Contributions published at Financial Economics (Thorsten Hens)

We suggest a new micro-foundation of money in which markets are well-organized but consumers' preferences are stochastic. In this model, we solve for stationary equilibria and show that there is an optimum quantity of money. The rational solution of our model is compared with actual behavior in a laboratory experiment. It turns out that the experiment gives support to our theoretical results.

This paper presents an application of evolutionary portfolio theory to stocks listed in the Swiss Market Index (SMI). We study numerically the long-run outcome of the competition of rebalancing rules for market shares in a stock market with actual dividends taken from firms listed in the SMI. Returns are endogenous because prices are determined by supply and demand stemming from the rebalancing rules. Our simulations show that in competition with rebalancing rules derived from Mean-Variance Optimization, Maximum Growth Theory and Behavioral Finance, the evolutionary portfolio rule discovered in Hens and Schenk-Hoppe (2001) will eventually hold total market wealth. According to this simple rule the portfolio weights should be proportional to the expected relative dividends of the assets.

The purpose of this book is to give a sound economic foundation of finance. Finance is a coherent branch of applied economics that is designed to understand financial markets in order to give advice for practical financial decisions. This book argues that for a sound economic foundation of finance the famous general equilibrium model which in its modern form emphasizes the incompleteness of financial markets is well suited. The aim of the book is to demonstrate that financial markets can be meaningfully embedded into a more general system of markets including, for example, commodity markets. The interaction of these markets can be described via the well known notion of a competitive equilibrium. We argue that for a sound foundation this competitive equilibrium should be unique. In a first step we demonstrate that this essential goal cannot of be achieved based only on the rationality principle, i. e. on the assumption utility maximization of some utility function subject to the budget constraint. In particular we show that this important lack of structure is disturbing as well for the case of mean-variance utility functions which are the basis of the Capital Asset Pricing Model, one of the cornerstones of finance. The final goal of our book is to give reasonable restrictions on the agents' utility functions which lead to a well determined financial markets model.

An Introduction to Wavelets and Other Filtering Methods in Finance and Economics presents a unified view of filtering techniques with a special focus on wavelet analysis in finance and economics. It emphasizes the methods and explanations of the theory that underlies them. It also concentrates on exactly what wavelet analysis (and filtering methods in general) can reveal about a time series. It offers testing issues which can be performed with wavelets in conjunction with the multi-resolution analysis. The descriptive focus of the book avoids proofs and provides easy access to a wide spectrum of parametric and nonparametric filtering methods. Examples and empirical applications will show readers the capabilities, advantages, and disadvantages of each method.

The paper investigates the effect of interest policy on price bubbles, trading behavior and portfolio choice in experimental stock markets. Anseries of experiments has 8 participants trade an asset over 15 periods. Alternatively, the participants can invest money in interest-bearing bonds. Treatment groups are subjected to an endogenous interest policy, while control groups experience a constant interest rate. Our stock markets are characterized by bubbles. While we observe a small positive impact of our interest policy on bubbles, the policy also strongly increases market volatility. On the other hand, concerning portfolio choice, we find evidencenfor value-driven (rational) investment behavior.

In the incomplete markets model with numeraire asset and a single consumption good we show that even with homothetic preferences, on compact sets of prices continuity, Walras’ identity and homogeneity characterize the properties of market excess demand. This result is proved by an extension of [J. Econ. Theory 12 (1976) 197] to the case of incomplete markets.

The paper analyzes the process of market selection of investment strategies in an incomplete asset market. The payoffs of the as-sets depend on random factors described in terms of a discrete-time Markov process. Market participants make dynamic investment de-cisions based on their observations and time. We show that a trader distributing wealth across available assets according to the relative expected returns eventually accumulates the entire market wealth. The result obtains under the assumption that the trader's strategy is asymptotically distinct from the CAPM strategy (prescribing in-vestment in the market portfolio). This assumption turns out to be essentially necessary for the conclusion.

The paper considers the evolution of portfolio rules in markets with stationary returns and endogenous prices. The ultimate success of a portfolio rule is measured by the wealth share the rule is eventually able to conquer in competition with other portfolio rules. We give necessary and sufficient conditions for portfolio rules to be evolutionary stable. In the case of i.i.d. returns we identify a simple portfolio rule to be the unique evolutionary stable strategy. Moreover we demonstrate that mean-variance optimization is not evolutionary stable while the CAPM-rule always imitates the best portfolio rule and survives.

The purpose of this paper is to explain why some markets for financial products take off while others vanish as soon as they have emerged. To this end, we model an infinite sequence of CAPM-economies in which financial products can be used for insurance purposes. Agents' participation in these financial products, however, is restricted. Consecutive stage economies are linked by a mapping (“transition function”) which determines the next period's participation structure from the preceding period's participation. The transition function generates a dynamic process of market participation which is driven by the percentage of informed traders and the rate at which a new asset is adopted. We then analyse the evolutionary stability of stationary equilibria. In accordance with the empirical literature on financial innovation, it is obtained that the success of a financial innovation, a mutation, depends on a sufficiently high trading volume, marketing, and new and differentiated hedging opportunities. In particular, a set of complete markets forming a stationary equilibrium is robust with respect to any further financial innovation while this is not necessarily true for a set of incomplete markets.

In this paper we analyze the long-run dynamics of the market selection process among simple trading strategies in an incomplete asset market with endogenous prices. We identify a unique surviving financial trading strategy. Investors following this strategy asymptotically gather total market wealth. This result generalizes findings by Blume and Easley (1992) to any complete or incomplete asset market.

The purpose of this paper is to demonstrate that in the Capital Asset Pricing Model (CAPM) the mean Slutsky-income effect is positive if on average investors have non-increasing absolute risk aversion. Together with some lower bounds on the degree to which absolute risk aversion decreases with income this result will be shown to be sufficient for the uniqueness of CAPM-equilibria.

In the incomplete markets model with numeraire asset and a single consumption good we show that, even with homothetic preferences, on compact sets of prices Continuity, Walras' identity and Homogeneity characterize the properties of market excess demand. This result is proved by an extension of Mantel (1976) to the case of incomplete markets.

"- This paper replaces the paper ""Existence and Uniqueness of Equilibria in the CAPM"" -nIn the standard CAPM with a riskless asset we give a sufficient condition for uniqueness. This condition is a joint restriction on the agents' endowments and their preferences which is compatible with non-increasing absolute risk aversion and which is in particular satisfied with constant absolute risk aversion. Moreover in the CAPM without a riskless asset we give an example for multiple equilibria even though all agents have constant absolute risk aversion."

"The purpose of this paper is to explain why some markets for financial products take off while others vanish as soon as they have emerged. To this end, we model an infinite sequence of CAPM-economies in which financial products can be used for insurance purposes. Agents' participation in these financial products, however, is restricted. Consecutive stage economies are linked by a mapping (""transition function"") which determines the next period's participation structure from the preceding period's participation. The transition function generates a dynamic process of market participation which is driven by the percentage of informed traders and the rate at which a new asset is adopted. We then analyze the evolutionary stability of stationary equilibria. In accordance with the empirical literature on financial innovation, it is obtained that the success of a financial innovation, a mutation, depends on a sufficiently high trading volume, marketing, and new and differentiated hedging opp"

This article analyses whether the representation of asset prices by Choquet integration can be justified from a general equilibrium point of view. We demonstrate that if transaction costs functionals are increasing in the volume of trade, positive homogeneous and satisfy an additivity condition, the equilibrium price functional typically does not satisfy all the Choquet properties. Whereas subadditivity and positive homogeneity can be shown to hold for the equilibrium price functional, this is generally not the case for monotonicity and additivity of prices for comonotone income streams.

The purpose of this paper is to explain empirical observations concerning the impact of exchange rate changes on industrial prices. As exchange rates change the pass-through into industrial prices is often incomplete and sometimes it goes into the "wrong" direction, i.e. the prices in the depreciating country decrease while those in the appreciating country increase. The latter is called "perverse pass-through". The usual context for such observations is one of segmented markets and imperfect competition. We consider the simplest model with these characteristics: Two duopolistic firms which both operate in two countries. The markets of the two countries are separate and each of the firms produces its good in one of these countries. We study the effect of an exchange rate change on the prices in each country and on the level of sales and of profits of each of the firms. When strong restrictions such as constant marginal costs are imposed, prices move in the "right" direction in response to an exchange rate change. However, with general cost and demand structures, even in this simple model, it is possible for prices in both countries to move in "perverse" directions.

We prove that locally, Walras' law and homogeneity characterize the structure of market excess demand functions when financial markets are incomplete and assets' returns are nominal. The method of proof is substantially different from all existing arguments as the properties of individual demand are also different. We show that this result has important implications and is part of a more general result that excess demand is an essentially arbitrary function not just of prices, but also of the exogenous parameters of the economy as asset returns, preferences, and endowments. Thus locally the equilibrium manifold, relating equilibrium prices to these parameters has also no structure.