These tailwinds have turned.
Covid-19 messed up supply chains; war and sabre-rattling are undermining globalisation.
Manoj Pradhan, formerly of Morgan Stanley, points out that China’s working-age population has peaked.
Jeremy Grantham, a bearish hedge-fund investor, fears that the switch to renewables will be slow and costly, and that lower investment in fossil-fuel production will make it hard for energy firms to ramp up supply, increasing the risk of energy-price spikes.
All this, the structuralists argue, means the current inflation shock is likely to be the first of many: central bankers will be playing whack-a-mole for a while yet.
Recurrent inflation would upend 20 years of portfolio-management strategy.
If the correlation between stocks and bonds shifts from -0.5 to +0.5 the volatility of a “60/40” portfolio increases by around 20%.
In a bid to avoid being wrong-footed once again, investors are updating their plans.
As Barry Gill of UBS’s asset-management arm puts it, the task is “to realign your portfolio around this new reality”.
What assets will allow investors to sleep soundly in this new reality?
Cryptocurrencies once looked like an interesting hedge, but this year they have fallen and risen in lockstep with stocks.
A recent paper by KKR, a private asset-management firm, argues, perhaps unsurprisingly, that illiquid alternatives, like private equity and credit, are a good way to diversify.
But that may be an illusion: illiquid assets are rarely marked-to-market, and are exposed to the same underlying economic forces as stocks and bonds.
There are other options.
AQR suggests stock-picking strategies where success has little to do with broader economic conditions, such as “long-short” equity investing (going long on one firm and short on another).
Meanwhile, commodities are the natural choice for those worried about a disorderly green transition, since a basket of them appears to be uncorrelated with stocks and bonds over long periods.
In the search for new ways to minimise risk, investors dreaming of high returns will have to get creative.
That, at least, should tire them out by the end of the day.