It's been a rough start to the week for Mark Zuckerberg. The Facebook founder and CEO became $5 billion poorer in a matter of hours on Monday, and his net worth had dropped by nearly $4 billion more by midday on Tuesday.
Like most of the world's richest people, Mark Zuckerberg's net worth is determined largely by the rise and fall of the stock market. In particular, Zuckerberg's wealth is based on the performance of Facebook shares.
Early on Monday, the company's stock was down as much as 8%, as U.K. and U.S. politicians criticized Facebook and Zuckerberg for alleged data breaches that shared millions of users' personal information. The data was reportedly used for political purposes during the 2016 U.S. presidential election season, which culminated in Donald Trump's arrival in the White House.
When the market closed on Monday, Facebook stock was down roughly 7% for the day. And on Tuesday morning, Facebook shares fell another 5.5%.
According to Forbes "World's Billionaires" list, which updates the estimated wealth of billionaires in real time, Mark Zuckerberg's net worth was roughly $66 billion at around noon on Tuesday, compared to just under $75 billion when the stock market closed on Friday. In other words, Mark Zuckerberg has theoretically lost $9 billion in less than two days.
Although the stock market soared in early 2018, investors have gotten spooked more recently by Trump's move to impose tariffs on imported steel and aluminum, and by the departure of Trump's top economic advisor, among other reasons. Facebook and Mark Zuckerberg have had a particularly rough going in 2018. Zuckerberg's net worth already plunged over $3 billion during one week in early March as Facebook shares were sold off.
Facebook stock had since recovered, and as of Friday Zuckerberg's wealth was up $2.5 billion for the year to date, according to the Bloomberg Billionaire Index. Yet as Facebook shares took a beating on Monday and Tuesday, Zuckerberg went into the red for year, with a theoretical drop in net worth of about $6 billion thus far in 2018.
The Facebook founder wasn't the only tech billionaire hit with steep losses on Monday. Shares of Alphabet, the parent company of Google, were down 4%, and the net worths of company founders Larry Page and Sergey Brin had each fallen roughly $1.5 billion, according to Forbes. The world's richest man, Amazon founder and CEO Jeff Bezos, saw his wealth decrease by $2 billion on Monday as Amazon shares fell by nearly 3%.
But whereas Facebook shares have continued to fall on Tuesday, Amazon stock has recovered, up nearly 2% thus far for the day. The net worth of Jeff Bezos is up again as a consequence, increasing nearly $2 billion according to Forbes.
And overall, Jeff Bezos is having a much better 2018 than Mark Zuckerberg in terms of net worth. Whereas Zuckerberg's wealth has been hit with a net decrease, Bezos is up about $30 billion so far this year.