The recent stock market rebound has been almost as sharp and rapid as the sudden plunge that preceded it. Although markets "went from 1929 to 1999 in a week", as Morgan Housel of the Collaborative Fund puts it, the mood on Wall Street remains cautious, with Goldman Sachs, JPMorgan and Bank of America all stressing that investors shouldn't assume that the bottom is in. One can see why. Firstly, markets "rarely clear after one massive decline", points out Gavekal Research. Of the 15 bear markets since 1950, the initial major low was retested on all but one occasion. Secondly, the recent rebound means stocks are now back to where they were just 10 months ago, even though the economic and earnings outlook is infinitely darker than it was then.

JPMorgan estimates the coronavirus will cost the global economy $5.5 trillion in lost economic output, or almost 8 per cent of GDP. Deutsche Bank expects the European and US economies to remain well below pre-virus expectations by the end of 2021. As for corporate earnings, "making assumptions on future profit growth is almost impossible", says Barclays. Thirdly, there is increased optimism that the spread of the virus is levelling off, but that is a consequence of extensive lockdown measures and there is "no clear exit strategy", as Prof Neil Ferguson, whose research is informing policy in the UK, the US and beyond, admitted last week. Stocks may well have bottomed, but the outlook remains hugely uncertain. Further market scares would be no great surprise.