Limits of Arbitrage: Theory and Evidence from the Mortgage-Backed Securities Market

“Limits of Arbitrage” theories hypothesize that the marginal investor in a particular asset market is a specialized arbitrageur rather than a diversified representative investor. We examine the mortgage‐backed securities (MBS) market in this light. We show that the risk of homeowner prepayment, which is a wash in the aggregate, is priced in the MBS market. The covariance of prepayment risk with aggregate wealth implies the wrong sign to match the observed prices of prepayment risk. The price of risk is better explained by a kernel based on MBS market‐wide specific risk, consistent with the specialized arbitrageur hypothesis.     

Real Wage Rigidities and the New Keynesian Model

Most central banks perceive a trade‐off between stabilizing inflation and stabilizing the gap between output and desired output. However, the standard new Keynesian framework implies no such trade‐off. In that framework, stabilizing inflation is equivalent to stabilizing the welfare‐relevant output gap. In this paper, we argue that this property of the new Keynesian framework, which we call the divine coincidence, is due to a special feature of the model: the absence of nontrivial real imperfections. We focus on one such real imperfection, namely, real wage rigidities. When the baseline new Keynesian model is extended to allow for real wage rigidities, the divine coincidence disappears, and central banks indeed face a trade‐off between stabilizing inflation and stabilizing the welfare‐relevant output gap. We show that not only does the extended model have more realistic normative implications, but it also has appealing positive properties. In particular, it provides a natural interpretation for the dynamic inflation–unemployment relation found in the data.     

International Environmental Agreements under Endogenous Uncertainty

This paper explores the implications of the possibility of a shift in environmental damages on the participation in environmental treaties. Using a two‐period model where the probability of a regime shift increases in the first‐period pollution stock, we examine the issue of coalition formation under both fixed and dynamic membership. Our analysis suggests that endogenous uncertainty may increase participation. We find that full cooperation may be sustained, but only in the presence of endogenous uncertainty. Interestingly, when the shift in the environmental damage is large enough, the model provides a way to solve the “puzzle of small coalitions” found in the literature related to international environmental agreements. We also find that in period 1 (period 2) endogenous uncertainty leads to a lower (higher) pollution stock under dynamic membership as compared to the fixed membership case.     

The Distribution of Daily Stock Returns and Settlement Procedures: The Paris Bourse

In many countries settlements take place a fixed number of business days after the transaction (U.S., Japan). In other countries settlements take place periodically on a fixed date when all transactions performed before this date are settled (U.K., France, Italy). In both cases settlement procedures should cause returns not to be identically distributed over all days. The effect is likely to be the largest on markets where all trades are settled only once a month. An empirical investigation of the largest of those markets, the Paris Bourse, demonstrates the importance of the settlement procedure on the distribution of daily returns.     

The Relation between Stock Prices and Inflationary Expectations: The International Evidence

This paper provides empirical evidence on the relation between stock returns and inflationary expectations for nine countries over the period 1971–80. The Fisherian assumption that real returns are independent of inflationary expectations is soundly rejected for each major stock market of the world. Using interest rates as a proxy for expected inflation, our data provide consistent support for the Geske and Roll model whose basic hypothesis is that stock price movements signal (negative) revisions in inflationary expectations. Finally, a weak real interest rate effect was found for some of these countries.     

Unemployment Compensation and the Allocation of Labor in Developing Countries

This paper studies the effects of the introduction of unemployment compensation (UC) in countries characterized by pervasive informality. We provide a simple framework to analyze the impact of UC on the allocation of workers between formal and informal activities, as well as the allocation of workers between sectors featuring different incentives to go informal. We show that a reasonable amount of UC may reduce informality, while larger amounts of UC induce large disincentives to go formal because of the level of taxation involved. We also argue that the financing of UC should be part and parcel of a well‐conceived UC system. We show that UC finance based on payroll taxes is likely to entail an excess level of informality resulting from cross‐subsidies between heterogenous sectors. The introduction of a simple layoff tax meant to finance the UC system is then shown to reduce informality, hence highlighting how a well‐designed financing scheme may be used as a supplementary instrument to curb informality.     

Observing and Shaping the Market: The Dilemma of Central Banks

While the central bank observes market activity to assess economic fundamentals, it shapes the market outcome through the conduct of monetary policy. A dilemma arises from this dual role because the more the central bank shapes the market, the more it influences the informational content of market outcomes. This paper analyzes how accounting for the endogeneity of information affects optimal monetary policy. By reducing the accuracy of central bank information, endogenous information calls for a higher degree of opacity, weakens accommodation policy to shocks, and broadens the range of parameters for which taking a signaling action is detrimental to welfare.