Competitive equilibria with limited enforcement

We show how to decentralize constrained efficient allocations that arise from enforcement constraints between sovereign nations. In a pure exchange economy these allocations can be decentralized with private agents acting competitively and taking as given government default decisions on foreign debt. In an economy with capital these allocations can be decentralized if the government can tax capital income as well as default on foreign debt. The tax on capital income is needed to make private agents internalize a subtle externality. The decisions of the government can arise as an equilibrium of a dynamic game between governments.     

Optimal asset taxes in financial markets with aggregate uncertainty

This paper studies Pareto-optimal risk-sharing arrangements in a private information economy with aggregate uncertainty and ex ante heterogeneous agents. I show how to implement Pareto optima as equilibria when agents can trade claims to consumption contingent on aggregate shocks in financial markets. The first result is that if aggregate and idiosyncratic shocks are independent, the implementation of optimal allocations does not require any interventions in financial markets. This result can be extended to dynamic settings in the sense that, in this case, only savings need to be distorted, but not trades in financial markets. Second, I characterize optimal trading distortions in financial markets when aggregate and idiosyncratic shocks are not independent. In this case, optimal asset taxes must be higher for those securities that pay out in aggregate states in which consumption is more volatile. For instance, this can provide an efficiency justification for the frequently observed differential tax treatment of different asset classes, such as debt and equity claims.     

Uninsured idiosyncratic risk, liquidity constraints and aggregate fluctuations

Summary. I study the role played by uninsured idiosyncratic risk and liquidity constraints in the propagation of aggregate fluctuations. To this purpose, I compare the aggregate fluctuations of two model economies that differ in their insurance technologies only. In one of these model economies liquidity constrained households vary their holdings of a nominally denominated asset in order to buffer an uninsured idiosyncratic shock to their individual production opportunities. In the other economy every idiosyncratic component of risk can be costlessly insured. I find that the limited insurance technology implies fluctuations in output that are 20% larger, fluctuations in hours relative to output that are 9% larger, fluctuations in consumption relative to output that are 18% smaller, and a correlation of hours and productivity that is 15% smaller than those that obtain under the full insurance technology. Received: March 6, 1996; revised version August 15, 1996     

Country Default Risk: An Empirical Assessment

We provide benchmarks to evaluate what is an optimal foreign debt and a maximal foreign debt ( debt-max ), when risk is explicitly considered. When the actual debt exceeds debt-max , then the economy will default when a 'bad shock' occurs. This paper is an application of the stochastic optimal controls models of Fleming and Stein (2001), which gives empirical content to the question of how one should measure 'vulnerability' to shocks, when there is uncertainty concerning the productivity of capital. We consider two sets of high-risk countries during the period 1978–99: a subset of 21 countries that defaulted on the debt, and another set of 13 countries that did not default. Default is a situation where the firms or government of a country reschedule the interest/principal payments on the external debt. We thereby explain how our analysis can anticipate default risk, and add another dimension to the literature of early warning signals of default/credit risk.     

Incomplete markets,liquidation risk,and the term structure of interest rates

We analyse the term structure of interest rates in a general equilibrium model with incomplete markets, borrowing constraint, and positive net supply of government bonds. Uninsured idiosyncratic shocks generate bond trades, while aggregate shocks cause fluctuations in the trading price of bonds. Long bonds command a “liquidation risk premium” over short bonds, because they may have to be liquidated before maturity – following a bad idiosyncratic shock – precisely when their resale value is low – due to the simultaneous occurrence of a bad aggregate shock. Our framework endogenously generates limited cross-sectional wealth heterogeneity among the agents (despite the presence of uninsured idiosyncratic shocks), which allows us to characterise analytically the shape of the entire yield curve, including the yields on bonds of arbitrarily long maturities. Agents? desire to hedge the idiosyncratic risk together with their fear of having to liquidate long bonds at unfavourable terms implies that a greater bond supply raises the level of the yield curve, while an increase in the relative supply of long bonds raises its slope.     

Asset prices in a Huggett economy

This paper explores asset pricing in economies where there is no direct insurance against idiosyncratic risks but other assets can be used for self-insurance, subject to exogenously-imposed borrowing limits. We analyze an endowment economy, based on Huggett (1993) [11], both with and without aggregate risk. Our main innovation is that we obtain full analytical tractability by studying the case with “maximally tight” borrowing constraints. We illustrate by looking at riskless bonds, equity, and the term structure of interest rates, and we show that the model can reproduce many features of observed asset prices when idiosyncratic risks are quantitatively reasonable.     

Precautionary saving or denied dissaving

Precautionary saving in response to uninsurable income risk can in principle explain the stylized fact that aggregate saving increases with the variance of income, but it is controversial how much of the observed variation in incomes is, in fact, unpredictable. Borrowing constraints offer an alternative explanation that does not require consumers to be uncertain about their future income. This paper employs a three-cohort, overlapping generations model with quadratic utility and no capital to show that, if agents are patient enough, heterogeneity alone can account for more than half the decrease in the equilibrium interest rate caused by a borrowing constraint. The possibility of facing a binding borrowing constraint in the future induces saving, and this saving increases with the cross-sectional variation in income. Another channel that pushes down the interest rate is the direct effect caused by currently constrained agents not being allowed to dissave. For patient agents, the two channels have roughly the same impact on the interest rate.     

IDIOSYNCRATIC AND AGGREGATE RISKS,INEQUALITY AND GROWTH

The paper disaggregates productivity shocks at a firm level into idiosyncratic and aggregate risks, and studies their impacts on inequality, growth and welfare. It develops a growth model with human capital and incomplete insurance and credit markets that provides a closed‐form solution for income inequality dynamics. We find that uninsured idiosyncratic risks are the most important determinants of inequality, growth and welfare. They are the source of nondegenerate wealth distribution. A lower weight of these shocks leads to lower steady‐state inequality, higher growth and welfare. A redistribution of income that serves as social insurance against such risks increases welfare and decreases inequality. But, it also decreases growth by distorting individual consumption and saving decisions.     

On the disaggregation of excess demand functions when prices and aggregate income vary independently

Under the assumption that prices and aggregate income can vary independently and that the income distribution scheme is known and homogeneous of degree 1 in prices and aggregate income, I raise the question of the restrictions on aggregate excess demand behavior implied by the postulate of rationality of individual agents. If the number of agents is at least as high as the number of commodities, aggregate excess demand need not satisfy, at a point, any restrictions other than homogeneity of degree 0 and Walras' law. Furthermore, if the number of agents, m, is less than the number of commodities, l, aggregate excess demand can be locally arbitrary when projected on an m-dimensional subspace of the commodity space.     

Sequential procurement auctions with risk-averse suppliers

We compare two procurement mechanisms, bundling and unbundling, in a two-stage auction model with risk-averse suppliers. The mechanisms differ in that the two tasks of investment and production are procured through a single auction or two sequential auctions. Suppliers’ production costs are affected by two risk factors, aggregate risk and idiosyncratic risk, as well as by the cost-reducing investment. We show that the bundling mechanism is optimal for a buyer and socially desirable if the aggregate risk is below certain thresholds. The result may not hold true for idiosyncratic risk.     

Crowding out and crowding in: When does redistribution improve risk-sharing in limited commitment economies?

When the risk of default constrains financial contracts, public insurance policies can significantly affect private risk-sharing. This is because by changing income expectations and volatility, redistribution changes the attractiveness of default and thus endogenous borrowing constraints. Extending results by Krueger and Perri (2011) [8], this paper analyses the conditions under which redistribution can improve private insurance by making default less attractive to the income-rich, whose income it reduces. I first explain why public redistribution typically crowds out private insurance in the two-income economy, and identify the role of income persistence and saving after default. Second, I show how, in endowment economies with three income states or more and in economies with capital, redistributive taxes can improve, or “crowd in”, private consumption insurance. Finally, in a quantitative exercise using a realistic income process calibrated to US micro-data, moderate redistribution crowds in private insurance with production but not in an endowment economy.     

Optimal Loan Loss Provisions and Welfare

We study the welfare implications of optimal loan loss provisions in a New Keynesian model featuring endogenous default risk and inflationary credit spreads. A unique link between provisions, credit spreads and inflation can be employed to enhance macroeconomic stability. Optimal provisions are most effective when dealing with cost-push financial shocks inherent in volatile spreads and the zero bound problem of monetary policy. Relaxing provisioning requirements following a recessionary financial disturbance consistently achieves the first-best outcome while nullifying the value of monetary policy under commitment. In contrast, deflationary demand shocks warrant an optimal rise in provisions, which inflate prices yet mildly contract output.     

Optimal age‐dependent income taxation in a dynamic extensive model: The case for negative participation tax on young people

We consider optimal age‐dependent income taxation in a dynamic model where the labor‐leisure choice is the extensive margin, each household faces idiosyncratic shocks to labor productivity and a pecuniary cost to work, and there is no insurance market against the shocks. We show that the well‐known property of the optimal participation tax rate in the static model continues to hold in our dynamic economy, that is, the participation tax rates for some income groups with low consumption are likely negative. In dynamic models, the optimal participation tax rate depends on age and on labor income. Our numerical simulations suggest that a negative participation tax should be restricted to young households.     

Nonseparable preferences and optimal social security systems

In this paper, we consider economies in which agents are privately informed about their skills, which evolve stochastically over time. We require agents' preferences to be weakly separable between the lifetime paths of consumption and labor. However, we allow for intertemporal nonseparabilities in preferences like habit formation. In this environment, we derive a generalized version of the Inverse Euler Equation and use it to show that intertemporal wedges characterizing optimal allocations of consumption can be strictly negative. We also show that preference nonseparabilities imply that optimal differentiable asset income taxes are necessarily retrospective in nature. We show that under weak conditions, it is possible to implement a socially optimal allocation using a social security system in which taxes on wealth are linear, and taxes/transfers are history-dependent only at retirement. The average asset income tax in this system is zero.     

Corporate governance and default prediction: a reality test

Default prediction has commanded the attention of researchers for at least 50 years. This paper addresses several testable hypotheses regarding the relations between corporate governance and default prediction. We employ the conventional logistic regression to provide empirical evidence from U.S. default data over the period of 2000 to 2015. Empirical results are consistent with the following notions: First, default firms are associated with high ownership concentration, low shareholder rights, low financial transparency and disclosures, and less board effectiveness. Second, in-sample and out-of-sample tests support the incremental contribution of corporate governance information on default prediction, when compared with the models involving just financial information.     

When is market incompleteness irrelevant for the price of aggregate risk (and when is it not)?

In a standard incomplete markets model with a continuum of households that have constant relative risk aversion (CRRA) preferences, the absence of insurance markets for idiosyncratic labor income risk has no effect on the premium for aggregate risk if the distribution of idiosyncratic risk is independent of aggregate shocks and aggregate consumption growth is independent over time. In equilibrium, households only use the stock market to smooth consumption; the bond market is inoperative. Furthermore, the cross-sectional distributions of wealth and consumption are not affected by aggregate shocks. These results hold regardless of the persistence of idiosyncratic shocks, even when households face tight solvency constraints. A weaker irrelevance result survives when we allow for predictability in aggregate consumption growth.     

Multi-dimensional risk and the cost of business cycles

This paper analyzes the welfare costs of business cycles when workers face uninsurable idiosyncratic labor income risk. In accordance with the previous literature, this paper decomposes labor income risk into an aggregate and an idiosyncratic component, but in contrast to the previous literature, this paper allows for multiple sources of idiosyncratic labor income risk. Using the multi-dimensional approach to idiosyncratic risk, this paper provides a general characterization of the welfare cost of business cycles when preferences and the (marginal) process of individual labor income in the economy with business cycles are given. The general analysis shows that the introduction of multiple sources of idiosyncratic risk never decreases the cost of business cycles, and strictly increases it if there are cyclical fluctuations across the different sources of risk. This paper also provides a quantitative analysis based on a version of the model that is calibrated to match US labor market data. The quantitative analysis suggests that realistic variations across two particular dimensions of idiosyncratic labor income risk increase the welfare cost of business cycles by a substantial amount.     

Feasible Net Income Distributions under Income Tax Evasion: An Equilibrium Analysis

We investigate how redistribution of income is affected by the fact that income is privately observed and agents may not be truthful in their reports to tax authorities. In response, the government establishes an audit mechanism with penalties. Adhering to a signaling equilibrium concept, we prove that agents resort to mixed strategies, which makes it difficult for tax authorities to identify the true types. The audit strategy has a cutoff property: All income declarations below the pivotal income are audited with a constant probability; other declarations are not audited. In spite of not necessarily being truthful, agents whose true income is below or equal to the pivotal income pay their liability and, consequently, the government is implementing the designated tax schedule for those agents. In equilibrium, penalties and tax corrections equal the audit cost. Consequently, the audit system does not contribute directly to revenues, and its role is restricted to supporting the equilibrium.     

Selecting a unique competitive equilibrium with default penalties

The enlargement of the general-equilibrium structure to allow for default subject to penalties results in a construction of a simple mechanism for selecting a unique competitive equilibrium. We consider economies for which a common credit money can be applied to uniquely select each of the competitive equilibria with suitable default penalties. We identify two classes of such economies.     

Monetary policy under a fiscal theory of sovereign default

This paper examines equilibrium determination under different monetary policy regimes when the government might default on its debt. We apply a cash-in-advance model where the government does not have access to non-distortionary taxation and does not account for initial outstanding debt when it sets the income tax rate. Solvency is then not guaranteed and sovereign default can affect the return on public debt. If the central bank sets the interest rate in a conventional way, the equilibrium allocation cannot be determined. If, instead, money supply is controlled, the equilibrium allocation can uniquely be determined.