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What are the effects of a temporary lockdown of the economy? Do firms' deteriorating balance sheets and labor market frictions propagate and prolong the effects? We answer these questions in a model with financial and labor market frictions. The model makes quantitative predictions about the effect of lockdowns of varying magnitude and duration on output, employment and firm dynamics. We find that the effects are not persistent if (i) workers on temporary layoff can be recalled by their previous employers without having to go through the frictional labor market and (ii) the government provides employment subsidies to firms during the lockdown. However, the effects are heterogeneous and young non-essential firms are disproportionately affected. In addition, if lockdowns lead to more permanent reallocation across industries, the recession becomes more protracted. Although the paper is motivated by the lockdowns during the Covid-19 pandemic, the framework can be readily applied to large, temporary shocks of different nature.

Why don't poor countries adopt more productive technologies? Is there a role for policies that coordinate technology adoption? To answer these questions, we develop a quantitative model that features complementarity in firms' technology adoption decisions: The gains from adoption are larger when more firms adopt. When this complementarity is strong, multiple equilibria and hence coordination failures are possible. More important, even without equilibrium multiplicity, the model elements responsible for the complementarity can substantially amplify the effect of distortions and policies. In what we call the Big Push region, the impact of idiosyncratic distortions is over three times larger than in models without such complementarity. This amplification enables our model to nearly fully account for the income gap between India and the US without coordination failures playing a role.

We study the interactions between sovereign debt default and maturity choice in a setting with limited commitment for repayment as well as future debt issuances. Our main finding is that, under a wide range of conditions, the sovereign should, as long as default is not preferable, remain passive in long‐term bond markets, making payments and retiring long‐term bonds as they mature but never actively issuing or buying back such bonds. The only active debt‐management margin is the short‐term bond market. We show that any attempt to manipulate the existing maturity profile of outstanding long‐term bonds generates losses, as bond prices move against the sovereign. Our results hold regardless of the shape of the yield curve. The yield curve captures the average costs of financing at different maturities but is misleading regarding the marginal costs.

This paper considers the design of an optimal rating system, in a market with adverse selection. We address two critical questions about rating design: First, given a number of categories, what are the criteria for setting the boundaries between them? Second, what are the gains from increasing the number of categories? A rating system helps reallocate sales from lower- to higher-quality producers, thus mitigating the problem of adverse selection. We focus on two main sources of market heterogeneity that determine the extent and effect of this reallocation: the distribution of firm qualities and the responsiveness of sellers' supply to prices. We provide a simple characterization for the optimal rating system as the solution to a standard k-means clustering problem, and discuss its connection to supply elasticity and the skewness of firm qualities. Our results show that a simple two-tier rating can achieve a large share of full information surplus. Additionally, we characterize the conflicting interests of consumers and producers in the design of a rating system.

Firm size increases with GDP per capita. The paper develops a simple framework to explore three alternative sources of variation that may explain this correlation: (1) excessive entry; (2) differences in the distribution of firm productivities; and (3) differences in returns to scale. The results show that all these sources of variation lead to substantial differences in firm size. GDP per capita is also significantly affected, but by an order of magnitude less. JEL classifications: O11, E13

We propose a theory linking imperfect information to resource misallocation and hence to aggregate productivity and output. In our setup, firms look to a variety of noisy information sources when making input decisions. We devise a novel empirical strategy that uses a combination of firm-level production and stock market data to pin down the information structure in the economy. Even when only capital is chosen under imperfect information, applying this methodology to data from the United States, China, and India reveals substantial losses in productivity and output due to the informational friction. Our estimates for these losses range from 7% to 10% for productivity and 10% to 14% for output in China and India, and are smaller, though still significant, in the United States. Losses are substantially higher when labor decisions are also made under imperfect information. We find that firms turn primarily to internal sources for information; learning from financial markets contributes little, even in the United States.

The US economy has undergone a number of puzzling changes in recent decades. Large firms now account for a greater share of economic activity, new firms are being created at a slower rate, and workers are getting paid a smaller share of GDP. This paper shows that changes in population growth provide a unified quantitative explanation for these long-term changes. The mechanism goes through firm entry rates. A decrease in population growth lowers firm entry rates, shifting the firm-age distribution towards older firms. Heterogeneity across firm age groups combined with an aging firm distribution replicates the observed trends. Micro data show that an aging firm distribution fully explains i) the concentration of employment in large firms, ii) and trends in average firm size and exit rates, key determinants of the firm entry rate. An aging firm distribution also explains the decline in labor’s share of GDP. In our model, older firms have lower labor shares because of lower overhead labor to employment ratios. Consistent with our mechanism, we find that the ratio of nonproduction workers to total employment has declined in the US.

This article studies optimal patents with respect to the timing of innovation disclosure. In a simple model, we identify forces that lead firms to either suboptimally patent too early or too late in equilibrium, and we determine conditions so that stronger patents induce earlier or later equilibrium disclosure. Then, by solving an infinite multistage patent game with a more explicit structure, we describe innovation growth, and derive detailed predictions that can be used for policy experiments. As an application, we calibrate our multistage game using summary statistics from the seeds breeding industry. We find that weaker patent rights may result in welfare gains of 46% relative to the status quo. The gains are achieved because weaker patents reduce competition, thus leading firms to postpone patenting.

This paper studies bidding dynamics where values and bidding opportunities follow an unrestricted joint Markov process, independent across agents. Bids cannot be retracted, as is frequently the case in auctions. Our main methodological contribution is that we construct a mapping from this general stochastic process into a distribution of values that is independent of the type of auction considered. The equilibria of a static auction with this distribution of values is used to characterize the equilibria of the dynamic auction, making this general class very tractable. As a result of the option of future rebidding, early bids are shaded and under mild conditions increase toward the end of the auction. Our results are consistent with repeated bidding and skewness of the time distribution of winning bids, two puzzling observations in dynamic auctions. As an application, we estimate the model by matching moments from eBay auctions.Institutional subscribers to the NBER working paper series, and residents of developing countries may download this paper without additional charge at www.nber.org.

Models of firm microstructure are becoming now a standard building block in macroeconomics, trade, and development. This literature builds on the recognition that firm heterogeneity and the allocation of resources across firms plays a key role in determining aggregate productivity and the gains from trade. Barriers to the efficient allocation of resources across firms have been recently recognized to play a key role in economic development. This paper focuses on this methodological contribution, the link between firm microstructure and economic aggregates.

Preemption games are widely used to model economic problems such as patent races. We introduce private information into these games and allow for this information to stochastically change over time. This reflects, e.g. how R&D competitors improve their innovations over time and keep these innovations secret before patenting them. The analysis initially appears intractable because of the complexity of the equilibrium updating of beliefs on opponents' information. However, we demonstrate the existence of a class of equilibria and calculate these equilibria in closed form. We find that the expected durations in these equilibria are longer than when players' information is public but, in some cases, shorter than in the collusive outcome. Hence, R&D secrecy slows down innovation disclosure. Copyright 2011, Oxford University Press.

We study the problem of a firm that faces asymmetric information about the persistent productivity of its potential workers. In our framework, a worker's productivity is either assigned by nature at birth, or determined by an unobservable initial action of the worker that has persistent effects over time. We provide a characterization of the optimal dynamic compensation scheme that attracts only high productivity workers: consumption—regardless of time period—is ranked according to likelihood ratios of output histories, and the inverse of the marginal utility of consumption satisfies the martingale property derived in [Rogerson, William P., 1985. Repeated moral hazard. Econometrica 53 (1) 69–76]. However, in the case of i.i.d. output and square root utility we show that, contrary to the features of the optimal contract for a repeated moral hazard problem, the level and the variance of consumption are negatively correlated, due to the influence of early luck into future compensation. Moreover, in this example long-term inequality is lower under persistent private information.

In existing unemployment insurance programmes, it is standard to condition eligibility on the previous employment record of unemployed workers. The purpose of this article is to study conditions under which the efficient contract exhibits these properties. In order to do so, we characterize the optimal unemployment insurance contract in asymmetric information environments in which workers experience multiple unemployment spells. We show that if quits cannot be distinguished from layoffs, it is optimal to condition the benefits paid to unemployed workers on their employment history, in particular, the coverage should increase with the length of previous employment spells. Copyright , Wiley-Blackwell.

Entrepreneurs bear substantial risk, but empirical evidence shows no sign of a positive premium. This paper develops a theory of endogenous entrepreneurial risk taking that explains why self-financed entrepreneurs may find it optimal to invest in risky projects offering no risk premium. Consistently with empiri cal evidence, the model predicts that poorer entrepreneurs are more likely to undertake risky projects. It also finds that incentives for risk taking are stronger when agents are impatient. (JEL G31, G32, L25, L26) Entrepreneurial activity is risky and poorly diversified. Most economic models would suggest that the high degree of entrepreneurial risk should be compensated by a significant premium in returns.1 Yet empirical evidence finds that the premium to entrepreneurial activity is surprisingly low,2 which raises the question of why people become entrepreneurs. A number of hypotheses have been offered to answer this question, mostly based on the idea that entrepreneurs have a different set of preferences or beliefs (e.g., risk tolerance or overoptimism). This paper provides an alternative theory of endogenous entrepreneurial risk taking that does not rely on individual heterogeneity of preferences or beliefs. We incorporate endogenous choice of entrepreneurial risk in a simple dynamic occupational choice model. A borrowing constrained agent chooses whether to be a worker or an entrepreneur. The occupational choice is discrete, in the sense that each activity requires full-time involvement. A worker receives fixed wage income, while an entrepreneur gets access to an entrepreneurial technology and decides how much to invest in it. Borrowing constraints induce endogenous sepa ration into different occupations: the rich, who have sufficient funds for investment, choose to be entrepreneurs, and the poor prefer to receive fixed pay by becoming workers. The indivisibility of occupational choice may create a nonconcavity in the agent's value function as a function of

We analyze the problem of eliminating an inefficient regulation, such as protection, in a dynamic model in which there is incomplete information and unanimous approval from all parties involved is necessary. Existing firms have heterogeneous cost, and efficiency requires some of them to shut down when the inefficient regulation is eliminated. The government can set up a revelation mechanism, giving subsidies and requiring firms to exit the market at a given time depending on the information collected. Under full commitment the optimal policy prescribes that some inefficient firms remain active and are subsidized. The optimal policy takes a simple form, with at most two times at which the firms are allowed to exit.

There is widespread evidence supporting the conjecture that borrowing constraints have important implications for firm growth and survival. In this paper we model a multiperiod borrowing/lending relationship with asymmetric information. We show that borrowing constraints emerge as a feature of the optimal long-term lending contract, and that such constraints relax as the value of the borrower's claim to future cash flows increases. We also show that the optimal contract has interesting implications for firm dynamics. In agreement with the empirical evidence, as age and size increase, mean and variance of growth decrease, and firm survival increases.

This paper presents a model of cumulative innovation in which firms are heterogeneous in their research ability. We study the optimal reward policy when the quality of the ideas and their subsequent development effort are private information. Monopoly power is a scarce resource to be allocated across innovators who arrive at various times. The optimal assignment of property rights must counterbalance the incentives of current and future innovators. The resulting mechanism resembles a menu of patents that have infinite duration and fixed scope. This optimal patent menu can be implemented with a simple buyout scheme: The innovator commits at the outset to a price ceiling at which he will sell his rights to a future inventor. When a larger fee is paid initially, a higher price ceiling is obtained. Any subsequent innovator must pay this price and purchase his own buyout fee contract. We relate this mechanism to the proposed compulsory licensing schemes.

We develop a general model of lending in the presence of endogenous borrowing constraints. Borrowing constraints arise because borrowers face limited liability and debt repayment cannot be perfectly enforced. In the model, the dynamics of debt are closely linked with the dynamics of borrowing constraints. In fact, borrowing constraints must satisfy a dynamic consistency requirement: the value of outstanding debt restricts current access to short-term capital, but is itself determined by future access to credit. This dynamic consistency is not guaranteed in models of exogenous borrowing constraints, where the ability to raise short-term capital is limited by some prespecified function of debt. We characterize the optimal default-free contract—which minimizes borrowing constraints at all histories—and derive implications for firm growth, survival, leverage and debt maturity. The model is qualitatively consistent with stylized facts on the growth and survival of firms. Comparative statics with respect to technology and default constraints are derived. Borrowing constraints are an important determinant of firm growth and survival. 1 Such constraints may arise in connection to the financing of investment opportunities faced by firms or temporary liquidity needs, such as those required to survive a recession. This paper develops a theory of endogenous borrowing constraints and studies its implications for firm dynamics. In our model, debt is constrained by the firm’s limited liability and option to default. A lending contract specifies an initial loan size, future financing, and a repayment schedule. The choice of these variables in turn determines future growth, the firm’s future borrowing capacity, and its ability and willingness to repay. Hence, borrowing constraints and firm dynamics are jointly determined. We study this dynamic design problem. Our model builds on Thomas and Worral’s (1994) model of foreign direct investment. At time zero a risk neutral borrower (firm or entrepreneur) has a project which requires a fixed initial set-up cost. Every period the project yields revenues that increase with the amount of 1. There is considerable evidence suggesting that financing constraints are important determinants of firm dynamics. Gertler and Gilchrist (1994) argue that liquidity constraints may explain why small manufacturing firms respond more to a tightening of monetary policy than do larger manufacturing firms. Perez-Quiros and Timmermann (2000) show that in recessions smaller firms are more sensitive to the worsening of credit market conditions as measured by higher interest rates and default premia. Evans and Jovanovic (1989) show that the liquidity constraints are essential in the decision to become an entrepreneur. Fazzari, Hubbard and Petersen (1988), among others, view financial constraints as an explanation for the dynamic behaviour of aggregate investment, and Cabral and Mata (1996) are able to fit reasonably well the size distribution of Portuguese manufacturing firms by estimating a simple model of financing constraints. For surveys see Hubbard (1998) and Stein (2003).

This paper considers the question of tacit collusion in repeated auctions with independent private values and with limited public monitoring. McAfee and McMillan show that the extent of collusion is tied to the availability of transfers. Monetary transfers allow cartels to extract full surplus. A folk theorem proved by Fudenberg et al. (Econometrica 62 (1994) 997–1039) shows that transfers of future payoffs are almost as good if players are patient and communicate before auctions. We ask how the scope of collusion is affected if players dispense with explicit communication and their monitoring is limited. Collusion better than bid rotation is still feasible, but full surplus cannot be extracted. This constraint becomes less severe with more players and large cartels can become asymptotically efficient even with very limited monitoring.

After a decade of structural reforms, unemployment rates have tripled in Argentina. This paper is concerned with the measurement of unemployment risk and its distribution. We show the importance of considering re-incidence in the measurement of unemployment risk and develop a methodology to do that. Our estimates for Argentina show that, though the typical unemployment spell is short, once re-incidence is taken into account, unemployment risk is high, has risen substantially in the last decade and is shared very unequally in the labor force. This counters the established view that unemployment is a small risk, short-duration phenomenon, which arises when re-incidence is not considered.

The paper considers formally the mapping from distortions in the allocations of resources across firms to aggregate productivity. TFP gaps are characterized as the integral of a strictly concave function with respect to an employment-weighted measure of distortions. Size related distortions are shown to correspond to a mean preserving spread of this measure, explaining the stronger effects on TFP found in the literature. In general, the effect of correlation between distortions and productivity is shown to be ambiguous; conditions are given to determine its sign. An empirical lower bound on distortions based on size distribution of firms is derived and analyzed, revealing that substantial rank reversals in firm size are necessary for distortions to explain large TFP gaps. The effect of curvature on the impact and measurement of distortions is also considered.

The paper considers formally the mapping from distortions in the allocations of resources across firms to aggregate productivity. TFP gaps are characterized as the integral of a strictly concave function with respect to an employment-weighted measure of distortions. Size related distortions are shown to correspond to a mean preserving spread of this measure, explaining the stronger effects on TFP found in the literature. In general, the effect of correlation between distortions and productivity is shown to be ambiguous; conditions are given to determine its sign. An empirical lower bound on distortions based on size distribution of firms is derived and analyzed, revealing that substantial rank reversals in firm size are necessary for distortions to explain large TFP gaps. The effect of curvature on the impact and measurement of distortions is also considered.

Entry restrictions are a common form of regulation in markets and occupations, either as a means of limiting the size of a market or affecting the quality of products or services provided by it. This paper analyzes demand, cost and informational characteristics that affect the impact of this type of policies on the quality mix of products provided by an industry and the welfare of its consumers. Selective increases in the costs of entry such as licensing requirements and direct restrictions with competitive bidding for entry rights are considered. We analyze the effects of these policies on entry decisions and also the additional selection effects that are obtained when exit is allowed for and the rights to participate in an industry can be freely traded.

Firm heterogeneity and the allocation of resources across firms play a key role in determining aggregate productivity. Entry barriers and misallocation can substantially impact productivity, as evidenced in recent work. This article provides a unifying theoretical framework and a review of this literature.

We study the effect of downward wage rigidity in a dynamic model when wages are negotiated according to Nash bargaining. Downward rigidity causes a decrease in the worker’s expected utility. For the firms the effect is ambiguous. Publicado

This paper considers the design of an optimal unemployment insurance system. The problem is modeled as a repeated principalagent problem involving a risk‐averse agent‐the unemployed worker‐and a risk‐neutral principal, which cannot monitor the agent's search effort. The optimal long‐term contract subject to the associated incentive constraints is characterized. This contract involves a replacement ratio that decreases throughout the unemployment spell and a wage tax after reemployment that, under some mild regularity conditions, increases with the lenght of the unemployment spell. Some numerical results are presented that suggest that the gains from switching to this optimal unemployment insurance scheme could be quite large. The performance of this optimal contract is also compared to alternative liquidity provision mechanisms.

This paper explores the effect of policy variability (or frequency of regime switching) on economic growth and welfare. We study a one-sector growth model where investment can be subsidized at either a positive rate or not subsidized at all. We find that the lack of persistence in policies per se need not be welfare reducing and that it is likely to decrease growth. Higher variability implies more frequent changes in consumption and investment. But, by creating a stronger intertemporal link across regimes, variability reduces the fluctuation in investment rates, thus decreasing the magnitude of changes in consumption and increasing welfare.

In political settings, delegation is often motivated by differences in expertise of costs of information gathering. Even if a political principal is less well informed than a regulatory agency, she can monitor whether the agency is acting in her best interests by taking informational cues from the media, interest groups, and constituents. In response to such "fire-alarm" signals, the principal may engage in political oversight activities. This article examines how asymmetric external information flows give rise to asymmetric political control rules that introduce bias and inconsistency into regulatory outcomes. Copyright 1996 by Oxford University Press.

This paper develops a sequential random matching model of asset trading to analyze how the extent of information about an asset that is available in the market can affect its tradeability. Liquidity traders are rational agents with higher impatience, which make optimal intertemporal consumption decisions given the trading constraints. Information asymmetries result in unexecuted trades. Agents who want to consume relatively early optimally choose to exchange initial assets for new assets that have lower expected payoff but are more liquid in subsequent trading. These assets have a lower expected rate or return (i.e., a liquidity premium) and higher trading volume. Journal of Economic Literature Classification Numbers: D83, G11, G14.

Capital markets function as aggregators of private information and in an environment with imperfectly informed firms, guide investment and production decisions. We study the implications of poorly functioning capital markets for the misallocation of factors of production across heterogeneous firms. Our theoretical framework combines a noisy rational expectations model of asset markets with a standard model of production by heterogeneous firms. We use a model calibrated to cross-country stock market and firm-level data to investigate the extent to which differences in capital market conditions can explain TFP differences across countries.

Recent empirical work indicates that job creation and destruction rates are large, implying significant amounts of job reallocation across firms. This paper builds a general equilibrium model of this reallocation process, calibrates it using data on firm-level dynamics, and evaluates the aggregate implications of policies that interfere with this process. We find that a tax on job destruction at the firm level has a sizable negative impact on total employment: a tax equal to 1 year's wages reduces employment by roughly 2.5 percent. More striking, however, are the welfare consequences: the cost in terms of consumption of this same tax is greater than 2 percent. The mechanism through which this welfare loss arises is apparently a decrease in average productivity, since this policy results in a decrease in average productivity of over 2 percent.

This paper studies a competitive dynamic model with firm level uncertainty and derives implications for the distribution of firm values and Tobin's q. Allowing for entry and exit, the model determines endogenously the degree of selection. A consequence of this selection is that average industry q values are biased above one. As parameters describing the technology and firm level uncertainty are changed, the equilibrium distribution for q values changes. This comparative statics is developed in the paper.

A dynamic stochastic model for a competitive industry is developed in which entry, exit, and the growth of firms' output and employment is determined. The paper extends long-run industry equilibrium theory to account for entry, exit, and heterogeneity in the size and growth rate of firms. Conditions under which there is entry and exit in the long run are developed. Cross sectional implications and distributions of profits and value of firms are derived. Comparative statics on the equilibrium size distribution and turnover rates are analyzed. Copyright 1992 by The Econometric Society.

The authors develop a model of vintage human capital in which each technology requires vintage-specific skills. They examine the properties of a stationary equilibrium for their economy. The stationary equilibrium is characterized by an endogenous distribution of skilled workers across vintages. The distribution is shown to be single-peaked. Under general conditions, there is a lag between the appearance of a technology and its peak usage, a phenomenon known as diffusion. An increase in the rate of exogenous technological change shifts the distribution of human capital to more recent vintages, thereby increasing the diffusion rate. Copyright 1991 by University of Chicago Press.

We study a multiperiod principal-agent problem with moral hazard in which effort is persistent: the agent is required to exert effort only in the initial period of the contract, and this effort determines the conditional distribution of output in the following periods. We provide a characterization of the optimal dynamic compensation scheme. As in a static moral hazard problem, consumption — regardless of time period — is ranked according to likelihood ratios of output histories. As in most dynamic models with asymmetric information, the inverse of the marginal utility of consumption satisfies the martingale property derived in Rogerson (1985). Under the assumption of i.i.d. output we show that (i) incentives are concentrated in the later periods of the contract, implying an increase of the variance of compensation over time; (ii) the cost of implementing high effort decreases when there is an increase in either the duration or the intensity of persistence (i.e., how long and how strongly effort affects the distribution of output, respectively); and (iii) under infinite duration the cost gets arbitrarily close to that of the first best.

Entrepreneurs bear substantial risk, but empirical evidence shows no sign of a positive premium. This paper develops a theory of endogenous entrepreneurial risk taking that explains why self-financed entrepreneurs may find it optimal to invest in risky projects offering no risk premium. The model has also a number of implications for firm dynamics supported by empirical evidence, such as a positive correlation between survival, size, and firm age.

This paper characterizes the effects of market size on the size distribution of establishments for thirteen retail trade industries across 225 U.S. cities. In most industries we examine, establishments are larger in larger cities. Models of large-group competition in which markups fall after adding competitors can reproduce this observation.

THIS PAPER EXAMINES EMPIRICALLY the effects of market size on producers’ sizes in industries with many producers. A robust prediction of oligopoly theory is that larger markets are more competitive and have lower price-cost markups. Because producers in more competitive markets must recover their fixed costs by selling more at a lower markup, our estimated market size effects indicate whether or not this prediction of oligopoly theory carries over to large-group competition. Our analysis uses observations from thirteen narrowly-defined retail trade industries in 225 metropolitan statistical areas (MSAs), each of which we identify with a separate market. In all of the industries we consider, almost all of these MSAs contain a large number of establishments. Our primary data source is the 1992 Census of Retail Trade (CRT), from which we calculate establishments’ average sales and employment in each market. We supplement these measures with observations of the empirical c.d.f. of establishments’ sizes from the 1992 County Business Patterns (CBP). We regress these statistics from the size distribution against the MSA’s market size and a set of control variables. The control variables account for differences in MSAs’ factor prices and demographics, which covary with market size and can by themselves affect retailers’ sizes.

There is widespread evidence supporting the conjecture that borrowing constraints have important implications for firm growth and survival. In this paper we model a multi-period borrowing/lending relationship with asymmetric information. We show that borrowing constraints emerge as a feature of the optimal long-term lending contract, and that such constraints relax as the value of the borrower's claim to future cash-flows increases. We also show that the optimal contract has interesting implications for firm dynamics. In agreement with the empirical evidence, as age and size increase, mean and variance of growth decrease, firm survival increases, and the sensitivity of investment to cash-flows declines.

After a decade of structural reforms, unemployment rates have tripled in Argentina. This paper is concerned with the measurement of unemployment risk and its distribution. We show the importance of considering re-incidence in the measurement of unemployment risk and develop a methodolgy to do that. Our estimates for Argentina show that, though the typical unemployment spell is short, once re-incidence is taken into account, unemployment risk is high, has risen substantially in the last decade and is shared very unequally in the labor force. This counters the established view that unemployment is a small risk, short-duration phenomenon, which arises when re-incidence is not considered.

After a decade of structural reforms, unemployment rates have tripled in Argentina. This paper is concerned with the measurement of unemployment risk and its distribution. We show the importance of considering re-incidence in the measurement of risk and develop a methodology. Our estimates for Argentina show that, though the typical unemployment spell is short, once re-incidence is taken into account, unemployment risk is high, has risen substantially in the last decade and is shared very unequally in the labor force. This counters the established view that unemployment is a small risk, short-duration phenomenon, which arises when re-incidence is not considered.

Over the last few years, the debate on labor market reform has been at the center of economic policy debate in Argentina. One of the major targets of the attack on labor market regulation has been high dismissal costs. Attempts to reduce dismissal costs for all existing jobs have faced strong opposition. As a compromise, and to stimulate job creation, employment promotion contracts for new jobs were introduced in 1995. These contracts are limited to a fixed term ranging from three months to two years. There is a growing concern about the volatility of these temporary jobs, referred to as junk contracts, and a predominant view that they tend to generate excessive turnover. This paper studies the effect of this reform on job duration. The main findings are that the reform generated an overall increase in the hazard rate, and particularly so for the first three months of employment.

This paper presents a model of cumulative innovation where firms are heterogeneous in their research ability. We study the optimal reward policy when the quality of the ideas and their subsequent development effort are private information. The optimal assignment of property rights must counterbalance the incentives of current and future innovators. The resulting mechanism resembles a menu of patents that have infinite duration and fixed scope, where the latter increases in the value of the idea. Finally, we provide a way to implement this patent menu by using a simple buyout scheme: The innovator commits at the outset to a price ceiling at which he will sell his rights to a future inventor. By paying a larger fee initially, a higher price ceiling is obtained. Any subsequent innovator must pay this price and purchase its own buyout fee contract.

We develop a general model of lending in the presence of endogenous borrowing constraints. Borrowing constraints arise because borrowers face limited liability and debt repayment cannot be perfectly enforced. In the model, the dynamics of debt are closely linked with the dynamics of borrowing constraints. In fact, borrowing constraints must satisfy a dynamic consistency requirement: The value of outstanding debt restricts current access to short term capital, but is itself determined by future access to credit. This dynamic consistency is not guaranteed in models of exogenous borrowing constraints, where the ability to raise short term capital is limited by some prespecified function of debt. We characterize the optimal default-free contract - which minimizes borrowing constraints at all histories - and derive implications for firm growth, survival, leverage, and debt maturity. The model is qualitatively consistent with stylized facts on the growth and survival of firms. Comparative statics with respect to technology and default constraints are derived.

After a decade of structural reforms, unemployment rates have tripled in Argentina. This paper is concerned with the measurement of unemployment risk and its distribution. We show the importance of considering re-incidence in the measurement of risk and develop a methodology. Our estimates for Argentina show that, though the typical unemployment spell is short, once re-incidence is taken into account, unemployment risk is high, has risen substantially in the last decade and is shared very unequally in the labor force. This counters the established view that unemployment is a small risk, short-duration phenomenon, which arises when re-incidence is not considered.

It may be advantageous to provide a variety of kinds of patent protection to heterogenous innovations. Innovations which benefit society largely through their use as building blocks to future inventions may require a different scope of protection in order to be encouraged. We model the problem of designing an optimal patent menu (scope and length) when the fertility of an innovation in generating more innovations cannot be observed. The menu of patent scope can be implemented with mandated buyout fees. Evidence of heterogeneous fertility and patent obsolescence, keys to the model, are presented using patent data from the US.

It may be advantageous to provide a variety of kinds of patent protec­ tion to heterogenous innovations. Innovations which benefit society largely through their use as building blocks to future inventions may require a dif­ ferent scope of protection in order to be encouraged, since expected profits are often decreasing in a products usefulness to others when the others are competitors. We model the problem of designing an optimal patent menu when the fertility of an innovation in generating more innovations cannot be observed when the patent is granted and characterize the optimal menu when breadth is a choice variable of the patent authority. If breadth is not definable at the time of the patent due to uncertainty about the kinds of future products that will arise, the menu can still be implemented with buyout fees. Evidence of heterogeneous fertility is presented using patent data from the US.