Bloomberg have more details of the growing pressure to make top tech executives face a Capitol Hill grilling:

U.S. Senators Amy Klobuchar, a Democrat from Minnesota, and John Kennedy, a Republican from Louisiana, have called on the chairman of the Judiciary Committee to bring in technology company CEOs, including from Twitter Inc. and Alphabet Inc.’s Google, for public questioning

In a letter Monday to Senator Chuck Grassley, a Republican from Iowa, Klobuchar and Kennedy said they have “serious concern regarding recent reports that data from millions of American was misused in order to influence voters.”

“The lack of oversight on how data is stored and how political advertisements are sold raises concerns about the integrity of American elections as well as privacy rights,” the senators wrote. A hearing with the CEOs would allow the committee to learn “what is being done to protect Americans’ data and limit abuse of the platforms, as well as to assess what measures should be taken before the next elections.”

Global stock markets are now on their worst run since last November, according to Reuters data.

Facebook was obviously one factor behind today’s selloff. But, traders are also worried about a protectionist trade war breaking out. This overshadowed the ‘Brexit breakthrough’ between the UK and Brussels over a transition deal this morning.

Facebook’s decision to hire a data forensic firm to examine the claims against Cambridge Analytica has caused some concern.

Particularly as the UK Information Commissioner is planning to obtain a warrant on Tuesday to search its offices.

New details of Cambridge Analytica’s activities are emerging tonight.

Undercover Channel 4 News reporters have recorded CEO Alexander Nix discussing the tactics it used.

Here’s a flavour:

In a series of meetings with a reporter posing as a representative of a wealthy Sri Lankan family seeking political influence, Cambridge Analytica executives initially denied the company was in the business of using entrapment techniques.

But Nix later detailed the dirty tricks the company would be prepared to pull behind the scenes to help its clients.

When the reporter asked if Cambridge Analytica could offer investigations into the damaging secrets of rivals, Nix said it worked with former spies from Britain and Israel to look for political dirt. He also volunteered that his team were ready to go further than an investigation.

“Oh, we do a lot more than that,” he said over dinner at an exclusive hotel in London. “Deep digging is interesting, but you know equally effective can be just to go and speak to the incumbents and to offer them a deal that’s too good to be true and make sure that that’s video recorded.

Newsflash: Facebook has just released a statement, saying it has hired a forensics firm to investigate the claims against Cambridge Analytica.

The social media giant says that Cambridge academic Aleksandr Kogan, who orchestrated the harvesting of Facebook data, has verbally agreed to take part in the audit. Whistleblower Christopher Wylie has ‘thus far declined’, Facebook says.

The Wall Street selloff is gathering pace.

Facebook’s problems seem to be sparking wider alarm in the markets, with investors also worried about the risk of a trade war (and the prospect of a US interest rate rise on Wednesday)

With just over an hour’s trading to go, the Nasdaq is down almost 3% while the Dow is staring at a 450-point loss (-1.8%).

More than $100bn has been wiped off the value of America’s biggest tech companies today.

Facebook is the worst performer (-7%), shedding around $35bn at pixel time. According to the Financial Times, that is one of the ten biggest one-day losses (in dollar terms) ever suffered by a technology company.

Every member of the Nasdaq is currently in the red; Alphabet/Google is down 3.5%, Amazon are down 2.3%, NVIDIA has lost 4.8%, Apple is off 2% and Microsoft has shed 2.2%.

The revelations about how Cambridge Analytica harvested tens of millions of Facebook profiles is fuelling calls for tighter regulation of the tech sector.

And if that happens, the world’s largest technology firms could find their growth squeezed, making it hard to justify their immense valuations (Facebook is still worth half a trillion dollars, despite today’s share price slide)

Jake Dollarhide of Longbow Asset Management believes the implications could be huge.

He says (via Reuters):

“There’s the thought that the government might try to regulate tech. You open a slippery slope. If you regulate Facebook what’s to say that wouldn’t have a domino effect.

Google, maybe Uber?”

What’s to stop the government for getting its fingers in all these areas. People have thought right now the tech growth rate has no boundaries, no ceiling. Today people are beginning to question that. If it’s the case now, will it still be the case in the future.”

US senator Amy Klobuchar, who represents Minnesota, is calling for top tech executives including Mark Zuckerberg to be called to account:

Facebook’s share price is stubbornly in the red, and on track for its worst day in five years:

The UK government has weighed in on the unfolding Facebook data story.

Theresa May’s spokesman has said the PM backs an investigation by the information commissioner into the use of Facebook data by Cambridge Analytica, adding:

The allegations are clearly very concerning, it’s essential people can have confidence that their personal data can be protected and used in an appropriate way.

More here:

The Facebook controversy means investors are shying away from risk in general, sayd Chris Beauchamp, chief market analyst at IG:

Markets are in full retreat this afternoon, and the drop has been exemplified by a triple-digit decline on the FTSE 100. The index has returned to December 2016 levels, a remarkable change from last when it was riding high above 7200.

Devoid of big macro data, investors have focused on the growing scandal at Facebook and this has resulted in a full-blown flight from risk. Investors have begun to fear that the social media giant has encountered its first real obstacle, and that further investigation will uncover other data breaches. The market has been in love with Facebook for a long time now, but with questions surrounding other tech giants and their use of data, it could be only a matter of time until others of the hitherto untouchable ‘FANG’ stocks find themselves dragged into an official investigation.

Another retailer in trouble, as US jewellery and accessories group Claire’s files for bankruptcy. The company said its international operations were not included but it does plan to cut back on the number of its stores in Europe.

The full story is here:

Meanwhile in the UK, Carpetright shares are down 17.5% and Mothercare has lost 12.5% as investors fret about store closures and future prospects for both chains.

It’s not getting any better for Facebook. It’s shares are now down 7% in the wake of the Cambridge Analytica controversy.

The technology gloom on both sides of the Atlantic, including worries about an EU tax and in the UK the slump in Micro Focus shares, is one of the reasons for the day’s market weakness. On Wall Street the Nasdaq Composite is down 2%, while the Dow Jones Industrial Average has lost 280 points or 1.1%.

Investors are also nervous ahead of this week’s Federal Reserve meeting. A rate rise announcement on Wednesday is almost a done deal, but there is much nervousness about whether there will be three or four increases in total this year.

In Europe, Germany’s Dax is down 1.2% and France’s Cac is 0.89% lower while the FTSE 100 has fallen 1.59%, not helped by a stronger pound after positive noises from the Brexit negotiations. Jasper Lawler, head of research at London Capital Group, said:

A sharp decline in tech stocks, US politcal tension between and a ‘death cross’ on Germany’s benchmark DAX index were all weighing on sentiment. Investors are extra touchy in the lead up to Wednesday’s FOMC meeting and the first press conference from new Fed Chair Jerome Powell.

The death cross, when the 50 day moving average crosses below the two-hundred day moving average, is a technical indication that the price trend for German stocks has turned downwards.

Tech stocks saw some of the biggest declines on the day. Facebook’s monopoly on personal data has put the company under the microscope again. There has been public outcry over the use of personal data harvested from Facebook data by Cambridge Analytica for use in election campaigns. The latest data scandal might well be the straw that breaks the camel’s back for tighter industry regulation. Tighter regulation of how data is collected and used will inevitably curb growth for tech and social media companies that use the data to attract advertisers.

Back with Facebook, and the company could now face regulation, sayis Peter Garnry, head of equity strategy at Saxo Bank:

Facebook shares are down almost 4% as the Cambridge Analytica Files were revealed over the weekend by the Guardian. The files expose a major data scandal that Facebook did little to contain or correct. This scandal will fuel into the Mueller investigation and potentially pave the way for the regulation of Facebook as the social media platform is a national security asset because people’s behaviour can be impacted through the network.

Garney also warns about the impact of the EU Commission considering a technology tax of 3% on revenues:

This is move to make technology companies, that are extensively using transfer pricing to avoid taxes in high tax rate countries, to pay more to society. These are just the first signs that major technology companies will be more regulated in the future. It is key for long-term investors in technology to have this on the radar.

On a day when markets in Europe and the US are heavily in negative territory, Barclays is one exception to the rule.

The bank’s shares are up nearly 4% after it emerged that activist investor Edward Bramson had taken control of a 5% stake through his Sherborne Investors. It owns 1.94% of the bank’s shares directly and the rest of the 5% through derivatives. Russ Mould, AJ Bell investment director, said:

Sherborne has built a formidable reputation for squeezing improved financial and operational performance from the companies in which it invests and Edward Bramson clearly feels that Barclays shares are going cheap, given the prevailing discount to the book, or net asset value. The question now is what the activist investor thinks Barclays should be doing differently and how he intends to get those views across to the bank’s boss, Jes Staley.

The fall in Facebook’s value has also hit founder Mark Zuckerberg’s personal wealth. His stake in the business has fallen by around $4bn in the wake of the Cambridge Analytica controversy.

But don’t worry too much. He is still worth around $71bn, making him the world’s fourth richest person according to the Bloomberg Billionaires Index.

Today’s sell off has wiped some $27bn off Facebook’s value, as investors react to the revelations about its relationship with Cambridge Analytica.

Ding ding. The New York stock market has opened, and stocks are dropping in a broad-based selloff.

The Dow Jones industrial average has shed around 100 points, or 0.4%, while the tech-heavy Nasdaq is down almost 1%.

Adam Leyland of The Grocer reckons the Conviviality crisis began after it floated on the stock market in 2013, and started executing ambitious takeover deal to consolidate the drinks trade.

He point out that the company changed CFOs last autumn, and has also been hit by recent bad weather and the post-festive slump.

Leyland writes:

It seems incredible that a business could unravel as quickly as Conviviality has. But with tighter margins and sales commonplace after Christmas, plus tough trading and the snow to contend with, it’s not inconceivable that an operation can quickly lose control of cashflow.

And you lose it at your peril.

The Grocer: Why has Conviviality spent out on company-owned stores?

Newsflash: The CEO of Conviviality, which owns the Bargain Booze and Wine Rack chains, has resigned.

Diana Hunter has stepped down with immediate effect, the company says, less than a week after the company’s shares were suspended after two profits warnings.

Conviviality is in a pickle. Firstly, it revealed that a spreadsheet error meant profits this year would be £5.2m lower than expected. That was compounded last week when it discovered an unpaid £30m tax bill.

Conviviality, which is also a drinks wholesaler, is urgently seeking fresh funds from investors. Last week, Sky News reported that some were demanding Hunter’s exit in return for their support.

Brexit means colour-coding!

The new draft Brexit deal text has been neatly shaded to show areas where there is full agreement (green), political agreement (yellow) and areas which are still under discussion (white0).

It’s official! Britain and the EU have taken a “decisive step” towards withdrawal agreement, says Michel Barnier in Brussels.

After intensive work, the two sides have jointly published a new version of the draft withdrawal deal for Brexit, says Barnier at his joint press-conference with David Davis.

This includes “complete accord” on citizens right and Britain’s financial settlement.

But.. Barnier also cautions that a step is just a step - a lot of work remains to be done, especially on the Ireland border issue.

So, they’re closer, but they’re not there yet.

The pound is pushing a little higher, now up 0.7% against both the US dollar (to $1.405), and the euro (to €1.147).

Politics Live has full details.

Disappointingly, another 46 Carillion workers have been made redundant today by the Official Receiver.

The receiver was unable to find fresh employment for these staff, following Carillion’s fall into liquidation two months ago. This takes the total laid off to 1,582.

In better news, 71 workers have been successfully transferred to a new supplier, which means 8,592 jobs have been saved - or almost half Carillion’s workers.

That leaves around 7,000 workers who are still working on outsourced public or private sector contracts which haven’t yet been transferred to a new operator, or cancelled.

The surge in the pound is helping to drag Britain’s FTSE 100 down to a two-week low.

Micro Focus is also doing its bit - shares are down a staggering 55% after this morning’s gloomy update.

This has helped wipe 90 points off the Footsie, or 1.2%.

Other European markets are also starting the new week rather, er, weakly, with losses in Frankfurt (-0.9%), Paris (-0.7%), Milan (-0.4%) and Madrid (-0.5%)

Investors are edgy ahead of several big news events this week, including the G20 finance ministers meeting in Buenos Aires (ending tomorrow), and Wednesday’s Federal Reserve meeting which is likely to lead to a hike in US interest rates.

Fed chair Jerome Powell’s first press conference since replacing Janet Yellen will give the markets an insight into his thinking, and the likely pace of future rate hikes.

A frisson of excitement is rippling through the foreign exchange floors, amid rumours of a Brexit breakthough.

Britain’s Brexit secretary David David is meeting with chief EU negotiator Michel Barnier now, ahead of the crunch EU summit later this week.

And there are rumours that the two men will announce that the ‘broad’ terms of a transition deal have been agreed. If so, that would calm fears that Britain would crash over the cliff-edge into a hard Brexit in March 2019.

The pound has gained almost a cent against the US dollar to $1.40, and is up 0.5% against the euro to €1.14 (both the highest levels since February)

Barnier and Davis are due to hold a press conference at around 12.45pm Brussels time (11.45am GMT).

Our Politics Live blog will have all the action (plus the latest on the Skripal poisoning).

Back to GKN.... and Melrose has swiftly rubbished today’s news that America’s Dana will list shares in London if it succeeds in merging with GKN’s auto business.

A Melrose spokeswoman argues that City investors will still lose out, due to London’s listing rules.

‘A secondary UK listing will make little difference to the problems it creates for UK holders with Ohio-headquartered Dana maintaining its primary listing on the New York Stock Exchange.

Without a primary UK listing the shares will remain outside the investment mandate of many UK funds who benchmark their performance against the UK indices. Such a listing does not allow indexation, so UK tracker funds can’t hold the shares. Perhaps more significantly many of the UK listing rules which govern corporate behaviour, such as shareholder approval for significant acquisitions, do not apply to a standard listing.

There will still be a major flowback issue which has implications for the underlying price the shares are offered at. Basically, it’s a fudge which is unattractive to UK shareholders’

In a busy morning for takeover news, UK property group Hammerson is fending off an approach from French mall operator Klépierre.

Klépierre has announced this morning that it approached Hammerson about a possible £5bn offer. If it went through, it would thwart Hammerson’s attempt to merge with rival Intu and create Britain’s biggest property firm.

Hammerson has swiftly rejected Klépierre’s approach as “entirely opportunistic” and without merit, even though the 615p per share offer is around 40% over Hammerson’s value last week.

Hammerson shares have jumped 25% this morning, as traders anticipate a bidding battle for the company - which owns 37 shopping centres and retail parks including Birmingham’s Bullring shopping centre.

More here:

In another development, Melrose has lowered the ‘Acceptance Condition’ of its GKN offer, from 90% to 50% plus one share.

That means it has lowered the bar to a successful takeover.