LONDON, United Kingdom (AFP) — A rapid descent in the pound against the dollar Friday, referred to as a “flash crash”, set tongues wagging across global trading floors as to what triggered the rare event.

What caused the dive?

After the pound crashed more than six per cent against the US dollar in under 10 minutes during Asian trading hours, various explanations have been given.

A spokesman for the Bank of England said simply that it was “looking into what happened” after sterling crashed also to a 6.5-year low versus the euro.

Traders think that in today’s tech-dominated world, it probably had a lot to do with complex mathematical equations known as algorithms.

Automated trading systems can be set up to keep an eye on news headlines and react to potentially market-moving information.

The Financial Times — among the first to report comments by French President Francois Hollande on Brexit — said the computers may have been reading its website.

“Many algorithmic traders include tracking news websites in their systems. The FT story was first published the same minute as the move lower began,” the paper said.

Market analyst David Cheetham at XTB agreed.

“It seems… plausible that news-scanning algorithmic trading systems began a move which gathered momentum as stop loss orders were triggered on the way down,” he said.

What news was potentially analysed?

The pound fell off a cliff at about 23:10 GMT on Thursday to strike a 31-year low at US$1.1841, before rebounding back above US$1.24.

The euro also hit a 6.5-year-high at 94.15 pence.

Analysts say the move could have been in response to Hollande sending one of the strongest warnings yet that Britain will have to pay a heavy price for leaving the European Union.

“Comments from French President Hollande (surfaced) a minute before the selling began, so it seems far more plausible that news-scanning algorithmic trading systems began a move which gathered momentum,” said XTB analyst David Cheetham.

It comes at the end of a week in which British Prime Minister Theresa May hinted at a “hard” Brexit when announcing that her Conservative government was in favour of Britain leaving the single market, thus ending the free movement of people.

“While the pound has recovered a large majority of its losses, it continues to trade well below yesterday’s levels which just goes to show how pessimistic people are about the UK economy in a week in which people have come to realise that a hard Brexit, or something that resembles it, is not just a possibility but a probability,” Erlam added.

In the late afternoon Friday, the pound was trading 1.9 per cent lower against both the US dollar and the euro, at US$1.2381 and 1.1101 euros, respectively.

What lies ahead for the pound?

Kathleen Brooks, research director at City Index, said markets should be braced for more turbulence on sterling trades.

“Since the pound is being driven by headlines at the moment, last night’s price action could put some people off trading the pound in case it happens again,” she told AFP.

“Theresa May said that Brexit negotiations will take place behind closed doors, only adding to the uncertainty about what our exit from the EU will look like, which could trigger further panic in the sterling market. in the months and years to come. Sterling is definitely not out of the woods yet.”