From the selection of the new lead in a Broadway musical, to forecasting Congressional elections, to the delivery delay of the Boeing 787 Dreamliner, prediction markets have solved a fascinating range of problems by aggregating the so-called wisdom of crowds. For many companies prediction markets have remained an interesting curiosity. But operating under-the-radar, a number of innovative companiesGeneral Electric and Google, Motorola and Microsoft, HP and Eli Lilly, plus the Central Intelligence Agencyhave tapped employee insights and used markets to make better decisions, and to allow employees to become visionaries. In Oracles, Don Thompson explains how these organizations use prediction markets to change how business gets done.