Contemporary social theorists usually conceive of risk negatively. Focusing on disasters and hazards, they see risk as an object of calculation and avoidance. But we gain a deeper understanding of risk in modern life if we observe it in another setting. Futures markets are exemplary sites of aggressive risk taking. Drawing upon extensive fieldwork on trading floors, this article shows how a high modern institution creates populations of risk-taking specialists, and explores the ways that engagements with risk actively organize contemporary markets and forge economic actors. Financial exchanges are crucibles of capitalist production. At the Chicago Board of Trade, financial speculators structure their conduct and shape themselves around risk; and games organized around risk influence the social and spatial dynamics of market life.