What a little moonlight can do
How the sun and the moon move markets
WHEN ace traders call themselves âMasters of the Universeâ, they speak truer than they know. There is a growing, heavenly body of evidence that share prices are influenced by forces from outer spaceâwell, the sun and the moon, anyway. Master these inter-planetary forces, and you master the markets.
Seven souls have boldly gone where no economists have gone before, producing no fewer than three new papers quantifying extra-terrestrial influences at work in world stockmarkets. David Hirshleifer, of Ohio State University, and Tyler Shumway, of the University of Michigan, have taken a long look at the sun. Across 26 stockmarkets, in 1982-97, they found that, on days with more sunshine in the morning than usual, shares generated above-average gains, and lower gains on unusually cloudy days. After taking sunshine into account, other weather conditions such as snow or rain turned out to have no impact on share returns.
The effect of the sun seems to have been quite big. For shares traded in New York, for instance, annualised returns on perfectly sunny days averaged 24.8%, compared with 8.7% on perfectly cloudy days. Moreover, unlike some stockmarket âanomaliesâ discovered by economists, investing by the sun would have been more profitable than simply investing in the market index, even after subtracting trading costs. Alas, this does not guarantee profitable trading in the future. Even assuming the effect really exists, investors, now they have been alerted to it, will probably arbitrage away any excess returns to be had by exploiting it.