The interaction of incomplete markets and sticky nominal wages is shown to magnify business cycles even though these two features – in isolation – dampen them. During recessions, fears of unemployment stir up precautionary sentiments which induces agents to save more. The additional savings may be used as investments in both a productive asset (equity) and an unproductive asset (money). But even a small rise in money demand has important consequences. The desire to hold money puts deflationary pressure on the economy, which, provided that nominal wages are sticky, increases wage costs and reduces firm profits. Lower profits repress the desire to save in equity, which increases (the fear of) unemployment, and so on. This is a powerful mechanism which causes the model to behave differently from both its complete markets version, and a version with incomplete markets but without aggregate uncertainty. In contrast to previous results in the literature, agents uniformly prefer non-trivial levels of unemployment insurance.
Increases in uncertainty lead to increases in the unemployment rate. Using US data, I show empirically that this is due to both an increase in the separation rate and a decrease in the job-finding rate. By contrast, standard search and matching models predict an increase in the job finding rate in response to an increase in the cross-sectional dispersion of firms’ productivity levels. To explain observed responses in labour market transition rates, I develop a search and matching model in which heterogeneous firms face a decreasing returns to scale technology, firms can hire multiple workers, and job flows (job creation and job destruction) do not necessarily coincide with worker flows (hires and separations). Costly job creation (in addition to the usual hiring cost) is key to obtaining a decrease in the job-finding rate after an increase in uncertainty. Standard numerical solution techniques cannot be used to obtain an accurate solution efficiently and I propose an alternative algorithm to overcome this problem.