Ronald Huisman

Tail-Index Estimates in Small Samples

Financial returns are known to be nonnormal and tend to have fat-tailed distributions. This article presents a simple methodology that accurately estimates the degree of tail fatness, characterized by the tail index, in small samples. Our method is a weighted average of Hill estimators for different threshold values that corrects for the small-sample bias apparent in the latter. Using this estimator we produce tail-index estimates for returns on exchange rates that are close to nonbiased estimates obtained from extremely large datasets. The results indicate that many documented conclusions concerning the tail behavior of financial series are likely to have overestimated the tail fatness in small samples.

Optimal portfolio selection in a Value-at-Risk framework

Abstract In this paper, we develop a portfolio selection model which allocates financial assets by maximising expected return subject to the constraint that the expected maximum loss should meet the Value-at-Risk limits set by the risk manager. Similar to the mean–variance approach a performance index like the Sharpe index is constructed. Furthermore when expected returns are assumed to be normally distributed we show that the model provides almost identical results to the mean–variance approach. We provide an empirical analysis using two risky assets: US stocks and bonds. The results highlight the influence of both non-normal characteristics of the expected return distribution and the length of investment time horizon on the optimal portfolio selection.

Continental factors in international real estate returns

This paper examines the extent to which real estate returns are driven by continental factors. This subject is relevant for determining the country allocation of international real estate portfolios. If returns are driven by a continental factor, investors should look for diversification opportunities outside their own continent. This paper finds strong continental factors in North America and especially in the United States. For the Asia–Pacific region, real estate returns are not driven by a continental factor. The results suggest that, for European, North American and Asia—Pacific real estate portfolio managers, the Asia—Pacific region provides attractive international diversification opportunities.

Extreme support for uncovered interest parity

Abstract Concerning UIP, the common conclusion is that it may be valid but undetectable for many reasons. In this paper we take a complementary route in that we base our methodology on a random time effects panel model that controls for various biasing factors and which is invariant to the choice of the numeraire currency. We show that the rejection of UIP is not as severe as is commonly found and that it almost perfectly holds in periods where the forward premiums are large.

VaR-x: fat tails in financial risk management

To ensure a competent regulatory framework with respect to Value-at-Risk for Establishing Banks capital adequacy requirements, as promoted by the Basle Committee, then the parametrical approach to estimate VaR needs to incorporte fat tails, apparent in the return distributions of financial assets. This paper provides a simple method to obtain accurate parametric VaR-x mesures, by including a specific measure for the tail fatness of an assets return distribution.

The influence of temperature on spike probability in day-ahead power prices

It is well known that day-ahead prices in power markets exhibit spikes and time-varying volatility. Spikes and extremely high volatility are the results of (short-term) frictions in demand and/or supply conditions. It is known that information on load or the reserve margin help to forecast spikes. However, these variables are not (timely) available for every market participant and this paper suggests to use temperature as a proxy. Interpreting the results from several switching-regimes models, the paper shows that the probability of spike occurrence increases when temperature deviates substantially from mean temperature levels.

Hourly Electricity Prices in Day-ahead Markets

This paper focuses on the characteristics of hourly electricity prices in day-ahead markets. In these markets, quotes for day-ahead delivery of electricity are submitted simultaneously for all hours in the next day. The same information set is used for quoting all hours of the day. The dynamics of hourly electricity prices does not behave as a time series process. Instead, these prices should be treated as a panel in which the prices of 24 cross-sectional hours vary from day to day. This paper introduces a panel model for hourly electricity prices in day-ahead markets and examines their characteristics. The results show that hourly electricity prices exhibit hourly specific mean-reversion and that they oscillate around an hourly specific mean price level. Furthermore, a block structured cross-sectional correlation pattern between the hours is apparent.

A history of European electricity day-ahead prices

In this article, we examine the development of day-ahead prices in five European markets which became more connected over recent years. Where previous studies examined the convergence of price levels over time, we focus on patterns in estimates for the parameters in a switching regimes model. This makes it possible to distinguish between prices under normal market conditions and under non-normal market conditions, those market conditions that can cause extreme price spikes. We expect that increased connectivity yields additional supply in the short-term and therefore will reduce the impact of price spikes. Our results indicate that the impact of price spikes and volatility decreased over time, that prices behave more random, and that the parameter estimates between various connected markets seem to have converged between the Belgian, Dutch, French, German and Nordic day-ahead markets over the years 2003 through 2010. These results can be explained by increased connectivity and improved liquidity.

The tail fatness of FX returns reconsidered

: Franz C. Palm, Faculty of Economics and Business Administration, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands. Telephone: +31-43-3883833; Fax: +31-43-3884874; e-mail: F.Palm @KE.unimaas.nl. Ronald Huisman is affiliated with Erasmus University, Rotterdam; Kees Koedijk is at Erasmus University, Rotterdam, and at Maastricht University; Clemens Kool and Franz Palm are both at Maastricht University. The authors would like to thank seminar participants at Maastricht University for their helpful comments. All remaining errors pertain to the authors.

Renewable energy and electricity prices: indirect empirical evidence from hydro power

Many countries have introduced policies to stimulate the production of electricity in a sustainable or renewable way. Theoretical and simulation studies provide evidence that the introduction of renewable energy promotion policies lead to lower electricity prices as sustainable energy supply as wind and solar have very low or even zero marginal costs. Empirical support for this result is relatively scarce. The motivation for this study is to provide additional empirical evidence on how the growth of low marginal costs renewable energy supply such as wind and solar influences power prices. We do so indirectly studying Nord Pool market prices where hydro power is the dominant supply source. We argue that the marginal costs of hydro production varies depending on reservoir levels that determine hydro production capacity. Hydro power producers have an option to produce or to delay production and the value of the option to delay increases when the reservoir levels decrease and the option to delay decreases in value when reservoir levels increase and producers face the risk of spillovers. Hence, an increase in reservoir levels mimics the situation of an increase of low marginal costs renewable energy in a market. Our results show that higher reservoir levels, more hydro capacity, lead to significant lower power prices. From this we conclude that an increase in low marginal costs renewable power supply reduces the power prices. The second contribution of this paper is that we develop a market clearing price model by modelling the supply curve of power that varies over time depending on fundamentals such as hydro capacity and the prices of alternative power sources and that deals with maximum prices which apply to all power markets that we know. With our result, we strengthen support for the view that an increase in wind and solar supply lowers the power price. This is good news for consumers, but it increases the costs of sustainable energy policies such as feed-in tariffs and at the same time lowers revenues and profits for power producers in case governments would abandon such policies. This effect makes the economic and policy support for renewable energy less sustainable. Policy makers have to account for this if they want to stimulate a sustainable growth of sustainable energy supply.