We argue that market failure is a major and growing source of income inequality in the United States and in liberal market economies (LMEs) more generally. This market failure takes the form of occupational, educational, managerial, and capital rents that are generated by institutional barriers that restrict the free flow of capital or labor. We suggest that these four forms of rent can partly account for (a) the extreme income inequality at the very top of the LME income distribution as well as (b) the extreme income inequality that is also observed beneath the highest percentiles of the income distribution. The sharp increase in these forms of rent, when coupled with rent destruction at the bottom of the labor market, may well explain much of the takeoff in LME inequality in the past four decades. We conclude by outlining the empirical research agenda and policy prescription implied by a rent-based account.