Facebook Inc (FB.O) said on Wednesday that the personal information of up to 87 million users may have been improperly shared with political consultancy Cambridge Analytica.
Most of the 87 million people whose data was shared with Cambridge Analytica, were in the United States, Facebook Chief Technology Officer Mike Schroepfer wrote in a blog post.
Cambridge Analytica worked on U.S. President Donald Trump’s 2016 campaign.
The firm is also believe to have fraudulently influenced elections in many other countries including Nigeria.
Facebook said it was taking steps to restrict the personal data available to third-party app developers.
The world’s largest-social-media company has been hammered by investors and faces anger from users, advertisers and lawmakers after a series of scandals about fake-news stories, election-meddling and privacy.
Last month, Facebook acknowledged that personal information of about millions of users wrongly ended up in the hands of Cambridge Analytica.
Facebook Chief Executive Mark Zuckerberg will testify about the matter next week before the U.S. House Energy and Commerce Committee, the panel said on Wednesday.
Shares in Facebook were down 1.4 per cent on Wednesday to 153.90 dollars .
They are down more than 16 percent since the Cambridge Analytica scandal broke.
The scandal has kicked off investigations by Britain’s Information Commissioner’s Office, the U.S. Federal Trade Commission and by some 37 U.S. state attorneys general.