It will be very tempting for many observers to put the FTSE 100’s aggressive fall today – the biggest in percentage terms since the day after the vote to leave the EU – down to concerns over how the Brexit vote in the Commons will pan out.
But that would be parochial, myopic and wrong.
The 3.15% fall in the Footsie looks bad but it is more or less in line with the other falls in equity markets elsewhere around Europe: the Cac 40 in France fell by 3.3%, the Dax in Germany by 3.5% and the MIB in Italy by 3.5%.
Brexit may be consuming the thoughts of many people in this country right now and especially in Westminster.
For global investors, however, it is way, way down on their list of concerns.
That list, right now, is topped by anxiety over Sino-US relations.
Investors did not take long to realise that the supposed ‘trade deal’ at the G20 between Presidents Trump and Xi was nothing of the sort.
So there were already concerns about the trade war between the US and China resuming once the 90-day ‘cooling off’ period agreed in Buenos Aires is over in the spring.
Those concerns have now been exacerbated by the arrest in Canada, at the request of the US, of the chief financial officer of Chinese telecoms equipment maker Huawei.
The company is a trusted partner of the Chinese government and Beijing will regard this arrest – and America’s request for the extradition of Meng Wanzhou to face charges of alleged sanctions busting – as a hostile act.
It will be seen by China as a ratcheting-up of pressure on its companies by Donald Trump.
To that can be added concerns over growth.
The US economy is likely to grow less rapidly in 2019 than it has done this year while many other developed economies are also showing signs of faltering growth.
Japan, often ignored by many investors but still the world’s third-largest economy, suffered an economic contraction during the third quarter of the year.
So, too, did Germany, the world’s fourth-largest economy and the most important in Europe – although in the latter case the big question is whether the recent contraction is merely down to a series of one-off factors or a harbinger of worse to come.
Nowhere can these concerns over growth be seen more clearly than in the market for US government bonds which, earlier this week, threw up a signal that, in the past, has been a reliable indicator of a possible recession.
That has made some economists wonder whether the US Federal Reserve, already under intense pressure from Mr Trump to rein in its planned interest rate rises, will raise rates during the next year to the extent that it was previously expected to.
That is why the US dollar has sold off today.
And on top of all that can be overlaid the fact that this stock market rally is now rather long in the tooth.
The bull market in US and other equities is now into its 10th year which, by historic standards, is long.
Some kind of correction was inevitable.
Bull runs in equities do not, however, die of old age.
There is usually a trigger for some kind of correction and, in this instance, it is an unappealing cocktail of concerns over Mr Trump’s tariffs, the trade war and slowing US growth.
Following this afternoon’s downward lurch on Wall Street, the S&P500 – the most important of the US stock indices – and the Dow Jones Industrial Average are now showing a loss for the year while the tech-heavy Nasdaq is just about the only major index in the world still showing gains for 2018.
That is all very ironic given that sell-offs in several of the tech stocks have had a major impact on how investors, particularly retail investors, look at the stock market in the US.
Small investors in the US are conditioned to “buy the dips” when stock markets fall aggressively but that does not appear to have happened in recent months.
The FAANG stocks – Facebook, Apple, Amazon, Netflix and Google’s owner Alphabet – were all key factors in the bull run, but they have all been battered this autumn, which appears to have hit wider investor sentiment.
Retail investors have avowedly not been buying the dips.
Today’s sell-off, meanwhile, has been led by financials.
If investors think the Fed is unlikely to raise interest rates as rapidly as was previously expected, that is bad news for the banks, whose profits are usually boosted by a rising interest rate environment.
Mr Trump, who tweeted regularly when the stock market was breaking new records earlier this year, has had very little to say about these recent falls.
However, if he is being honest with himself, he will know he is to blame.
US equities were euphoric earlier this year on the back of his corporate tax cuts.
However, the sugar rush has now worn off and, in the eyes of company executives, good Trump who cut taxes for companies has been replaced by bad Trump, who erects tariffs and introduces other protectionist measures.
What is slightly surprising about all of this is that December is usually one of the best months of the year for stock market investors.
There is still time for a ‘Santa rally’.
But concerns over trade, Mr Trump’s relations with China and over slowing growth in the US and other advanced economies mean it would be unwise to count on one.