The UK, in a shocker, votes to leave the EU; Markets plunge; Prime Minister David Cameron to resign

In a referendum that shocked both sides and roiled global markets, Britain voted to leave the European Union. Rebuked by a stunning turn of events he had vigorously campaigned against, Prime Minister David Cameron announced his intention to step down by October.

The 52% to 48% outcome came after a hard-fought, 10-week campaign and "startled even proponents of a British exit," observed the New York Times. It quoted Labour lawmaker Chuka Umunna as calling this "a seismic moment for our country." German foreign minister Frank-Walter Steinmeier, called the news “truly sobering” and said, “It looks like a sad day for Europe and for Britain.”

Cameron, with the vocal support of President Obama and virtually every world leader, wasted little time acknowledging the personal defeat and told the nation he was not the person to carry out their wishes.

"I think the country requires fresh leadership to take it in this direction," Cameron said in front of 10 Downing Street. "I do not think it would be right for me to be the captain that steers our country to its next destination."

Read David Cameron's full remarks

World markets — which priced in no change in the status quo — reacted with panic. British bank stocks plummeted up to 30%.The pound — which had hit 2016 highs — was down by more than 10%, its lowest level in three decades. Gold — a time-honored safe haven investment — was up 8%, to its highest level in two years. Britain's benchmark FTSE 100 crashed at the open:

In mid-session US trading, the Dow was down 500 points and the S&P was down more than 2.5%.

US pre-market activity, the Dow was indicated to open down more than 400 points, but well off session lows. Nasdaq and the broader market were also way down but off the initial shock.

The next several days may offer a clearer sense of where markets will ultimately land, although the vote may have a longer term effect on the global economy. “That is likely to be only the beginning of a prolonged period of financial uncertainty that will hit economic confidence well beyond Britain,” predicts The Economist’s Matthew Bishop.

What is next for United Kingdom, however, is clear: the nation will have to officially invoke Article 50 of the Treaty on European Union, a duty Cameron said would fall to his successor — the mechanism which triggers a negotiated separation agreement, which the UK would then have two years to execute.

Bookmakers (who got the Brexit outcome wrong) are now making former London Mayor and leading Leave proponent Boris Johnson odds on favorite to be the next PM, Reuters reported. But Eurasia Group's Ian Bremmer says Johnson has an uphill battle: "If Boris Johnson becomes the leader of the Conservative Party, his ability to strike a solid deal with the EU will be extraordinarily limited. He will simultaneously face hostile European leaders and a revolt within his own country."

Highlighting the complexity of the issue is the fact that a solid majority of members of Parliament are in favor of remaining. The BBC reports that 450 of the 650 MPs have already moved "to keep the UK in the single market in any exit negotiations."

For many, the vote hits close to home: there are three million EU citizens living in the UK and two million Britons in the EU. The effect of Brexit on these groups is as yet unclear — although “it is almost certain that non-British citizens who had the right to live and work in the UK would need documentation to prove their rights beyond an exit,” predicts The Guardian. This will no doubt be a major component to the negotiations between the two entities. Cameron said changes in these areas will not happen immediately.

The UK is the first nation to leave the 28-nation group. But it may not be the last: Ian Bremmer handicaps the best guesses.

Here’s what professionals are saying so far about the vote on LinkedIn:

"Strange things happen when advanced economies persist in a new normal of protracted low growth and worsening inequality."

• Mohamed El-Erian, Chief Economic Advisor, Allianz

"The UK will experience its own domestic G-zero, and a period of domestic creative destruction will ensue."

• Ian Bremmer, President at Eurasia Group

"With the Eurozone economy still struggling to return to growth after the financial crash of 2008 and subsequent sovereign debt crisis, Brexit is going to come as a severe blow.”

• Matthew Bishop, Senior Editor, The Economist Group

"If these crashes tell us anything, it's that we have to remember that policy and referenda have real world implications, and pretending they don't exist will not do anything to shield us from their real life impact."

• Kunal Kerai, ProSeed founder and UC Berkeley student

“Brand Britain has a lot of work to do to regain trust post Brexit. The fact most experts predicted a remain result means that many that saw Britain as a solid, predictable identity will realise now that even one of the most traditional brands in the world has the potential to shock and surprise.”

• Thomas Emmerson, Business Owner and Lead Marketing Consultant at Vanguard 86

"Most of the CEOs think it’s pointless to dwell on the decision, to start blaming, to find ways of redressing the decision."

• Steve Tappin, CEO at Xinfu, CEO coach & BBC CEO guru

"Our true priority for the weeks and months ahead must be to ensure that the EU remains inspiring and a desirable project once again, one that is forward-looking and turned toward progress and innovation – the future."

• Charles-Edouard Bouée, CEO at Roland Berger

"Whatever the outcome, it is likely that trading with EU countries will be less straightforward for UK companies than it is now... For smaller companies the administrative burden – and potential trading levies – could become an unsurmountable barrier to trading in Europe."

• Mark Mulligan, Managing Director and Analyst at MIDiA Research

"Untying Britain from the old membership is the easy bit. Harder would be agreeing a new trading relationship, establishing what tariffs and other barriers to entry are permitted, and agreeing on obligations such as free movement. Such a process, EU leaders claim, could take another five years."

• Jez Back, Senior Manager at Deloitte UK

"Those championing Brexit say it will give UK businesses greater agility with which to navigate international markets."

• Bernard Marr, Best-Selling Author and Data Expert

Cover Photo: British Prime Minister David Cameron speaks to the press in front of 10 Downing street in central London on June 24, 2016. Prime Minister David Cameron announced Friday he will resign after Britons voted to leave the European Union despite his campaign to keep it in the bloc. / AFP / ADRIAN DENNIS (Photo credit should read ADRIAN DENNIS/AFP/Getty Images)