Facebook shares rebounded after taking a sharp fall on Thursday, a day after a secret trove of documents was leaked.

Shares opened around 2.5 per cent down, wiping an estimated $9.5billion off the company's $379billion value, though they rebounded to recover all of the losses by the end of trading, closing up 1.23 per cent for the day.

The documents showed Facebook 'aggressively' pursued competitors, used its platform to cripple rivals, and leverage developers for advertising money, setting up conflicts with regulators and politicians around the globe.

Stock investment firm Stiefel had downgraded Facebook's shares ahead of markets opening in New York, saying the company has made 'too many adversaries' for its business to thrive.

Facebook shares took a pummeling in early trading, opening 2.5 per cent down and wiping around $9.5billion of the company's value

Facebook will be hoping to avoid another crash after shares in the company fell by $119billion in a day back in July, marking the single largest fall in market history.

Mark Zuckerberg saw $12billion wiped off his value as a result of the plunge.

One key issue is how Facebook took 'aggressive positions' against rivals and denied key competitors such as Vine access to its data, which shut down shortly after.

The EU is aggressively cracking down on tech monopolies and this summer fined Google a record $5billion for breaching its competition laws.

What are the accusations against Facebook? Facebook is facing allegations from all over the world that it has been used to spread 'fake news', interfere with elections, and peddle hate. It is also facing hugely damaging revelations of privacy data breaches among its accounts. Here are some of the controversies it has been embroiled in: 'Fake news' and Russia Facebook has come under the spotlight amid claims that Russian accounts used the platform to spread 'fake news' during the 2016 Brexit referendum. In America, Russians accounts have been accused of using Facebook to harm Hilary Clinton's prospects of being elected over Donald Trump. In the UK, some have claimed that misleading information was used to promote Brexit in the run up to the 2016 referendum. Cambridge Analytica Scandal: The data of around 87 million Facebook users was harvested by the company Cambridge Analytica (CA). It has been claimed CA used the information to assess peoples' personalities and come up with political strategies to sway voters to back Brexit and Donald Trump. Spread of extremism and hate Facebook has been repeatedly criticised for not being quick enough to take extremist content down from its site. Critics have warned that Facebook has become a safe haven for extremists who peddle hate and try to recruit jihadis to kill and maim. Advertisement

Regulators found the search engine abused its market dominance with the Android operating system to strong-arm people into using its Chrome browser and apps.

Google also banned rivals from selling devices that used operating systems based on Android, which the EU said was in breach of its rules.

While the EU has so far been silent on the Facebook leak, regulators are certain to be aware of it and will likely investigate whether the social media giant broke any laws.

The documents also revealed that:

Facebook planned to grant companies access to user data based on how much advertising they bought, and threatened to cut off access for firms paying under a certain amount

Facebook programmed its android app to see users call and text records in which it admitted was a 'pretty high-risk thing to do from a PR perspective'

Mr Zuckerberg said he was 'sceptical' that apps with access Facebook users' data would pass data on, as then happened in the Cambridge Analytica scandal

Facebook used Onavo app it acquired to spy on users' phone usage, apparently without their knowledge, to identify competitors such as Whatsapp to buy out

Politicians digging into the spread of fake news online, led by British MP Damian Collins, who leaked the papers, will now have added reason to go after the company for the way it treated users' data.

In choosing to downgrade Facebook's stock from 'buy' to 'hold', warning investors off increasing their holdings in the company, Stiefel told CNBC: 'Facebook’s management team has created too many adversaries -- politicians/ regulators, tech leaders, consumers, and employees -- to not experience long-term negative ramifications on its business.'

On Wednesday night, former Facebook staff described a 'toxic and hostile' atmosphere at the business.

One former senior employee told Buzzfeed News that workers are desperate for a change of leadership.

'People are hoping for a Sundar or Dara moment,' the worker said referring to Uber's new boss Dara Khosrowshahi and Google's chief Sundar Pichai.

Another said staff fear being scolded by furious bosses who are 'spouting full-blown anti-media rhetoric, saying that the press is ganging up on Facebook.'

Documents showed Facebook used its platform to cripple competitors and leverage developers for advertising money, putting it on a collision-course with regulators

What do the Facebook emails say? 1. Facebook planned to let its android app read users' call records in which it admitted was a 'pretty high-risk thing to do from a PR perspective' Michael LeBeau (Facebook product manager) wrote on 4 February 2015: 'As you know all the growth team is planning on shipping a permissions update on Android at the end of this month. They are going to include the 'read call log' permission... This is a pretty high-risk thing to do from a PR perspective but it appears that the growth team will charge ahead and do it.' 2. Facebook aggressively stopped rivals from accessing its users' data to maintain dominance, causing many apps to fail. CEO Mark Zuckerberg personally approved a decision to block Twitter's app Vine from accessing users' Facebook friends lists. Justin Osofksy (Facebook vice president) wrote on 24 January 2012: 'Twitter launched Vine today which lets you shoot multiple short video segments to make one single, 6-second video... Unless anyone raises objections, we will shut down their friends API access today. We've prepared reactive PR, and I will let Jana know our decision.' CEO Mark Zuckerberg replied: 'Yup, go for it.' 3. Mr Zuckerberg said he was 'sceptical' that apps with access Facebook users' data would pass this data on, as then happened in the Cambridge Analytica scandal in 2016 In a 2012 email to Sam Lessin, the company's former VP of Project Management, Mr Zuckerberg wrote: 'I'm generally skeptical that there is as much data leak strategic risk as you think. I agree there is clear risk on the advertiser side, but I haven't figured out how that connects to the rest of the platform. I think we leak info to developers, but I just can't think if any instances where that data has leaked from developer to developer and caused a real issue for us. Do you have examples of this?' 4. Facebook CEOs planned to provide user data to apps which paid Facebook a certain amount Konstantinos Papamiltidas, Facebook's director of platform partnerships, ordered: 'Communicate to all apps that don't spend that those permission[s] will be revoked. 'Communicate to the rest that they need to spend on NEKO [a platform that Facebook uses to sell advertising] $250k a year to maintain access to the data.' Advertisement

The source revealed: 'People now have burner phones to talk s*** about the company - not even to reporters, just to other employees.'

Politicians from eight world governments investigating the spread of fake news, led by British MP Damian Collins who leaked the papers, will also pile pressure on the company to disclose exactly how it monetises user data.

Mr Zuckerberg was 'empty chaired' by the grand committee last week after sent executive Richard Allan for the grilling instead

The papers showed that Facebook signed deals to give companies such as Netflix and AirBnB special access to user dater and spied on Android users' calls and texts.

Facebook strongly denied ever selling user data and insisted it only granted these companies 'short term extensions' to preserve user experience.

Amid the fallout, Zuckerberg was forced to defend himself on Wednesday night, saying in a lengthy Facebook post that the company 'never sold anyone's data'.

Where do the Six4Three Facebook papers come from and why is Mr Collins allowed to publish them? The documents seized by Collins and his committee stem from a court case being heard in California between app developer Six4Three and Facebook. Ted Kramer, who owns the developer, launched a suit against Facebook after the tech company restricted to data that one of his apps - Pinkini - could access. The app was designed to identify bikini photos among albums posted by friends on Facebook, and the restrictions effectively killed it. As part of the lawsuit, Kramer accuses Facebook of encouraging developers to build apps based around access to data that it then withdrew. He also alleges that Zuckerberg sold expensive ads to developers in return for long-term access to the data. This form of access was later exploited by Cambridge Analytica in an attempt to affect elections. As part of his case, Kramer got his hands on documents - said to include confidential emails between senior executives, and correspondence with Zuckerberg - apparently showing they knew about issues around the privacy of user data. Facebook fought for months to keep the documents secret, and was ultimately vindicated when a California judge ruled in its favor. But now Collins has published the documents because he is outside of US jurisdiction and protected in his role as a minister heading up an investigation. Advertisement

He also denied allegations by Collins that changes Facebook made to its platform in 2015 were designed to extract money from developers in return for access to data.

He wrote: 'We've focused on preventing abusive apps for years, and that was the main purpose of this major platform change starting in 2014.

'In fact, this was the change required to prevent the situation with Cambridge Analytica.

'While we made this change several years ago, if we had only done it a year sooner we could have prevented that situation completely.'

The leak relates to a court case between Facebook, an app developer called Six4Three and its app Pinkini, which allowed users to find bikini photos among images uploaded by their friends.

The app was effectively killed when Facebook updated its privacy settings in 2015, and the company is now suing the social media giant.

As part of the legal proceedings, Six4Three was handed a trove of documents from Facebook related to its case, but was told to keep them private.

They were seized by Collins using an obscure parliamentary rule as a Six4Three executive was passing through London in November.

Reacting to the documents being published, a Facebook spokesman said: 'As we've said many times, the documents Six4Three gathered for their baseless case are only part of the story and are presented in a way that is very misleading without additional context.

'We stand by the platform changes we made in 2015 to stop a person from sharing their friends' data with developers.

'Like any business, we had many of internal conversations about the various ways we could build a sustainable business model for our platform.

'But the facts are clear: we've never sold people's data.'

Mr Zuckerberg was 'empty chaired' by the grand committee last week after sent executive Richard Allan for the grilling instead.

Facebook had demanded the Six4Three papers published today be handed back without being opened by MPs or published.

Six4Three managing director Ted Kramer gave the documents to British authorities after being warned he could be banned from leaving the UK if he refused.