The bottom may soon be here.

SHORT VIEW作者：英国《金融时报》约翰•奥瑟兹(John Authers)The bottom may soon be here. This week's brutal sales of stocks across the world brought indices to historic levels. Harder questions are how far stocks must fall to get there, and how long it will take to climb out.In the US, stocks have shown a strong trend for more than a century, growing by 6.75 per cent per year after inflation, with income reinvested. London's Lombard Street Research points out there have been only 26 months in the past 140 years when the S&P 500 was further below this trend than it is now. All bar six, three each in 1932 and 1982, were caused by world wars.Those two years marked the lows of the worst bear markets of the last century. So stocks look likely to stop getting cheaper quite soon. But they could fall further before hitting bottom. In 1932, stocks fell 25 per cent more after becoming this cheap compared with trend – but then doubled in a matter of weeks.As for valuation, it is almost impossible to say that stocks are expensive. Cyclical earnings multiples, a reliable long-term value indicator, are now much cheaper than their average for the last century, although they again imply that one further big fall is possible before reaching their lows of 1932 and 1982. The sell-off goes beyond financials, as earnings multiples on non-financial stocks are approaching their lows from the last bear market. To take another measure, viewed in real terms, the S&P 500 was down 61.4 per cent at Monday's close since its peak in 2000. Its decline in real terms from 1929 to 1932 (when there was deflation) was 79 per cent, while the fall from 1969 to 1982 was 62.6 per cent. So any falls from here will be dictated by the economic data. And it is the strength of the economy that should dictate the speed of the recovery. After 1932, it took 26 years to regain the peak in real terms. After 1982, it took 10 years.