With stock markets falling day by day, investment gurus suggest it is time to buy – taking a 30-year view. Certainly, there are plenty of companies across the developed world in little immediate danger and trading at eyewateringly low prices. But there is no telling how long a market recovery could take. The Dow Jones Industrial Average took 24 years to regain its pre-crash highs following the Great Depression. Japanese equities are still a quarter of what they were almost 20 years ago.

For many, that will be too long a wait. Assume, for example, that the US market takes half as long to recover as after the 1929 crash (because it has fallen by half as much). That is an average annual return of 4.5 per cent. On that basis, nobody over the age of 65 will ever see the market hit a new high, based on current life expectancies – some 12 per cent of the US population. Add 10 years to the recovery time and a quarter of Americans could have share portfolios that never break new ground in their lifetimes.