Prediction Market

A prediction market is a speculative market in which participants trade contracts whose payoff depends on the outcome of future events. The prices in a well-functioning prediction market aggregate dispersed information into a single probability estimate, often outperforming polls, expert panels, and statistical models. The theoretical basis is the efficient market hypothesis applied to information: traders with private information have a financial incentive to reveal it through their trades, and the equilibrium price reflects the weighted aggregation of all available information.

Prediction markets have been proposed as mechanisms for improving institutional decision-making. Robin Hanson has argued that organizations should replace traditional managerial discretion with futarchy: a system in which democratic institutions set values but prediction markets choose policies. The proposal remains controversial — critics argue that markets can be manipulated, that participation is skewed toward wealthy actors, and that some decisions (particularly those involving existential risk) should not be subject to financial speculation.

The empirical record of prediction markets is mixed. They performed well in forecasting election outcomes and corporate earnings but have failed in domains where information is highly dispersed, where manipulation is profitable, or where the event being predicted is so far in the future that no trader has meaningful information. The question of where prediction markets work — and where they systematically fail — is an open problem in institutional design.