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.

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 empirical 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.

In the U.S., large firms now account for a greater share of economic activity, new firms are being created at slower rates, and workers are receiving a smaller share of GDP. Changes in population growth provide a unified quantitative explanation. A decrease in population growth lowers firm entry rates, shifting the firm‐age distribution toward older firms. Firm aging accounts for (i) the concentration of employment in large firms, (ii) and trends in average firm size and exit rates, key determinants of firm entry rates. Feedback effects from firm demographics generate two‐thirds of the effect. Prior to the decrease, entry rates rose steadily reflecting the earlier baby boom. The glut of firms due to the baby boom lead to rich transitional dynamics within the feedback effects, accounting for more than half the total change. Baby boom induced changes in the firm‐age distribution provide a driving force for the post‐WWII rise and fall in the aggregate labor share. Ignoring changes in population growth attributes all the long run decline in entry rates to a decrease in firm exit rates, which in reality have been only one‐third as large.

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.

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.

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.

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 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.