Stock markets have been up and down like Santa in the world's chimneys this Christmas.
After taking a record unfestive pummelling on 24 December, American shares experienced a record oneday gain on Boxing Day. It's a fitting way to end a year that has been characterised by an unusual level of financial volatility.
The MSCI World Index covers most of the developed world's largest listed companies. It raced up in January to a record high. But since then the index has shed around a fifth of that value.
And consider some of the constituents of such indexes. Apple crossed the $1 trillion (£790bn) valuation threshold in August, becoming the first listed company ever to do so. But four months on and the iPhonemaker is worth "just" $740bn. On 26 July Facebook's shares dropped by 20 per cent. That translated into a paper loss of $120bn - the worst day of value destruction suffered by a single company in US corporate history.
The global oil price has bounced around wildly too this year. In October it hit a four-year high of $86 a barrel, prompting concerns about a potential surge of global inflation. But now, within a few months, the black stuff is back down to $54 a barrel.
Sterling peaked at $1.43 in April, up from $1.34 in January. Now the pound languishes at a measly $1.26, beaten down by fears of a no-deal Brexit.
An honorary mention is due to bitcoin. The original cryptocurrency shot up at the start of the year to $17,500. Now one unit trades for only $3,600.
Why does this kind of financial volatility - these surges and slumps in prices - matter? Perhaps it seems obvious. If you own something and it halves in value that's likely to be alarming, not to mention expensive. If you're going abroad on holiday you obviously don't relish discovering that the value of the currency in which you are paid has fallen by a tenth.
Perhaps it might even be ruinous if you were planning on selling a financial asset to realise the cash for something important such as paying off a debt that's falling due. Those who have borrowed in dollars and invested in bitcoin are unlikely to have had an enjoyable year. If you were planning to retire in 2019 and your pension has collapsed in value over the past 12 months you can also see the problem.
But all these examples assume the investor needs to realise the cash imminently. If you're saving for retirement several decades hence, even a 5 per cent daily swing, like the one we saw in US stocks on Boxing Day, is really neither here nor there.
What about the real economy? It's true that financial volatility can damage a normal business, perhaps even ruin it. Think of a goods importer that sees its import costs go up due to a currency slide. Think of a small oil driller that watches the value of the black stuff suddenly plummet. When those companies expire their workers can lose their jobs and livelihoods.
But it's necessary to separate out the micro from the macro. At an economy-wide level, idiosyncratic shocks will tend to balance out in the medium term. Sharply lower energy prices are bad for energy producers but good for energy consumers. A cheaper currency can be bad for importers but can be beneficial to exporters. A currency plunge certainly harms living standards by pushing up inflation. But the impact of a revaluation on prices is temporary if it's a one-off, as we've seen since the Brexit vote.
Some economists, such as Roger Farmer, think stock market crashes lead to domestic recessions. But the causality of that relationship is disputed. And as the Nobel economics laureate Paul Samuelson caustically observed, "The stock market has predicted nine of the past five recessions."
It would be fatuous to argue that financial market volatility doesn't matter at all for ordinary people. Yet it matters rather less than we're sometimes led to believe by the noise of excited speculators and the dramatic media headlines. Sometimes it's better not to pay too much attention to the puffs of smoke emitted by the chimney of markets.