest it has ever been, according to Bloomberg's tracking, which goes back to 2012 when Facebook went public.
Ninety-eight percent of Zuckerberg's wealth is in Facebook stock, according to an analysis by WealthX. He also owns a house estimated to be worth $9 million in Palo Alto, California, and land in Hawaii estimated to be worth $100 million, as well as liquid assets.
Facebook's stock price was trading up above $200 Thursday as of 1 p.m. EST.
Facebook shares zoomed higher after news on Wednesday that the photo-focused social media platform Instagram, which is owned by Facebook, crossed one billion monthly active users. Instagram also announced it is getting into long-form video. The social media platform's video hub, called IGTV, will host vertical videos as long as 60 minutes. To begin with, IGTV will not have ads, but CEO Kevin Systrom said it is possible that IGTV will have ads in the future.
Facebook's stock price hit a recent low of $157.20 on April 2 in the wake of the news of the Cambridge Analytica privacy scandal. Personal information of 87 million Facebook users was improperly shared as a result of the leak.
Indeed, Buffett launched The Giving Pledge with his billionaire buddy, Microsoft co-founder Bill Gates, in 2010. The pair want to inspire billionaires around the world to give the majority of their wealth to charity.
In 2015, Zuckerberg and his wife Priscilla Chan announced they would give away 99 percent of their Facebook company stock to the Chan Zuckerberg initiative, their namesake charitable organization.
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