Financial activity has become increasingly important in affluent economies in recent decades. Because this ‘financialization’ distributes costs and benefits unevenly across groups, politics and policy likely affect the process. Therefore, this article discusses how changes in the power of organizations representing the ‘winners’ and ‘losers’ of financialization affect its pace. An analysis of the United States from 1949–2005, shows that when unions are stronger, and when the Democratic Party is in power and is more reliant on the support of working-class voters, financialization is slower. In contrast, when the financial industry is more highly mobilized into politics, financialization is faster. The study also finds that financial deregulation was one policy translating the political power of these actors into economic outcomes.