Portfolio choice,transactions costs and monopoly power

By using optimal stochastic control, where risk can be reduced by appropriate efforts, monopoly power is shown to engender reduced efforts to lower risk. It therefore gives rise to a relatively high ratio of liquid assets to net wealth. Furthermore, a decline in demand is shown to generally elicit increased efforts to reduce risk and thus yields an augmented share of risk bearing assets in the portfolio. These predictions are corroborated by invoking empirical evidence that pertains to West German industries. It thus appears that a capitalist economy is characterized by a built-in-mechanism stabilizing macroeconomic activity. This mechanism, however, is attenuated by monopoly power. That provides an additional rationale for competition policy.     

Equilibrium under price controls with endogenous transactions costs

In this paper we present an equilibrium model for an exchange economy with fixed prices and endogenously determined search or transactions costs. Given the fixed prices, endogenously determined equilibrium buying and selling prices (which include transactions costs) result. These costs occur on either the demand or supply side of each market, but not both. We see an eventual application of this approach to an evaluation of welfare costs of either economy-wide wage and price controls, or sector-specific price controls such as energy. In the final section we present some simple numerical examples which illustrate the approach.     

Currency substitution and transactions costs

This paper examines currency substitution in Canadian money demand vis-à-vis the U.S. dollar. A variant of the model developed by Bordo and Choudhri (1982) is estimated to test for the presence and extent of this substitution. The modified model is enhanced by the introduction of foreign exchange transactions costs. The resulting increased explanatory power indicates that previous tests which have omitted such costs understate the extent of currency substitution.     

Intermediaries,transport costs and interlinked transactions

Farmers in developing countries often encounter difficulties selling their products on local markets. Inadequate transport infrastructure in rural areas and large distances between areas of production and consumption mean that farmers find it costly to bring their produce to the market and this very often results in small net margins and poverty among farmers who are geographically isolated. Agriculture in developing countries is characterized by the presence of intermediaries that have a cost advantage over farmers. Because of their market power, these intermediaries are able to impose interlinked contracts and are free to choose the spatial pricing policy they use. In this paper, we develop a model of input–output interlinked contracts between an intermediary and geographically dispersed farmers. We establish when the intermediary uses either uniform or mill pricing policies, as opposed to spatial discriminatory pricing. For each pricing policy, we analyze what the welfare implications are in terms of an increase in farmers' income and a reduction in poverty in rural areas. We also establish how the choice of a spatial pricing policy impacts geographically isolated farmers and how it influences the participation by farmers.     

Equity and adverse selection with correlated costs

We show that agent concern with inequity is not constraining for a principal when the binary costs of two risk neutral agents are correlated.     

Portfolio selection by Austrian insurance companies

Zusammenfassung Ausgehend von einem modifizierten Modell vonParkin (1970) wird versucht, das Anlageverhalten der österreichischen Vertragsversicherungen ökonometrisch zu erfassen. In diesem Modell wird das gewünschte Portefeuille abhängig von den erwarteten Ertragsraten der einzelnen Aktiva gemacht. Um diesen Ansatz auf Daten anwenden zu können, sind Annahmen über den Zusammenhang von tatsächlichem und gewünschtem Portefeuille sowie über die Erwartungsbildung notwendig. In dieser Arbeit wurden der Stockanpassungsmechanismus und der marginale Anpassungsmechanismus sowie unitäre und rationale Erwartungen näher untersucht.Die Anwendung dieser Modelle auf Daten der österreichischen Versicherungswirtschaft im Zeitraum 1973 bis 1982 zeigt, daß der marginale Anpassungsmechanismus besser geeignet ist, die Enge der heimischen Finanzmärkte wiederzugeben, und daß unitäre Erwartungen rationalen vorzuziehen sind. Im Gegensatz zu Wertpapieren und Forderungen, die zueinander Substitute sind, herrscht bei den Einlagen das Transaktionsmotiv vor, sodaß für diese Position das Portfoliomodell wenig geeignet erscheint. Es ist jedoch nicht auszuschließen, daß die Ergebnisse stark von institutionellen Gegebenheiten beeinflußt worden sind.

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The author is indebted to G. Winckler for helpful discussions.     

Portfolio selection in a lognormal securities market

Conclusion This paper, therefore, once again establishes the usefulness of the two parameter distributions in the analysis of portfolio selection and taxation. Assuming a lognormal securities market and a chance-constrained portfolio choice model, we derive the well known results of portfolio separation and the effects of taxation which were earlier obtained under more restrictive mean-variance assumptions.This paper, an earlier version of which was presented at the 8th International Symposium on Mathematical Programming, Stanford University, August 27–31, 1973, is based on a chapter of the author's Ph. D. thesis (Ahsan, 1974). The author is grateful to S. Ahmad, A. B. Atkinson, C. J. Bliss, D. W. Butterfield, A. L. Robb, T. Russell and W. M. Scarth for helpful comments.     

Portfolio selection based on predictive joint return distribution

A predictive joint return distribution can provide more useful information than moment-based risk measures in portfolio selection. This article develops a D-vine copula-CAViaR method to estimate and predict the joint probability distribution of multiple financial returns. Furthermore, we construct a portfolio model via the generalized Omega ratio inferred from the predicted joint return distribution. The superiority of our method is illustrated through an empirical application on five international stock market indices.     

Search costs and the severity of adverse selection

In view of some recent empirical evidence, I suggest a relationship between the magnitude of search costs and the severity of adverse selection in the context of a dynamic model with asymmetric information. In markets with small search costs sellers with low quality products misrepresent their quality and demand a high price. If search costs are not negligible, sellers׳ price offers are truthful and all product qualities are traded over time. In markets with small search costs, a budget balanced mechanism can mitigate adverse selection: sellers should pay a per period market participation tax and receive a rebate after trading.     

Exit, sunk costs and the selection of firms

Summary. This paper aims to identify the cost characteristics of exiting firms whenever firms are playing an infinite horizon supergame with time-invariant cost and demand functions. With more than two firms, the problem of which firms exit is quite similar to a coalition formation one. Solving this coalition formation problem, we obtain that the exiting firms are those with higher average cost functions whenever reentry is costless while, whenever reentry is unprofitable, the exiting firms are those with lower marginal (and possibly average) cost functions. Since reentry costs are typically sunk, our analysis points out that the presence of sunk costs affects not only the size (as it is well known) but also the composition of the industry. Received: April 5, 1995; revised version: January 28, 1998     

Adaptive Portfolio Allocation with Options

We conducted a laboratory experiment of repeated portfolio allocation choice between a bond, a stock, and a put option on the stock. The study involves two conditions: a full hedging possibility and a partial hedging possibility. Surprisingly, participants were able to converge to the mean-variance frontier in the environment with partial hedging possibilities, but were unable to do so in the full hedging condition. This suggests that subjects may not be cognizant of the mean-variance frontier. If subjects begin away from the frontier and have to adjust toward it, incentives off the frontier are critical. Simulations of adaptive dynamic models confirm this assertion. The study provides insight into the adaptive behavior of investors in the presence of hedging possibilities and implications for efficient investment strategies.     

Portfolio management with tail dependence

Many publications, that treated with Portfolio Management, were devastating for all asset allocation models in the context of portfolios. The elimination of extreme events (asymmetric or tail dependence) during the portfolio construction process can reduce the skills of asset managers to reduce risk through diversification. The copula theory allows us to calculate an alternative to measure the dependence of extreme events in assets through the index lower tail dependence. We check that the strategies with tail dependence overcame Talmud rule, the Markowitz model and the model of Tu and Zhou by simulating 1,000 portfolios with 3, 5, 10 and 20 randomly selected assets from DJIA for the period 03/1990 until 12/2016. We conclude that models of tail dependence and Markowitz had more performance ex-ante than Talmud and the Tu and Zhou model for portfolios with 3, 5, 10 and 20 assets. Tail dependence models overcome Markowitz, in terms of cumulative return, in over 60% of months considered in the analysis. The results indicate that the Talmud rule should be discarded in a context of constructing portfolios with individual stocks ahead strategies with tail dependence.     

Leniency policies and illegal transactions

We study the consequences of leniency—reduced legal sanctions for wrongdoers who spontaneously self-report to law enforcers—on sequential, bilateral, illegal transactions, such as corruption, manager–auditor collusion, or drug deals. It is known that leniency helps deterring illegal relationships sustained by repeated interaction. Here we find that—when not properly designed—leniency may simultaneously provide an effective governance mechanism for occasional sequential illegal transactions that would not be feasible in its absence.     

Portfolio Fishing

The optimal fishing pattern in a multi-cohort fishery is determined using risk theory.Portfolio theory becomes applicable by treating different age groups of fish as different assets. A possibility set is derived using data on Icelandic cod fisheries. In the presence of risk aversion, it is shown that the abrupt behavior found in deterministic models is changed towards a smoother fishing pattern. The historical selection pattern for the Icelandic cod stock is shown to be near optimal using a maximal effort-type cost function, but historical levels of effort are inefficient and lead to less profit and greater fluctuations than implied by profit or utility maximization.     

Persuasion with communication costs

This paper studies strategic transmission of verifiable information with reporting costs that continuously increase in the precision of the report. Contrary to previous literature, it is shown that the unraveling result first derived by Milgrom (1981) is relatively robust to costly reporting. A separating equilibrium exists even with arbitrarily high reporting costs. Intuitively, the costs work as a signaling device and a combination of disclosure of information and costly signaling accomplishes full separation. With reporting costs there are typically multiple equilibria. For example, a pooling equilibrium exists if and only if the reporting costs are high. Finally, a separating equilibrium exists when the receiver has to make a costly effort in order to access the information in a report, as long as this cost is not too high.     

Bargaining with revoking costs

A simple two stage bilateral bargaining game is analyzed. The players simultaneously demand shares of a unit size pie. If the demands add up to more than one, the players simultaneously choose whether to stick to their demand or accept the other?s offer. While both parties sticking to their offers leads to an impasse, accepting a lower share than the original demand is costly for each party. The set of pure strategy subgame perfect equilibria of the game is characterized for continuously differentiable payoff and cost functions, strictly increasing in the pie share and the amount conceded, respectively. Higher cost functions are shown to improve bargaining power. The limit equilibrium prediction of the model, as the cost functions are made arbitrarily high, selects a unique equilibrium in the Nash Demand Game that corresponds to a Proportional Bargaining Solution of Kalai (1977).     

A theory of interlinked rural transactions

This paper argues that a landlord/owner-cultivator who is unable to monitor a tent/laborer's effort input will link a wage-cum-output sharing contract with the provision of consumption credit. The response of contractual parameters to (a) alternative opportunities available to tenant/laborers, (b) the cost of credit, and (c) the riskiness of cultivation is then examined. The analysis shows that public policy designed to alleviate rural poverty must recognize the delicate relationships between technological considerations (prohibitive monitoring costs) and modes of transaction (interlinked contracts) that arise in the absence of a complete set of markets.