A doubling strategy implies a relationship between a security’s return and its trading
volume. This relationship should be asymmetric: in the case of a long (short) position, a
price fall (rise) would be followed by a significant volume increase, while a price rise
(fall) would not. In addition, a trader following such a strategy may only start doubling
his position after the price crosses a certain threshold. This should be distinguished from
the information hypothesis that posits a contemporaneous or lagged relation from volumeto returns. Under this hypothesis, volume is proxying for the flow of information and
changes in investor’s expectations (Harris and Raviv, 1993). There has been some study
of the asymmetric relationship between volume and return. Karpoff (1988) and Suominen
(1996) suggest that in equity markets the observed positive correlation between volume
and returns can be explained by the presence of differential costs in acquiring short and
long positions. This asymmetry is not observed in futures markets, since the costs of
taking short and long positions in such markets are equal. For example, Kocagil and
Shachmurove (1998) calculate the contemporaneous correlation coefficients between the
two variables in 16 major U.S. futures markets and find no significant relationship4.
One rationalization for a doubling strategy is that it is a way to exploit market
inefficiencies, particularly where large volumes of trading can influence market prices.
Indeed Leeson (1996) defends his actions in these terms. This market inefficiency
explanation posits an intertemporal causality relationship running from volume to return