Facebook has come under further pressure from politicians, investors, advertisers and users, the day after Chief Executive Mark Zuckerberg admitted the social media network made mistakes in letting 50 million users' data get into the hands of political consultancy Cambridge Analytica.
US lawmakers demanded Zuckerberg personally testify in Washington to explain his company's actions.
Meanwhile, advertisers Mozilla and Commerzbank suspended ads on the service and the hashtag #DeleteFacebook remained popular online, although it was hard to tell how many users are abandoning Facebook.
In light of those concerns, investors continued to sell off Facebook shares, although not at the pace of earlier in the week. They closed on Thursday at $US164.89, down 2.7 per cent. The S&P 500 Index was down 2.5 per cent on the day. Facebook shares closed at $US185.09 on Friday.
The company has lost more than $US50 billion in market value since allegations this week that Cambridge Analytica improperly accessed data to build profiles on American voters and influence the 2016 presidential election.
Five days after the scandal broke, Zuckerberg apologised on Wednesday for mistakes his company made and promised to restrict developers' access to user information as part of a plan to protect privacy.
On Thursday, Facebook executives were still saying sorry.
"We know this is an issue of trust. We know this is a critical moment for our company, for the service we provide," Chief Operating Officer Sheryl Sandberg said in an interview broadcast on CNBC.
Zuckerberg's apology and promises were not enough to ease political pressure on the world's largest social media company.
"It shouldn't be for a company to decide what is the appropriate balance between privacy and innovation and use of data. Those rules should be set by society as a whole and so by parliament," British minister for Digital, Culture, Media and Sport, Matt Hancock, told BBC Radio.
