Von Insidern, „marginal traders“ und Glücksrittern: Zur Relevanz von Entscheidungsanomalien in politischen Börsen / About Insiders, Marginal Traders and Lucky Beggars in Political Stock Markets

In this paper we investigated three political stock markets, installed in Germany during three elections in 1990, 1991, and 1994. Markets of this type were first organized by Forsythe et al. (1992, 1993). As a result the predictive performance of the American markets was much better than that of opinion polls. In Germany markets worked quite good but none of them gave better predictions than the best polls did. As an explanation for the markets’ efficiency Forsythe et al. (1992) separate a subgroup of marginal traders capable to offset the judgement bias of other market participants. It is shown that a judgement bias also existed in the German markets. However, a group of marginal traders earning significantly higher returns could not be found. We argue that this approach is not adequate to explain the behavior within the German political stock markets. An alternative concept is therefore outlined with special regards to the institutional environment of the markets. Furthermore some theoretical aspects are discussed concerning the relationship between the marginal traders concept and the so-called Hayek hypothesis (see Smith 1982).