We develop a model of banking industry dynamics to study the quantitative impact of capital requirements on equilibrium bank risk taking, commercial bank failure, interest rates on loans, and market structure. We propose a market structure where big banks with market power interact with small, competitive fringe banks. Banks face idiosyncratic funding shocks in addition to aggregate shocks to the fraction of performing loans in their portfolio. A nontrivial bank size distribution arises out of endogenous entry and exit, as well as banks' buffer stock of net worth. We show the model predictions are consistent with untargeted business cycle properties, the bank lending channel, and empirical studies of the role of concentration on financial stability. We then conduct a series of counterfactuals (including countercyclical and size contingent (e.g. SIFI) capital requirements). We find that regulatory policies can have an important impact on market structure in the banking industry which, along with selection effects, can generate changes in allocative efficiency.

The impact of capital market imperfections and costs of creating and operating formal sector firms on total factor productivity is studied. We propose a firm dynamics model with endogenous formal and informal sectors where firms face a technology adoption opportunity. The model predicts that countries with a low degree of debt enforcement and high costs of formality are characterized by low allocative efficiency and large output shares produced by low productivity, informal sector firms. For frictions parametrized using the Doing Business database, the model generates a drop in total factor productivity of up to 25% relative to the US.

The question of what is a sustainable public debt is paramount in the macroeconomic analysis of fiscal policy. This question is usually posed as asking whether the outstanding public debt and its projected path are consistent with those of the government's revenues and expenditures (i.e. whether fiscal solvency conditions hold). We identify critical flaws in the traditional approach to evaluate debt sustainability, and examine three alternative approaches that provide useful econometric and model-simulation tools to analyze debt sustainability. The first approach is Bohn's non-structural empirical framework based on a fiscal reaction function that characterizes the dynamics of sustainable debt and primary balances. The second is a structural approach based on a calibrated dynamic general equilibrium framework with a fully specified fiscal sector, which we use to quantify the positive and normative effects of fiscal policies aimed at restoring fiscal solvency in response to changes in debt. The third approach deviates from the others in assuming that governments cannot commit to repay their domestic debt, and can thus optimally decide to default even if debt is sustainable in terms of fiscal solvency. We use these three approaches to analyze debt sustainability in the United States and Europe after the recent surge in public debt following the 2008 crisis, and find that all three raise serious questions.

This paper uses a dynamic political economy model to evaluate whether the observed rise in wage inequality can explain an increase in transfers and effective tax rates in the U.S. over the past two decades. Specifically, we assume that households have uninsurable idiosyncratic labor efficiency shocks and consider policy choices by a median voter which are required to be consistent with a sequential equilibrium. We deal with the problem that policy outcomes affect the evolution of the wealth distribution by approximating the distribution by a small set of moments. We calibrate the model to match properties of the U.S. earnings distribution and effective tax rates in 1983 and then evaluate the response of the social insurance policies to the observed rise in wage inequality over the next decade and a half. This increase in wage dispersion is capable of explaining over two-thirds of the increase in effective taxes observed in the data while a utilitarian approach would explain only one-third31 of the change.