It is, if you think about it, ridiculous. To judge by the anguished reports from market commentators, the US financial community was waiting with bated breath on Friday for the non-farm payroll figures.

Was the US heading into recession? Had the Federal Reserve made a grave error by not cutting rates earlier? Might it have to slash them by half a percentage point instead of the usual quarter when it meets later this month?

But when the numbers came through rather softer than expected, they punished the high-tech sector and pushed S&P 500 into the worst week it has had this year.

What’s absurd is that one set of statistics, which will be revised anyway, should matter so much.

Sure, job creation was a bit weaker than expected, but there were 142,000 posts added last month, unemployment fell from 4.3 per cent to 4.2 per cent, and average earnings crept up. 

Add in the revisions to previous data, showing fewer jobs had been created than thought, and all that these numbers do it is confirm what we already knew.

The US economy is still growing but at a slower pace. The Federal Reserve will indeed cut interest rates this month, almost certainly by a quarter of a percentage point, and the idea it has somehow failed the nation is for the birds.

The US economy may or may not dip into recession next year – I think the balance of probability is that it won’t – but a delay in cutting interest rates by a few weeks will make zero difference either way.

It is interesting, however, that the mentality of the markets should be so febrile, and that matters for us on this side of the Atlantic. 

There is a twitchy, awkward, frightened mood in the air. Investors are desperate for reassurance. 

They know shares are still close to record highs, but the S&P 500 index had a nasty dip in July. While it then recovered most of the lost ground, the past few days have been very weak.

They need a flow of positive news to justify the heady levels prices are still at now, and those payroll numbers were not quite solid enough to do the trick.

There is a temptation for shareholders who have made huge profits on their high-tech holdings to cash in some of those gains. 

The big names of the American investment community – Stanley Druckenmiller, George Soros, and most famously Warren Buffett – have reported some chunky sales.

That sets a tone for smaller investors: if people who have a lot more money think it is time to sell, maybe they should do so too.

There is also history. After a big run to record levels, as happened in recent weeks, this would almost always be followed a series of deep dips.

So far we have had one, from mid-July to early August. It makes sense to expect more, and it looks as though we are having dip number two right now. 

These dips are focused on the high-tech giants rather than the mass of corporate America, but because the valuations are so huge, a lot of wealth is being destroyed.

Take Nvidia. It topped $3trillion in valuation. On Friday, it was back around $2.5trillion. That loss of $500billion is equivalent to the market cap of America’s oil company, Exxon Mobil. 

You could say that the wealth was never there in the first place, that the valuation on Nvidia was unreasonably high. But that is small comfort to anyone who bought the shares at the top.

Expect this uncertainty to continue through the autumn until it is clear, one way or the other, whether the US is going to fall into recession. That concern will shape our markets here.

On the one hand, our shares are cheap and global investors are coming to appreciate that.

But as the US market is so important, weak prices there will inevitably clobber us here. It is frustrating, but that is how markets work. 

For the long-term investor that is a fine opportunity to buy on the dips. But we should be aware that the mood of US investors could get ugly if the economy seems to falter, and it would be naïve not to expect some dodgy data in the weeks ahead.