Wall Street stock markets started the week in downbeat mood ahead of some important economic data over the next few days, including September jobs numbers, and also the annual meeting of the International Monetary Fund.

A few minutes into trading, the Dow Jones was at 18,237.8 points, down 0.4%. The broad-based S&P 500 shed 0.3% at 2,161.31, while the tech-rich Nasdaq lost 0.2% at 5,302.37. 

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Facebook has announced a "slimmed down" version of its Messenger app for countries where older smartphones and slower net speeds are more common.

The company said Messenger Lite had the "core features" of the full app such as the ability to share text and photos.

The app will compete with Facebook-owned WhatsApp, which the company says is used by more than a billion people.

One analyst said offering a stripped-back service for developing markets would "drive adoption of services".

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The UK's biggest payday lender, Wonga, has admitted that it double-charged 7,000 customers for their loans on Friday.

It says an internal system error resulted in extra payments being taken from bank accounts.

The customers affected have what are known as Flexi loans, which have to be paid off in three instalments over three months.

Wonga has promised that extra costs and charges incurred will be refunded.

The FTSE 100 hit a 16-month high this morning, according to Reuters, after the pound dived on news that the Prime Minister will trigger Brexit negotiations before the end of March.

In early afternoon trading the market was at 6989.44 - up 90.11 points on Friday's close - as investors priced in currency benefits for companies with business outside the UK. 

Among the top performers were InterContinental Hotels which climbed 2.8%, Royal Dutch Shell which was up 2.7% and Bunzl, up 2.6%. 

The pound was trading at €1.14530 against the euro after earlier hitting a three year low.

The chart shows how the pound has dropped in today's trading compared with Friday.

It's the first time sterling has slumped below €1.1450 against the euro in more than three years, Hargreaves Lansdown analyst Chris Saint points out.

The fall was prompted by Theresa May setting a date for the Brexit process and was compounded by speculation the UK could sacrifice access to the EU single market in return for greater border control, he says.

Sainsbury's social media marketing team have responded with aplomb to an internet troll who laid into the supermarket's new vegan cheeses.

In a lengthy tirade on Facebook, an unidentified woman said the coconut-based range should not be labelled as cheese but called "Gary or something" instead. 

"Go enjoy your cheese less life. Don't try and make up a substitute cheese and call it cheese," she added.   

After vegan customers showed their support for the supermarket en masse on Twitter, Sainsbury's joined in the fun - publishing a spoof photo-shopped advert in which it had rebranded the cheese "Gary".

The tweet has been liked more than 2,500 times. 

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Brazil's in the grip of its worst recession in three decades, but that hasn't stopped its share index rising at one of the fastest rates in the world this year.   

The Bovespa Index of Brazil's biggest companies is up 90% as investors' appetite for South America's largest economy returns, according to investor guru Justin Urquhart Stewart. 

He said the share index's outstanding performance goes against warnings last year that investors should avoid emerging economies like Brazil. 

"This year's fashion fad tends to be next year's tank top and vice versa," he told the BBC.

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The Bank of England is to expand its stress tests of major banks next year to account for new threats to the economy.  

According to Bloomberg, external, it will run two tests on the country’s biggest lenders. 

It comes after the Bank's Financial Policy Committee noted that share prices in the sector were around 20% lower than at the start of the year, reflecting “challenges to future profitability”.

In light of Brexit uncertainty, it added: "[Banks will] require a level of resilience to be maintained that was at least as great as that currently planned, which itself exceeded that required by international baseline standards."

With the chancellor's speech over, Mark Broad, a senior BBC economics producer, has totted up one of Philip Hammond's favoured soundbites.

Business editor Simon Jack also spots some reassurance for the UK tech scene towards the end of the chancellor's speech.

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Chancellor Philip Hammond has lent his support to two of the government's initiatives to bolster growth outside of London. 

He says the Treasury will continue to drive the Northern Powerhouse project - offering reassurance to the scheme's biggest cheerleader, George Osborne.

There's also support in Mr Hammond's speech for the so-called Midlands Engine. 

He jokes that the scheme, plus the outgoing John Lewis boss running for West Midlands mayor for the Tories, will mean the region is "never knowingly undersold". 

George Osborne's former chief of staff predicts new chancellor Philip Hammond won't roll out a huge spending package today or in his Autumn Statement next month.

Chancellor Philip Hammond moves on to the efficiency of British business and how it lags France and the US. 

"Productivity should set political pulses racing," he says at the Conservative Party conference.

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Southern Rail has given the rail workers’ union until Thursday to sign a new deal on proposed job changes.

The train operator wants to change the responsibilities of guards, and says no-one will be out of pocket through the move. But the Rail, Maritime and Transport (RMT) union disputes that. 

The union raised the stakes recently when it announced 14 days of strikes starting next week and ending in December. 

But Southern - which was plagued by strikes over the summer - has given conductors until midday on Thursday to accept the changes or face redundancy. 

Seeking support for its plan, Southern urged customers to tweet to the RMT this morning to show how unhappy they were with the strike action - but this resulted in a backlash on social media.      

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Chancellor Philip Hammond says recent data shows the underlying strength of the UK economy, "but there is no room for complacency".

Businesses face uncertainty, and have understandable questions about the process of the negotiations, the deal that will be done, and what it will mean for their firms, he says.

"We are ready to take whatever steps are necessary to protect this economy from turbulence," he says.

Chancellor Philip Hammond is delivering his speech at the Conservative Party conference. 

He says the key message from the referendum was on "control" - that the UK wants to take back sovereignty from the EU.

He goes on to reiterate there will be no second referendum. "No ifs, no buts, we are leaving the European Union," he says to applause in the room.

But the UK did not vote to become poorer. The country needs to protect jobs and living standards, he adds.