In this paper I analyse the directed search/matching problem in an economy with heterogeneous skills and skill-biased technology. A unique symmetric equilibrium exists and is socially efficient. Matching is partially mixed in the equilibrium. A high-tech firm receives both skilled and unskilled applicants with positive probability, and favours skilled workers, while a low-tech firm receives only unskilled applicants. The model generates wage inequality among identical unskilled workers, as well as between-skill inequality, despite the fact that all unskilled workers perform the same task and have the same productivity in the two types of firms. Inequality has interesting responses to skill-biased technological progress, a general productivity slowdown, and an exogenous increase in the skill supply elasticity.

I construct a theoretical framework in which firms offer wage–tenure contracts to direct the search by risk-averse workers. All workers can search, on or off the job. I characterize an equilibrium and prove its existence. The equilibrium generates a nondegenerate, continuous distribution of employed workers over the values of contracts, despite that all matches are identical and workers observe all offers. A striking property is that the equilibrium is block recursive; that is, individuals' optimal decisions and optimal contracts are independent of the distribution of workers. This property makes the equilibrium analysis tractable. Consistent with stylized facts, the equilibrium predicts that (i) wages increase with tenure, (ii) job-to-job transitions decrease with tenure and wages, and (iii) wage mobility is limited in the sense that the lower the worker's wage, the lower the future wage a worker will move to in the next job transition. Moreover, block recursivity implies that changes in the unemployment benefit and the minimum wage have no effect on an employed worker's job-to-job transitions and contracts.

This paper extends the Kiyotaki-Wright search model of fiat money to allow for divisible money and goods. The extension allows me to examine the standard issues in monetary economics, such as the neutrality and superneutrality of money, by severing the artificial link in the Kiyotaki-Wright model between the money supply and the number of money holders. It is shown that money is neutral, but not superneutral. Money growth generates a trading opportunity effect: it changes the fraction of different agents in the economy and hence changes the probability with which agents have a successful match. In addition, money growth has a negative effect on the real money balance that is familiar in Walrasian monetary models. The balance of the two effects can imply a positive optimal money growth rate.

To answer the question in the title, this article characterizes the socially efficient organization of the market with search frictions. The efficient organization depends on the relative elasticity in the supply between the two sides of the market, the costs of participating in the market and organizing trade, and the (a)symmetry in matching. We also show that the social optimum can be implemented by a realistic market equilibrium where the organizers set up trading sites to direct the other side’s search. The results provide a unified explanation for why trade has often been organized by sellers in the goods market, by buyers (firms) in the labor market, and by both sides in the asset market. The analysis also sheds light on how the efficient market organization can change with innovations such as e-commerce and just-in-time production.

Bank loans are more available and cheaper for new and small businesses in the U.S. in concentrated banking areas than in competitive banking areas. We explain this anomaly by analyzing banks' decisions to screen projects and their competition in loan provisions. It is shown that, by exacerbating the winner's curse, an increase in the number of banks can reduce banks' screening probability by so much that the number of banks that actively compete in loan provisions falls and the expected loan rate rises. This is the case when the screening cost is low, which induces all active bidders to be informed. The opposite outcome occurs when the screening cost is high, in which case there are sufficiently many uninformed banks in bidding to attenuate the winner's curse. We also examine the social optimum.

We explain the clustering of underpricing in initial public offerings (IPOs). The model features an industry with aggregate demand uncertainty and asymmetric information about firms' quality. In the IPO market, firms can signal quality by underpricing or under-issuing new shares. Expected aggregate demand for the industry's products increases with the publicity that the industry creates through IPO underpricing. We show that asymmetric information and expectations on aggregate product demand interact with each other to generate multiple equilibria. Underpriced IPOs cluster in one equilibrium but not in the other. We use these results to explain why the clustering often occurs in particular industries, is short-lived, and is sensitive to economic conditions.

We study a labor market where workers search for jobs both on the job and off the job. In the model, there are aggregate productivity shocks and match-specific shocks. We outline the proof of existence of an equilibrium which we call a block recursive equilibrium (BRE), in which individuals' decisions and market tightness are independent of the distribution of workers over wages or contracts. A critical assumption that is responsible for a BRE to exist is that search is directed by firms' posting of contracts. We explain why a BRE does exist under the assumption of directed search and why it does not under the assumption of random search. Finally, we generalize the proof of existence of a BRE to allow workers to be ex-ante heterogeneous with respect to some observable characteristics such as education and skill. (This abstract was borrowed from another version of this item.)

We examine the labor market effects of incomplete information about the workers' own job-finding process. Search outcomes convey valuable information, and learning from search generates endogenous heterogeneity in workers' beliefs about their job-finding probability. We characterize this process and analyze its interactions with job creation and wage determination. Our theory sheds new light on how unemployment can affect workers' labor market outcomes and wage determination, providing a rational explanation for discouragement as the consequence of negative search outcomes. In particular, longer unemployment durations are likely to be followed by lower reemployment wages because a worker's beliefs about his job-finding process deteriorate with unemployment duration. Moreover, our analysis provides a set of useful results on dynamic programming with optimal learning.

The paper develops a model of directed search on the job in which transitions of workers between unemployment and employment and across employers are driven by heterogeneity in the quality of firm-worker matches. The equilibrium is such that the agents’ value and policy functions are independent of the endogenous distribution of workers across employment states. Hence, the model can be solved outside of the steady state and used to measure the effect of cyclical productivity shocks on the labor market. Productivity shocks are found to generate large fluctuations in workers’ transitions, unemployment, and vacancies when matches are experience goods, but not when matches are inspection goods.

Suppose that n buyers each want one unit and m sellers each have one or more units of a good. Sellers post prices, and then buyers choose sellers. In symmetric equilibrium, similar sellers all post one price, and buyers randomize. Hence, more or fewer buyers may arrive than a seller can accommodate. We call this frictions. We solve for prices and the endogenous matching function for finite n and m and consider the limit as n and m grow. The matching function displays decreasing returns but converges to constant returns. We argue that the standard matching function in the literature is misspecified and discuss implications for the Beveridge curve.