I study how the density of executive labor markets affects managerial incentives and thereby firm performance. I find that U.S. executive markets are locally segmented rather than nationally integrated, and that the density of a local market provides executives with non-compensation incentives. Empirical results show that in denser labor markets, executives face stronger performance-based dismissal threats as well as better outside opportunities. These incentives result in higher firm performance in denser markets, especially when executives have longer career horizons. Using state-level variation in the enforceability of covenants not to compete, I find that the positive effects of market density on incentive alignment and firm performance are stronger in markets where executives are freer to move. This evidence further supports the argument that local labor market density works as an external incentive alignment mechanism.