SAN FRANCISCO - Facebook is under intense scrutiny over its handling of users' data after reports that information on 50 million users was improperly obtained by Britain-based political consulting firm Cambridge Analytica which used the data to help US President Donald Trump's presidential campaign profile voters during the 2016 election.
The Federal Trade Commission (FTC) has opened an investigation into whether Facebook violated an agreement with the agency on data privacy, while US and European officials have called for Facebook chief executive Mark Zuckerberg to explain how personal information about tens of millions of users ended up in the hands of Cambridge Analytica, without the permission or knowledge of the vast majority of those affected.
In the latest turn of events, Facebook shareholders sued the world's largest social media network in San Francisco federal court in a class action on Tuesday (March 20), saying they suffered losses after the data privacy violations disclosure.
Facebook's shares tumbled more than 9 per cent this week, losing US$60 billion (S$79 billion) of its stock market value since the scandal broke over the weekend.
The unfolding crisis has sparked fears of increased regulation which would hurt other social media firms, triggering market sell-off of technology stocks like Snap, which fell 2.5 per cent, and Twitter, which fell more than 10 per cent on Tuesday.
Here are the major players in this saga.
The British data analytics firm at the centre of this controversy after two newspapers reported that the company harvested personal data about Facebook users beginning in 2014.
Best known for assisting the 2016 presidential campaign of Donald Trump, Cambridge Analytica received US$15 million in funding from billionaire Republican donor Robert Mercer, who was introduced to the firm by future White House adviser to Trump, Steve Bannon.
Trump's campaign hired the firm in June 2016 and paid it more than US$6.2 million, according to Federal Election Commission records. It is now facing a government search of its London office, questions from US state authorities, and a demand by Facebook that it submit to a forensic audit.
Cambridge Analytica has denied all the media claims and said it deleted the data after learning the information did not adhere to data protection rules.
ALEXANDER NIX: THE MASTERMIND
The 42-year-old impeccably-dressed chief executive of Cambridge Analytica now finds himself at the centre of a data mining scandal that has ensnared social media giant Facebook.
The firm suspended him after British broadcaster Channel 4 aired another undercover video on Tuesday (March 20), in which Nix claims his UK-based political consultancy's online campaign played a decisive role in Trump's 2016 election victory.
In the programme meant to expose the firm's dirty methods, Nix described questionable practices used to influence foreign elections and said his firm did all the research, analytics and targeting of voters for Trump's digital and TV campaigns. He also boasted that he met Trump when he was the Republican presidential candidate "many times."
Nix also acknowledged his company used a self-destructing email server to communicate with clients in order to eliminate evidence of their contact.
ALEKSANDR KOGAN: THE PROFESSOR
Kogan, 32, moved to the United States from Russia as a child and graduated from the University of California at Berkeley in 2008 with a degree in psychology before moving to Hong Kong for his doctorate. He ultimately joined Cambridge University in 2012, where he remains a research associate in the psychology department, a position he has retained since relocating back to the San Francisco Bay area.
His ill-fated detour from the academic track into the darker corners of social media marketing began in 2014 when Cambridge Analytica turned to him for help. The firm was interested in a data project Kogan had worked on at Cambridge University that was based on research into personality traits and social media.
Kogan had created an app called 'thisisyourdigitallife' that offered Facebook users personality predictions, in exchange for accessing their personal data on the social network and more limited information about their friends - including their "likes" - if their privacy settings allowed it.
Only about 270,000 people downloaded the app, but the researchers were able to mine the profiles of tens of millions of people through tools Facebook had at the time that gave third parties access to a wide swathe of information.
After Kogan was implicated in the scandal, Cambridge University said it had no evidence to suggest that Kogan had used university resources or facilities for his GSR work.
CHRISTOPHER WYLIE: THE WHISTLEBLOWER
The 28-year-old Canadian was diagnosed with attention deficit hyperactivity disorder (ADHD) and dyslexia as a child. He left school at 16 without a single qualification.
But at 17, he was working in the office of the leader of the Canadian opposition. At 19, he taught himself to code, and in 2010, at age 20, he went to London to study law at the London School of Economics.
His job title at Cambridge Analytica was research director and Wylie admitted that it was him who came up with the idea of bringing big data and social media to an established military methodology - "information operations" - then turn it on the US electorate.
In 2017, Wylie became the whistleblower who provided the Guardian with a tranche of documents that laid out the secret workings behind Cambridge Analytica.
MARK ZUCKERBERG: FACEBOOK FOUNDER
A Harvard University dropout, Zuckerberg founded Facebook in his dorm room in 2004 at the age of 19. He became the youngest chief executive and chairman of a Fortune 500 company when the social media network went public in May 2012.
With an estimated net worth of US$67.7 billion, the 33-year old has encountered doubters every step of the way since starting Facebook, yet despite that, built it into a juggernaut valued at US$540 billion.
But for a business built on growing friendships, Facebook is making an astonishing number of enemies. With the latest data scandal, it has come to the point where Zuckerberg will have to prove somehow he is not in way over his head.
Zuckerberg broke his silence on Wednesday, admitting Facebook made mistakes. He said "there's more to do, and we need to step up and do it". Analysts say the scandal has raised the prospect of an expansion of privacy protections across the globe.
SOURCES: REUTERS, BLOOMBERG, NYTIMES, FORBES