Beating the market? A mathematical puzzle for market efficiency

The efficient market hypothesis is highly discussed in economic literature. In its strongest form, it states that there are no price trends. When weakening the non-trending assumption to arbitrary short, small, and fully unknown trends, we mathematically prove for a specific class of control-based trading strategies positive expected gains. These strategies are model free, i.e., a trader neither has to think about predictable patterns nor has to estimate market parameters such as the trend’s sign like momentum traders have to do. That means, since the trader does not have to know any trend, even trends too small to find are enough to beat the market. Adjustments for risk and comparisons with buy-and-hold strategies do not satisfactorily solve the problem. In detail, we generalize results from the literature on control-based trading strategies to market settings without specific model assumptions, but with time-varying parameters in discrete and continuous time. We give closed-form formulae for the expected gain as well as the gain’s variance and generalize control-based trading rules to a setting where older information counts less. In addition, we perform an exemplary backtesting study taking transaction costs and bid-ask spreads into account and still observe—on average—positive gains.

     

The impact of risk-based regulation on European insurers’ investment strategy

This paper examines the impact of Solvency II on the attainability of target returns, the attainability of portfolio efficiency and the asset allocation of European insurers. I start with a brief introduction to the Solvency II Directive, focusing on the rules for calculating solvency capital requirements (SCR) according to the Solvency II standard formula. The subsequent numerical analysis includes several portfolio optimizations focusing on six relevant asset classes for the 1993–2017 time period. I derive optimal portfolios with respect to the Solvency II capital requirements, with respect to conventional risk measures, and I combine both optimization problems. My results show that the capital requirements according to Solvency II are not adequately calibrated. Nevertheless, due to a solid equity base, the majority of European insurers are still able to attain high target returns and mean-variance-efficiency. However, undercapitalized insurers are not able to hold risk-optimal allocations of equities, real estate and hedge funds any longer. In an environment of very low interest rates, these insurers may also face difficulties obtaining their target returns. To the best of my knowledge, this is the first paper to explicitly incorporate the solvency capital requirement as a numerical constraint into the insurers’ portfolio optimization problem. As a result, my approach first provides insights about the attainable target return and the asset weights as a direct function of insurers’ equity.     

Where are the rent seekers?

In a remarkably simple and yet one of the most original and insightful observations of 20th century economics, Gordon Tullock pointed out that there are efficiency losses when public policies and political behavior create contestable rents. Tullock also observed that social losses from contesting rents appeared smaller than might be expected, so raising the question ‘where are the rent seekers?’ Tullock proposed that political accountability and ‘free-riding’ incentives in interest groups limit social losses from rent seeking. We affirm Tullock’s explanations, which apply differently under different political institutions. We compare Tullock with Gary Becker, who focused on deadweight losses from redistribution and concluded, in contrast to Tullock, that political redistribution is efficient. The comparison with Becker highlights the significance of the recognition of Tullock’s concept of rent seeking. By excluding rent-seeking losses from the social costs of redistribution, Becker could arrive at a conclusion more favorable than Tullock to an ideology that sees merit in extensive redistribution. Tullock’s model, although more encompassing of actual social costs of redistribution, would have been less welcome in the social democratic welfare state.     

The Rate of Change in Evolutionary Systems and Evolutionary Economic Modeling

Evolutionary economics seeks to model socio-economic reality as an evolutionary system. This powerful approach entails the implication of the continuous loss of information through the evolutionary process. The implication corresponds to evolutionary biology, although the systems in evolutionary economics are different from those in evolutionary biology. The issue of the loss of information has not been extensively studied in economics. Many open questions remain: Which knowledge is lost under what circumstances? Can loss of information be harmful to the socio-economic system as a whole in the presence of runaway dynamics caused by, for example, network externalities? How can the development of knowledge in economic systems be studied? The present article examines these questions and more.     

Parameter estimation for a bivariate lifetime distribution in reliability with multivariate extensions

Bivariate lifetime distributions are considered which describe physically motivated dependencies like those proposed by Freund (1961) and Marshall and Olkin (1967a). Such distributions arise in reliability problems with two-component systems. Generalizations of some previous models are investigated and the maximum likelihood estimates for a combined bivariate exponential distribution are given. The case of dependent random censorship is considered in connection with two-component series systems. Some simulations show how censorship affects the parameter estimates.     

Cross-Sectional Profitability of Namibian Formal Small-Scale Mining Firms in 1990

Namibia considers formal small-scale mining firms (FSSMFs) as an important part of the solution to the problems of high unemployment, poverty, and the diminishing role of large-scale mining firms facing the country. However, to be a solution FSSMFs must be profitable first. This paper examines and presents simple estimates and tests of the probability of 25 Namibian SSMFs being profitable. The results suggest that in terms of productivity, specialization, size and structure, small is not as beautiful as generally presented. The findings recommend capital formation and competitive diversification of production and products.