Bad day on the stock market? Chances are it doesn’t compare to the losses Facebook co-founder and CEO Mark Zuckerberg experienced on Thursday after the social media giant’s shares plunged 19% erasing over $119 billion in market cap in just one day, the most ever for a public company, according to our partners at WSJ Market Data Group. It is also the worst percentage drop for the company ever.

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The losses hit Zuckerberg’s wallet to the tune of about $15 billion through the 387,095,123 Facebook shares (Class A and B shares combined) he owns, according to FactSet.

Before the stock dump, Mark Zuckerberg was the fifth wealthiest American in 2018 – with $71 billion net worth according to the Forbes Billionaires List. Considering Thursday's losses – his net worth slipped down to around $55.9 billion. This would remove Zuckerberg from the top 10 of the list – putting him down to the 11th spot behind Oracle co-founder Larry Ellison.

Ticker Security Last Change Change % FB FACEBOOK INC. 249.53 +0.51 +0.20%

The mayhem selling, on heavier than normal volume, followed Facebook's disclosure that increased spending in security and privacy would hurt profitability in the coming quarters. Zuckerberg said on Wednesday the company “will continue to invest heavily in security and privacy,” adding that the associated cost would likely hurt profitability in upcoming quarters. Expenses will rise by 50% to 60% this year as Facebook invests in data security, new technology and other initiatives, CFO David Wehner said. This after second-quarter results missed analyst estimates on several metrics including revenue, users and advertising.

Facebook has faced scrutiny since reports surfaced that British data firm Cambridge Analytica had improperly accessed the personal data of up to 87 million users. While the company’s shares fell initially in the aftermath of the data scandal, they regrouped. But on Thursday, it seems the social media giant is paying for the scandal, in one fell swoop.

Facebook made $1.74 per share in the second quarter, versus analysts’ consensus estimate for $1.72. Revenue fell short of expectations, coming in at $13.23 billion versus the $13.36 billion analysts polled by Thomson Reuters were expecting.