Katy Kaminski, Chief Research Strategist at the investment firm AlphaSimplex, tells BBC that the narrative in the markets has been shifting.

Inflation was a concern initially, but Kaminski says now it's moving to fears of economic weakness.

She says the question was, is the market ready for a correction because there is economic weakness?

The strategist says that would be fuelled by economic uncertainty, political uncertainty, and high valuations.

Kaminski says people may want to get out of positions they are currently in.

Michelle Fleury
Reporting from New York

One of the economic indicators that triggered the big shift in US stock markets last week was something called the ISM Manufacturing Index.

That’s a survey of what managers in manufacturing companies in the US expect to happen in the coming months.

Parts of that survey looked pretty dismal for the US economy.

Well, any second now, we’ll be getting the OTHER ISM index, the ISM Services Index, which, as its name suggest surveys managers in the services sector (which make up the bigger part of the economy).

It should make for interesting reading for investors

More now from economist Steven Blitz, who has just told us the US is not in a recession.

He says if the Federal Reserve is going to wait for things to be bad, then "it's too late".

He adds that the US is in a position where there are warnings that if the Federal Reserve doesn't start to cut interest rates, and cut a lot soon, "we will be in recession by the end of the year".

Shanaz Musafer
BBC business reporter

Wow, as expected - we're seeing big falls as trading gets under way.

Tech stocks are taking a beating, with the Nasdaq tech-heavy index down more than 6%.

It could be on track for its worst session since early in the Covid-19 pandemic. It also tumbled last week in a "correction" after hitting a record high last month. The S&P 500 and the Dow Jones are also sharply lower.

This is off the back of weaker than expected US jobs data last week, which has led to fears of a slowdown in the world's biggest economy.

"It's not a recession, but the economy is weakening," according to Steven Blitz, Chief US Economist at the economic consultancy TS Lombard.

Blitz is speaking now with Michelle Fleury on Business Today, which you can watch live at the top of this page.

The Dow has dropped by more than 1000 points, that's about 2.7%. The Nasdaq plummeted by 6.3% shortly after opening.

And the S&P 500 fell 4.1%.

Trading has now started for the day on the New York Stock Exchange.

Stick with us as we watch for any significant trends that emerge.

Michelle Fleury
Reporting from New York

Well, we have quite morning coming up.

Join me on the BBC Channel for Business Today: Opening Bell at 09:30 EDT (14:30 BST), live from NYC.

I’ll get all the latest from market players about what is causing all this turmoil.

We’re speaking to Katy Kaminski is Chief Research Strategist at the investment firm AlphaSimplex.

And to Steven Blitz, Chief US Economist at the economic consultancy TS Lombard.

We'll be live streaming the programme at the top of this page.

In the next 15 minutes, the financial markets will open in New York and we'll see if the huge selloff that's been happening in Asian markets this morning is replicated in the US.

In just one day Japan's Topix index lost more than 400 points - 12% of its value - its worst performance since black Monday nearly 40 years ago.

April La Russe is the head of Investment Specialists at Insight Investment, an asset management company.

Speaking to BBC's World at One, she says the weak jobs data from Friday has knocked on to not only Asia, but all different markets.

"There's been a big shift in market expectations about where we are in the economic cycle and if we're actually seeing some slowing and what central banks should be doing about it," she says.

After weak data from US and patchy data from Europe, she says markets began to think interest rates need to come down, faster than the markets were expecting.

Asked if there are concern of this degree of volatility and whether it leaves some companies exposed due to sharp swings in prices, she says it shouldn't for the most part, and while earning numbers haven't been as high as some analysts expected, companies are in good shape despite not growing as fast as previous.

Image source, Getty Images

Billionaire Warren Buffet's moves are closely watched by investors around the world. And his firm Berkshire Hathaway revealed that it had sold about half its stake in US technology giant Apple.

There has been concern that shares in technology companies, such as those focused on artificial intelligence (AI), have been overvalued and are now facing difficulties.

Intel announced major layoffs last weekas well as disappointing financial results, and there is speculation that its rival Nvidia, which makes AI chips, will delay its latest launch.

The US Nasdaq index, which contains a large number of technology firms, hit a record high last month but last week tumbled by around 10% in what is known as a "correction".

The Dow Jones Industrial Average also dropped 1.5% on Friday, and the S&P 500 ended 1.8% lower.

Friday had a sharp fall in US stock prices following a report on weak jobs data, which stoked fears of a sudden downturn in the world's largest economy.

In July, employers added 114,000 jobs, far fewer than expected, while the unemployment rate rose to its highest level in nearly three years.

The figures raised concerns that a long-running jobs boom in the US might be coming to an end.

It also drove speculation about when and by how much the Federal Reserve will cut interest rates.

Stock markets were already worried about high borrowing costs and unsettled by signs that a long-running rally in share prices, fuelled in part by optimism over artificial intelligence (AI), might be running out steam.

Stock markets in Taiwan, South Korea, India, Australia, Hong Kong and Shanghai have all tumbled.

The Japanese index suffered its worst day in 37 years on Monday, raising concerns among investors over the possibility of a US recession.

Japan's Nikkei 225 is down 12.4% or 4,451 points in the biggest fall by points in history.

In London, the FTSE 100 index fell by 2.8% while in Paris the CAC-40 dropped by 2.5% and Frankfurt's DAX slid by 3.2%.

Hello and welcome to our live coverage of global business markets.

Wall Street is expected to open with sharp declines at 09:30 local time (14:30 BST) after global stock markets tumbled today.

European stock markets sank following nosedives in Asia as fears rise that the US economy is slowing down.

It follows a report of weak jobs data in the US on Friday which sparked concerns about the world's largest economy.

We’ll get a fuller picture when the opening bell rings at Wall St – stay with us.