We develop a stylized model of economic growth with bubbles in which changes in investor sentiment lead to the appearance and collapse of macroeconomic bubbles or pyramid schemes. These bubbles mitigate the effects of financial frictions. During bubbly episodes, unproductive investors demand bubbles while productive investors supply them. These transfers of resources improve economic efficiency thereby expanding consumption, the capital stock and output. When bubbly episodes end, there is a fall in consumption, the capital stock and output. We argue that the stochastic equilibria of the model provide a natural way of introducing bubble shocks into business cycle models.

This paper introduces various sources of consumer heterogeneity in one-sector representative consumer (RC) growth models and develops tools to study the evolution of the distribution of consumptions, assets, and incomes. These tools are applied to the Ramsey-Cass-Koopmans model of optimal savings and the Arrow-Romer model of productive spillovers. The RC property per se places very few restrictions on the nature of observed distributions, and a wide range of distributive dynamics and income mobility patterns can arise as the equilibrium outcome. An example illustrates how to use these tools to generate quantitative predictions and compare them to the data.

Conventional wisdom says that, in the absence of default penalties, sovereign risk destroys all foreign asset trade. We show that this conventional wisdom rests on one implicit assumption: that assets cannot be retraded in secondary markets. Without this assumption, foreign asset trade is possible even in the absence of default penalties. This result suggests a broader perspective regarding the origins of sovereign risk and its remedies. Sovereign risk affects foreign asset trade only if default penalties are insufficient and secondary markets work imperfectly. To reduce its effects, one can either increase default penalties or improve the working of secondary markets.

Over the last two decades US aggregate wealth has fluctuated substantially. Against the backdrop of the Great Recession, the effects of these boom-and-bust cycles have come to dominate academic and policy discussions. How can we explain these fluctuations in wealth? Why are these fluctuations associated with changes in consumption, investment and output? In this note, we argue that answers to these questions entail the addition of two ingredients to existent macroeconomic models: rational bubbles and financial frictions. We explain why each of these building blocks is crucial to understand recent events and how they can be seamlessly integrated in standard models.