To study coordination in complex social systems such as financial markets, the authors introduce a new prediction market set-up that accounts for fundamental uncertainty. Nonetheless, the market is designed so that its total value is known, and thus its rationality can be evaluated. In two...

Online sports betting is growing rapidly around the world. We describe how the competitive structure of the bookmaking market affects odds when bettors disagree about the probabilities of the outcomes of sporting events but are on average correct. We show that the demand for bets on longshots is...