Institutions affect prospects for economic growth and development. In this paper a condition on the primitives determines whether an economy supports markets. Agents differ in land holdings, skill, and power. A competitive market assigns land efficiently to the skilled, not necessarily to the powerful. Therefore a market allocation needs to be stable with respect to coalitional expropriation. More equally distributed power and higher congruence of land and power favor stable markets. In a dynamic setting, we identify conditions that ascertain whether markets are stable forever, or alternate with expropriation in a limit cycle, decreasing efficiency and amplifying macroeconomic fluctuations.