Historically, urban growth required enough development to grow and transport significant agricultural surpluses or a government effective enough to build an empire. But there has been an explosion of poor mega-cities over the last thirty years. A simple urban model illustrates that in closed...

Modern open economy macro models assume the continuous adjustment of international portfolio allocation. We introduce gradual portfolio adjustment into a global equity market model. Our approach differs from related literature in two key dimensions. First, the time interval between portfolio...

We introduce a portfolio friction in a two-country DSGE model where investors face a constant probability to make new portfolio decisions. The friction leads to a more gradual portfolio adjustment to shocks and a weaker portfolio response to changes in expected excess returns. We apply the model...