Financial market models with Lévy processes and time-varying volatility

Asset management and pricing models require the proper modeling of the return distribution of financial assets. While the return distribution used in the traditional theories of asset pricing and portfolio selection is the normal distribution, numerous studies that have investigated the empirical behavior of asset returns in financial markets throughout the world reject the hypothesis that asset return distributions are normally distribution. Alternative models for describing return distributions have been proposed since the 1960s, with the strongest empirical and theoretical support being provided for the family of stable distributions (with the normal distribution being a special case of this distribution). Since the turn of the century, specific forms of the stable distribution have been proposed and tested that better fit the observed behavior of historical return distributions. More specifically, subclasses of the tempered stable distribution have been proposed. In this paper, we propose one such subclass of the tempered stable distribution which we refer to as the “KR distribution”. We empirically test this distribution as well as two other recently proposed subclasses of the tempered stable distribution: the Carr–Geman–Madan–Yor (CGMY) distribution and the modified tempered stable (MTS) distribution. The advantage of the KR distribution over the other two distributions is that it has more flexible tail parameters. For these three subclasses of the tempered stable distribution, which are infinitely divisible and have exponential moments for some neighborhood of zero, we generate the exponential Lévy market models induced from them. We then construct a new GARCH model with the infinitely divisible distributed innovation and three subclasses of that GARCH model that incorporates three observed properties of asset returns: volatility clustering, fat tails, and skewness. We formulate the algorithm to find the risk-neutral return processes for those GARCH models using the “change of measure” for the tempered stable distributions. To compare the performance of those exponential Lévy models and the GARCH models, we report the results of the parameters estimated for the S&P 500 index and investigate the out-of-sample forecasting performance for those GARCH models for the S&P 500 option prices.     

The optimal disposition decision for product returns

We provide an analytic model for the optimal disposition decision for product returns. The manager decides which product returns to accept for processing at the remanufacturing facility, and which ones to sell immediately as-is at a salvage value. High congestion levels in the remanufacturing facility delay the sale of the remanufactured product at the secondary market, decreasing the value at which it can be sold; this may imply a more attractive salvaging option. This is particularly important for high-tech products with short life cycles, such as computers and printers. We propose a two-step policy. In the first step, the returned product’s random processing time is observed. In the second step, a disposition decision is made: if the processing time is larger than a threshold k* the product is salvaged; otherwise the product is remanufactured. We provide an approximate procedure to compute k* in industrial settings. Our numerical study demonstrates the superiority of our policy over the current industrial practice ignoring the time value of money.     

The long-horizon returns behaviour of the Portuguese stock market1

In the last few years several research studies have challenged the traditional weak-form efficiency tests of the stock market. These studies suggested an alternative to the random walk model, containing temporary and permanent components. If stocks follow such a model then the traditional tests, using returns computed for short intervals would be unable to detect them. To investigate the evidence for such models in the Portuguese stock market ten stock indexes were created. This is a pioneer study of the Portuguese stock market, and uses nominal, real and excess returns, computed for longer horizons. Three methodologies were used: variance ratios, ordinary least squares regressions and weighted least squares regressions. The statistical significance of the results was studied using traditional parametric tests as well as non-parametric tests. The evidence is mixed, as the presence of tendencies towards mean aversion and mean reversion were detected. Results also show that the evidence is very sensitive to the methodology used and the signifcance tests performed. These results, however, do not necessarily reject the weak-form market efficiency hypothesis.     

Variances in staff-related management practices at eight European country subsidiaries of a global firm

The purpose of this study was to explore possible variances and commonalities in staff-related management practices at different country subsidiaries of the same multinational corporation (MNC). The study was exploratory, using data from ninety-six semi-structured interviews about current practices of management within eight European country subsidiaries. Results were based on 12,000 statements about management practices from staff in different countries. Analysis of the statements evidenced variances and commonalities in management practices in the country subsidiaries studied. It is suggested that variances are attributable to cultural factors, institutional pressures and other societal forces, and that commonalities might be explained by a common organizational culture. A theoretical model has been adapted to explain the conditions under which management practices take place in different country settings.     

Consequences of Economic Partnership Agreements between East and Southern African Countries and the EU for Inter- and Intra-regional Integration

Abstract

The European Union is currently negotiating Economic Partnership Agreements (EPAs) with six African, Caribbean and Pacific country groupings, aiming at establishing mutual free trade. This paper empirically assesses the impact of the EPAs on trade flows and government revenues for 22 East and Southern African countries and discusses implications for intra-regional integration. The results indicate that while moderate trade effects can be expected, relatively large budget effects are likely to occur in a number of these countries, exposing them to considerable structural and financial adjustment requirements. In addition, EPAs would strengthen the need to consolidate overlapping intra-regional integration schemes.     

Industry and time specific deviations from fundamental values in a random coefficient model

The paper analyzes the relationship between stock prices and fundamentals for a large sample of US stocks in the last 10 years using a random coefficient model. Heterogeneity and omitted variable bias are properly taken into account with model coefficients being allowed to vary across time and industries. The random coefficient model allows to track waves of reliance on analysts’ forecasts and nonfundamental stock price components across time and clearly identifies the growth of the nonfundamental component in the long 1991–2000 swing.