Carlifornia, US - Mark Zuckerberg's net worth has plunged about $5 billion after Facebook shares slumped following the Cambridge Analytica scandal in which data of 50 million users was reportedly misused.
The company's stock plummeted nearly 7 percent on Monday putting Facebook on track for their worst day in four years.
Zuckerberg, who is currently the seventh richest person in the world, holds roughly 400 million shares, or 16 percent, in Facebook.
Following the drop, Zuckerberg is now worth an estimated $69.5 billion, according to Forbes.
His company is facing mounting calls to testify after reports emerged that the firm, which has links to President Donald Trump's campaign, gained inappropriate access to data on 50 million Facebook users.
The reports have prompted a review by the company and expressions of concern by several US lawmakers who are demanding that Zuckerberg be grilled by the Senate Judiciary Committee.
One Wall Street analyst said the reports raised 'systemic problems' with Facebook's business model and a number said it could spur far deeper regulatory scrutiny of the platform.
'We think this episode is another indication of systemic problems at Facebook,' said Brian Wieser, analyst at New York-based brokerage Pivotal Research Group, which already has a 'sell' rating on a stock that rose 60 percent last year.
Wieser argued that regulatory risks for the company would intensify and enhanced use of data in advertising would be at greater risk than before.
He added, however, that it was unlikely to have a meaningful impact on the company's business for now, with advertisers unlikely to 'suddenly change the trajectory of their spending growth on the platform'.
The losses in shares on Monday would be among Facebook's biggest daily fall, including a broader market pullback in February. In January, when Facebook announced changes to its newsfeed, which it said would hit user engagement in the near term, shares fell 4.5 percent in one day.
Facebook announced on Monday that it had hired a digital forensics firm to investigate the handling of data leaked to a consulting firm.
A statement said the forensics firm Stroz Friedberg would 'conduct a comprehensive audit of Cambridge Analytica,' and that the company had agreed to comply and provide access to its servers and systems.
Facebook said University of Cambridge psychologist Aleksandr Kogan, who developed the app used to harvest user data, also agreed to cooperate.
It added that Christopher Wylie, the Canadian data analytics expert who worked with Kogan and who revealed the data leak to media, had declined to cooperate with the audit.(FA)
