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Sterling's value against the dollar crashed by 6 per cent in the early hours before partially recovering.
The Bank of England is investigating the causes .
So far explanations range from a "fat finger" mistake by a trader, to a computer trading algorithm gone wrong, to potential market manipulation to make money.
The flash crash... It was the worst intra-day fall for the UK's currency against the greenback since the night of the 23 June Brexit vote when sterling plummeted by 11 per cent.
It was also the second worst on modern record.
The second biggest daily plunge... Yet the flash crash should not pull our attention away from the much bigger picture of sterling weakness in recent days.
Sterling is now at its lowest level against the dollar since 1985.
The weakest value in 31 years... And Sterling is down almost five percent this week alone, on the back of fears among traders and investors that the UK is heading for a "hard" Brexit, meaning we would leave the single market by 2019.
This sell-off was triggered by Theresa May's speech at the Conservative Party conference on Sunday saying that she would commence the two-year divorce by next March.
The brutal week... And the pound has been easily the worst performing of the G10 group of major currencies versus the dollar this year.
A very bad year... Show all 26 Brexit Concerns Brexit will put British patients at 'back of the queue' for new drugs Brexit will put British patients at the “back of the queue” for vital new drugs, the Government has been warned – forcing them to wait up to two years longer A medicines regulator has raised the alarm over a likely decision to pull out of the European Medicines Agency (EMA), as well as the EU itself. ealth Secretary Jeremy Hunt dropped the bombshell , when he said he expected the UK would quit the EMA – because it is subject to rulings by the European Court of Justice.
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Brexit Concerns London to lose status as 'gateway to Europe' for banks One of Germany’s top banking regulators has warned that London could lose its status as “gateway to Europe” for the banking sector after Britain quits the European trading bloc. Andreas Dombret, who is an executive board member for the Bundesbank—Germany’s central bank—told a private meeting of German businesses and banks earlier this week in Frankfurt that even if banking rules were “equivalent” between the UK and the rest of the EU, that was still “miles away from [Britain having] access to the single market”, the BBC reports.
Jason Hawkes
The number of financial sector professionals in Britain and continental Europe looking for jobs in Ireland rocketed in the months after the UK voted to leave the European Union
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Brexit Concerns Brexit is making FTSE 100 executives richer Pay packages of many FTSE 100 chief executive officers are partly tied to how well share prices are doing rather than the CEO’s performance -- and some stocks are soaring. ritish equities got a boost since the June vote because the likes of Rio Tinto, Smiths Group and WPP generate most sales abroad and earn a fortune when they convert these revenues back into the weakened pound. Sterling’s fall also made UK stocks more affordable for overseas investors.
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Brexit Concerns Theresa May: UK to leave single market Theresa May has said the UK "cannot possibly" remain within the European single market, as staying in it would mean "not leaving the EU at all".
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Lead campaigner Gina Miller and her team outside the High Court
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Raymond McCord holds up his newly issued Irish passport alongside his British passport outside the High Court in Belfast following a judges dismissal of the UK's first legal challenges to Brexit
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SDLP leader Colum Eastwood leaving the High Court in Belfast following a judges dismissal of the UK's first legal challenges to Brexit
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Migrants with luggage walk past a graffiti on a wall as they leave the 'Jungle' migrant camp, as part of a major three-day operation planned to clear the camp in Calais
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Migrants leave messages on their tents in the Jungle migrant camp
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The Adventist Development and Relief Agency (Adra) which distributes approximately 700 meals daily in the northern Paris camp states that it is noticing a spike in new migrant arrivals this week, potentially linked the the Calais 'jungle' camp closure - with around 1000 meals distributed today
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Migrant workers pick apples at Stocks Farm in Suckley, Britain
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Many farmers across the country are voicing concerns that Brexit could be a dangerous step into the unknown for the farming industry
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Bank of England governor Mark Carney who said the long-term outlook for the UK economy is positive, but growth was slowing in the wake of the Brexit vote
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The Dow Jones industrial average closed down over 600 points on the news with markets around the globe pluninging
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Immigration officers deal with each member of the public seeking entry into the United Kingdom but on average, 10 a day are refused entry at this London airport and between 2008 and 2009, 33,100 people were detained at the airport for mainly passport irregularities
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A number of global investment giants have threatened to move their European operations out of London if Brexit proves to have a negative impact on their businesses
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Following the possibility of a Brexit the UK would be released from its renewable energy targets under the EU Renewable Energy Directive and from EU state aid restrictions, potentially giving the government more freedom both in the design and phasing out of renewable energy support regimes
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A woman looking at a chart showing the drop in the pound (Sterling) against the US Dollar in London after Britain voted to leave the EU
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Young protesters outside the Houses of Parliament in Westminster, to protest against the United Kingdom's decision to leave the EU following the referendum
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Applications from Northern Ireland citizens for Irish Passports has soared to a record high after the UK Voted in favour of Leaving the EU
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NFU Vice President Minette Batters with Secretary of State, Andrea Leadsome at the National Farmers Union (NFU) took machinery, produce, farmers and staff to Westminster to encourage Members of Parliament to back British farming, post Brexit
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The latest reports released by the UK Cabinet Office warn that expats would lose a range of specific rights to live, to work and to access pensions, healthcare and public services. The same reports added that UK citizens abroad would not be able to assume that these rights will be guaranteed in the future
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A British resident living in Spain asks questions during an informative Brexit talk by the "Brexpats in Spain" group, about Spanish legal issues to become Spanish citizens, at the town hall in Benalmadena, Spain
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The collapse of Great Britain appears to have been greatly exaggerated given the late summer crowds visiting city museums, hotels, and other important tourist attractions
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The U.K. should maintain European Union regulations covering everything from working hours to chemicals until after the government sets out its plans for Brexit, said British manufacturers anxious to avoid a policy vacuum and safeguard access to their biggest export market
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And there could be worse to come.
Analysts say data on the weight of bets in the currency markets suggests that there is a 7 per cent chance of sterling ultimately sinking so low within the next year that it hits parity with the dollar .
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