The 19-per-cent drop in Facebook shares vaporized US$119-billion of the company's market value in the largest one-day loss in market history.
Investors have been anxious about the continuing brand damage the Cambridge Analytica data hacking scandal is taking on Facebook, a day after it revealed three million European users had stopped using Facebook.
Mark Zuckerberg's loss of $15.8bn is equal to the total wealth of the world's 81st-richest person. If that holds through Thursday's close, he will slide to sixth place from third on the Bloomberg Billionaires Index.
Facebook's shares tumble as growth disappoints
Facebook said mobile made up 91 per cent of ad revenue in the recent period, compared with about 87 per cent a year earlier. Revenue fell a little short of estimates - $13.23 billion, compared to the Thomson Reuters estimate of $13.36 billion.
The revenue guidance from the company was "unprecedented", said Gene Munster, an analyst at Loup Ventures, in a note to investors. Shares fell to as low as $176.79 on Thursday morning.
Shares tumbled as much as 20 per cent in NY on Thursday as sales and user growth disappointed investors.
Michael Connor, whose Open Mic group helps investors push tech companies to address privacy, abuse and other issues, said it's "far too early" to see if Facebook's efforts to improve itself will prove fruitful. Leading up to the new stricter privacy rules, Facebook notified users across Europe of pending changes to its privacy policies. Then came the plunge in after-hours trading, after the company revealed it had 2.23 billion monthly users in its last quarter, up 11 per cent from last year's level, but well short of what industry analysts had been expecting.
Facebook has shown that it can not sail forever forward while facing various storms, including Cambridge Analytica and the Russian government's use of the social media platform to sow divisions amongst Americans during the 2016 presidential campaign. Facebook warned that its operating margins would fall from its current 44 percent to the "mid-30s".
FIFA reveals nominees for 2018 The Best Football Awards
Players, coaches, fans, and media will vote on the award and the final three-man shortlist will be announced in September. The FIFA World Player of the Year award was started in 1991 and it ran until 2009.
Some analysts said Facebook's issues would not be easily resolved.
However, media buyers believe the company will bounce back.
Facebook said it expected revenue gains to slow, as people make use of new options to limit advertising and less profitable overseas markets drive growth. Facebook attributed the weaker outlook to unfavorable currency conditions, investments in new products and bolstered privacy tools that may put the brakes on breakneck revenue growth. But the shedding is still notable because Facebook, until now, has only ever experienced growth in users quarter-to-quarter.
He added that Facebook has "a track record of resetting revenue growth and expense expectations only to turn around and exceed those expectations the following quarter".
'What do we got to pay?' Inside the Trump-Cohen tape
McDougal's story during the campaign in a practice known in the tabloid industry as "catch and kill", A.M.I. protected Mr. Trump from negative publicity that could have harmed his election chances, spending money to do so.