通货膨胀和股权收益(2)

There are competing theories for the inverse relationship; many date from the late 19705 and early 1980s. A paper written by Franco Modigliani and Richard Cohn in 1979 put it down to "money ilusion":
rising inflation leads to fllig stock prices because investors discount future earnings by reference to higher nominal bond yields. The correct discount factor is a real yield (ie, excluding compensation for expected inflation).
Other theories said that inflation is merely a reflection of deeper forces that hurt stock prices; an overheating economy; rising uncertainty; political instability.
In the decades since then, inflation has steadily declined. Stocks have re -rated. Investors have been willing to pay an ever- higher price for a given stream of future earnings.
You might put this down to the Modigliani Cohn effect in reverse, since nominal bond yields have also fallen. But so too have long term real bond yields. The real rate of interest needed to keep inflation stable is lower.
Now for the headache. For the most part, financial markets reflect the view that inflation will remain low. Nominal bond yields are negative in much of Europe and barely positive in America. In stockmarkets, there has for a while been a sharp divide.
Companies that do well in disinflationary environments (technology, branded goods) are expensive; businesses that might do better in inflationary ones (commodities, real estate and banking) have generally lagged behind.
The immediate prospect is indeed for an excess of supply. The unemployment rate in America is close to 15%. Infation is already flling. Further out, though, the outlook for inflation is murkier. There is no shortage of pundits who say it is primed to pick up. They have a case.
Globalisation, a key reason for the secular decine in inflation, is reversing. Big companies are likely to emerge from the crisis with more pricing power. The rise of populism in rich countries is hard to square with endlessly low inflation. Fiscal stimulus is in favour.
The more government debt piles up, the greater the temptation to try to inflate it away. For all such speculation, it is far from clear whether, how fast and by how much inlation might rise.
A modest pickup might even be good for stock prices especially in Europe, where bourses are tilted towards the cylical stocks most hurt by unduly low inflation. But it is foolish to believe that inflation will leave your stock portfolio unharmed--and too easy to forget the damage it can do.