The rise in popularity of online trading platforms has attracted millions of new investors and speculators to global financial markets in the past couple of years - two years that, until late January 2018, had only seen stock markets move higher.
This point is important, as the slump in equity prices seen across many global stock indices, would have been a brand-new experience for many thousands of traders cutting their teeth in market speculation.
On 26 January 2018, the S&P 500 index in New York closed at a new record high of 2,872.87. Over the next 10 trading sessions it fell to a four-month low of 2,532.67 - a loss of 11.8% in just two weeks. Such a loss - of more than 10% (but less than 20%) - is called a correction.
Corrections are always difficult to spot coming and often not easy to call an end to, either. The recent sell-off was likely exacerbated by panic selling from those positioned long (backing price rises) into the correction using leveraged finance.
More experienced investors holding physical stock, however, would have suspected a correction was under way and ridden it out.
Although the S&P 500 has, since hitting that four-month low on 9 February, recovered nearly two-thirds of its losses, market participants remain on edge. The Vix index of S&P 500 market volatility remains close to the notional “fear zone” of 20.
While the recent correction may have been triggered by concerns over the policy response to rising global inflation - corrections tend to happen when equity valuations rise to levels that cannot be supported by earnings expectations.
Looking at the simplest measure of equity valuation - the price/earnings (PE) ratio - we can see that, historically speaking, prices remain on the high side, even after the recent correction.
By taking a company's earnings per share - let's say $2 - and dividing this into its current share price - for example $20 - you'd come up with a PE ratio of 10.
By averaging out all the PE ratios on the S&P 500, and then averaging all the annual levels over time, the benchmark US index has an average PE ratio of 18.1. As of 22 February - according to data from Capital Economics - the S&P 500's current PE stands at 25.2. That's 39% higher than the historical average.
Meanwhile, measures such as CAPE - the cyclically adjusted price earnings ratio - is still at a level that has only been topped twice in the past century: both times severe market recessions followed - the stock market crash of 1929 and the dotcom bubble of 2000-02.
Prices, then, remain on the lofty side and, some could say, susceptible to further correction. But valuations can be misleading - particularly during periods of economic strength that are robust enough to keep earnings growth momentum supported.
"We have long argued that the 'normal' level of the CAPE is much higher than this average," says John Higgins, chief markets economist at Capital Economics.
"This is because we think that a secular decline in interest rates has reduced the normal return available from 'risk-free' assets, and that this in turn has lowered investors’ normal required return from equities."
Earnings provide support
Nevertheless, it has been another broadly-positive earnings season, with fourth-quarter 2017 earnings expectations being beaten by three-quarters of those companies that have reported on the S&P 500 so far.
Furthermore, earnings are topping analysts' expectations by an average of 4.8%, beating the average of 4.7% seen over the previous three years, according data from Credit Suisse.
But earnings and valuations aren't everything. Some believe there are growing fundamental reasons to be cautious of pushing the markets into further record territory.
Ian Shepherdson at Pantheon Macroeconomics believes that not only is the correction not over, but that something far worse could be on the way due to the slow rate of productivity growth in the US coupled with fiscal concerns over the country's widening budget and current account deficits.
"Slow productivity growth helped create the illusion that deficits don't matter," he says, allowing the US to avoid difficult fiscal decisions and "making it appear costless to take dumb decisions."
Because this process played out over a long period, says Shepherdson, the illusion took a powerful hold over policymakers, investors and commentators. And now China is no longer buying Treasuries, just as issuance to pay for President Trump's tax cuts is about to rocket.
"In other words, the forces which have held down real yields since the turn of the century are now starting to work in the opposite direction.
"The check for the free lunch is now arriving," he says.
Such a wholesale plunge in risk appetite would be damaging for equity and bond markets alike, if such predictions become a reality the result could plunge equities into a bear market downturn - losses exceeding 20%.
But while growth predictions in the US remain robust, no-one's worrying much about the twin deficits and equities have resumed their march higher.
At the current momentum, and if the correction really is over, the S&P 500 should be mounting another assault on its record peak before the end of March.
But watch out for those sleeping bears. They wake up hungry.