The Great Capitol Hill Baby Sitting Co‐op: Anecdote or Evidence for the Optimum Quantity of Money?

This paper studies a centralized market with idiosyncratic uncertainty and money as a medium of exchange from a theoretical as well as an experimental perspective. In our model, prices are fixed and markets are cleared by rationing. We prove the existence of stationary monetary equilibria and of an optimum quantity of money. The rational solution of our model, which is based on the assumption of individual rationality and rational expectations, is compared with actual behavior in a laboratory experiment. The theoretical results are strongly supported by this experiment.     

Optimal Capital Structure,Endogenous Bankruptcy,and the Term Structure of Credit Spreads

This article examines the optimal capital structure of a firm that can choose both the amount and maturity of its debt. Bankruptcy is determined endogenously rather than by the imposition of a positive net worth condition or by a cash flow constraint. The results extend Leland's (1994a) closed-form results to a much richer class of possible debt structures and permit study of the optimal maturity of debt as well as the optimal amount of debt. The model predicts leverage, credit spreads, default rates, and writedowns, which accord quite closely with historical averages. While short term debt does not exploit tax benefits as completely as long term debt, it is more likely to provide incentive compatibility between debt holders and equity holders. Short term debt reduces or eliminates “asset substitution” agency costs. The tax advantage of debt must be balanced against bankruptcy and agency costs in determining the optimal maturity of the capital structure. The model predicts differently shaped term structures of credit spreads for different levels of risk. These term structures are similar to those found empirically by Sarig and Warga (1989). Our results have important implications for bond portfolio management. In general, Macaulay duration dramatically overstates true duration of risky debt, which may be negative for “junk” bonds. Furthermore, the “convexity” of bond prices can become “concavity.”     

ECONOMIC INCENTIVES AND HOSPITALIZATION IN GERMANY

The dramatically rising health expenditures have become a matter of prime concern. Using a rich panel dataset this paper contributes to this debate by investigating factors determining the demand for hospitalization in Germany. While most previous studies have found a significant impact of social insurance on the demand for hospital trips, the empirical results presented here cast doubts on the role of those economic incentives. There are also important differences in the hospitalization behaviour of men and women, and between the full sample and those with chronic conditions, which have been neglected by the literature. © 1997 John Wiley & Sons, Ltd.     

Closed Form Solutions for Term Structure Derivatives with Log-Normal Interest Rates

We derive a unified model that gives closed form solutions for caps and floors written on interest rates as well as puts and calls written on zero-coupon bonds. The crucial assumption is that simple interest rates over a fixed finite period that matches the contract, which we want to price, are log-normally distributed. Moreover, this assumption is shown to be consistent with the Heath-Jarrow-Morton model for a specific choice of volatility.     

ESTIMATING INCENTIVE AND WELFARE EFFECTS OF NONSTATIONARY UNEMPLOYMENT BENEFITS

The distribution of unemployment duration in our equilibrium matching model with spell‐dependent unemployment benefits displays time‐varying exit rates. Building on semi‐Markov processes, we translate these rates into an expression for the aggregate unemployment rate. Structural estimation using German microdata allows us to discuss the effects of an unemployment benefit reform (Hartz IV). The reform reduced unemployment by less than 0.1 percentage points. Contrary to general beliefs, the net wage for most skill and regional groups increased. Taking the insurance effect of unemployment benefits into account, however, the reform is welfare reducing for 76% of workers.     

Options on Leveraged Equity: Theory and Empirical Tests

We develop an option pricing model for calls and puts written on leveraged equity in an economy with corporate taxes and bankruptcy costs. The model explains implied Black-Scholes volatility biases by relating them to the firm's structural characteristics such as leverage and debt covenants. We test the model by comparing predicted pricing biases with biases observed in a large cross-section of firms with liquid exchange traded option contracts. Our empirical study detects leverage related pricing biases. The magnitudes of these biases correspond to those predicted by our model. We also find significant pricing biases for firms financed primarily by short-term debt. This supports our model because short-term debt introduces net-worth hurdles similar to net-worth covenants.     

WHO SEARCHES?*

We consider a directed search model with buyers and sellers and determine whether buyers look for sellers or vice versa. The buyers and sellers can choose to search or wait; what they do in equilibrium depends on the relative size of the two populations and the price formation mechanism. We study bargaining and auctions and find that when one population is much larger than the other the former searches and the latter waits. Under auction with roughly equal populations some buyers and sellers search and some wait. Our results challenge the practice of postulating who searches and who waits.     

Stock Market Volatility and Learning

We show that consumption‐based asset pricing models with time‐separable preferences generate realistic amounts of stock price volatility if one allows for small deviations from rational expectations. Rational investors with subjective beliefs about price behavior optimally learn from past price observations. This imparts momentum and mean reversion into stock prices. The model quantitatively accounts for the volatility of returns, the volatility and persistence of the price‐dividend ratio, and the predictability of long‐horizon returns. It passes a formal statistical test for the overall fit of a set of moments provided one excludes the equity premium.