Facebook’s shares lost 5 per cent of their value overnight in response to claims that the company did not adequately protect its users’ data

Shares in the social media giant were trading at $185.09 at close of business on Friday but immediately slumped to $175.19 when markets reopened on Monday morning – equating to a $27 billion drop in the company’s net worth.  
Reports in the press have claimed that research group Cambridge Analytica harvested personal details from up to 50 million Facebook profiles and then used the information to build a predictive modelling tool to predict voting patterns of the US electorate.
Over the weekend, reports in The Guardian and The Observer shed light on the depth of the data breach.
“We exploited Facebook to harvest millions of people’s profiles. And built models to exploit what we knew about them and target their inner demons. That was the basis the entire company was built on,” Christopher Wylie of Cambridge Analytica, told the Observer.
Facebook is now facing allegations that it did not do enough to ensure the security of its members data. The company is also coming under pressure from politicians in the UK and the US to clarify its role in the affair.
"I will be writing to Mark Zuckerberg asking that either he, or another senior executive from the company, appear to give evidence in front of the Committee as part our inquiry. It is not acceptable that they have previously sent witnesses who seek to avoid asking difficult questions by claiming not to know the answers. This also creates a false reassurance that Facebook’s stated policies are always robust and effectively policed," said the Chair of the UK’s Digital, Culture, Media and Sport Committee, Damian Collins.
"We need to hear from people who can speak about Facebook from a position of authority that requires them to know the truth. The reputation of this company is being damaged by stealth, because of their constant failure to respond with clarity and authority to the questions of genuine public interest that are being directed to them. Someone has to take responsibility for this. It’s time for Mark Zuckerberg to stop hiding behind his Facebook page."