Why is Facebook investigating the data company Cambridge Analytica?

About 270,000 people installed a data-harvesting Facebook app which was portrayed as part of an online personality quiz that participants were paid to take

Following the expose, Elizabeth Denham, Britain's Information Commissioner, told Channel 4 News that she was "shocked" and "deeply concerned". The revelations that have panicked Facebook executives and spooked its investors started at Cambridge Analytica's offices, the brainchild of now 28-year-old co-founder-turned self-proclaimed-whistleblower Christopher Wylie.

"No systems were infiltrated, and no passwords or sensitive pieces of information were stolen or hacked", Facebook said in its official blog post.

Cambridge Analytica rose to prominence for its work on Donald Trump's presidential campaign, and has been accused of having exercised shadowy influence over British voters.

Best known for assisting the 2016 presidential campaign of U.S. President Donald Trump, Cambridge Analytica is now facing a government search of its London office, questions from U.S. state authorities, and a demand by Facebook that it submit to a forensic audit.

In response to the Channel 4 News investigation, Cambridge Analytica said in a statement: "We entirely refute any allegation that Cambridge Analytica or any of its affiliates use entrapment, bribes or so-called "honey-traps" for any goal whatsoever". It said Cambridge Analytica had agreed to the review and that Kogan had given a verbal commitment, while Wylie "thus far has declined". Wylie now claims the company and its behavior research affiliate Strategic Communication Laboratories have direct links to Russian Federation and used the Facebook data to influence the outcome of the U.S. presidential election.

"We do have some concerns", said Ron Bates, portfolio manager on the $131 million 1919 Socially Responsive Balanced Fund, a Facebook shareholder. Facebook has hired forensic auditors from the firm Stroz Friedberg to help. Facebook, like other social media platforms, is a machine for collecting personal data on individuals-which, true, is willingly given away by to Facebook by its users.

For Cambridge Analytica, the Channel 4 News expose is only the latest headache for a firm once championed by conservatives - and boosted by $15 million in funding from Republican mega-donor Robert Mercer, and his daughter, Rebekah.

Facebook's head of information security is leaving over disagreements about how the company polices the spread of disinformation on its platform, the New York Times first reported Monday.

Facebook has denied the data collection was a breach because people knowingly provided their information.

Criticism of Facebook by lawmakers began over the weekend when The New York Times chronicled findings about the data mishandling calling it a "breach" that "underpinned" the analytics firm's "work on President Trump's campaign in 2016".

Both Facebook and the UK Information Commissioner want to find out whether it was properly destroyed, as Mr Wylie claims it was not.

"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", he added. That information was used to create profiles on millions of Americans, which the company then allegedly sold to President Trump's campaign team in 2016. On Monday, Facebook shares fell US$12.53 or 6.77 per cent to US$172.56 on the New York Stock Exchange. He said his ultimate goal is to ensure that the privacy rights of Canadian Facebook users are protected. Cambridge Analytica has said it fully complied with Facebook's terms of service and is working with the social media giant to resolve the matter.

In an interview Monday on NBC's "Today", Wylie said Cambridge Analytica aimed to "explore mental vulnerabilities of people".

The firm denies all the claims and says the documentary was "edited and scripted to grossly represent the nature of those conversations".