This paper aims to examine the potential for portfolio returns by adding together conventional and energy stocks with varying proportions. We examine the risk and return characteristics of a portfolio comprising energy and non-energy stocks from twenty countries. The period for daily data ranges from 2nd July 1999 to 2nd July 2021. We use multiscale Sharpe and VaR ratios to examine the risk and returns behaviour of a portfolio with varying composition between energy and non-energy stocks across different investment periods. Our results highlight optimal returns for the equally weighted portfolio during normal and crisis periods except COVID-19 during which more proportion of conventional stocks is preferred. Risk estimates advocate an equally weighted portfolio for all periods however risk varies with the holding period. These results carry useful investment implications during short- and long-run holdings of conventional and energy stocks in a portfolio.

Open text data, such as financial news, are thought to be able to affect or to describe stock market behavior, however, there are no widely accepted algorithms for extracting the relationship between stock quotes time series and fast-growing textual representation of economic information. The field remains challenging and understudied. In particular, topic modeling as a powerful tool for interpretable dimensionality reduction has been hardly ever used for such tasks. We present a topic modeling framework for assessing the relationship between financial news stream and stock prices in order to maximize trader\'s gain. To do so, we use a dataset of economic news sections of three Russian national media sources (Kommersant, Vedomosti, and RIA Novosti) containing 197,678 economic articles. They are used to predict 39 time series of the most liquid Russian stocks collected over eight years, from 2013 to 2021. Our approach shows the ability to detect significant return-predictive signals and outperforms 26 existing models in terms of Sharpe ratio and annual return of simple long strategy. In particular, it shows a significant Granger causal relationship for more than 70% of portfolio stocks. Furthermore, the approach produces highly interpretable results, requires no domain-specific dictionaries, and, unlike most existing industrial solutions, can be calibrated for individual time series. This makes it directly usable for trading strategies and analytical tasks. Finally, since topic modeling shows its efficiency for most European languages, our approach is expected to be transferrable to European stock markets as well.

The Sharpe ratio is a widely used risk-adjusted performance measurement in economics and finance. Most of the known statistical inferential methods devoted to the Sharpe ratio are based on the assumption that the data are normally distributed. In this article, without making any distributional assumption on the data, we develop the adjusted empirical likelihood method to obtain inference for a parameter of interest in the presence of nuisance parameters. We show that the log adjusted empirical likelihood ratio statistic is asymptotically distributed as the chi-square distribution. The proposed method is applied to obtain inference for the Sharpe ratio. Simulation results illustrate that the proposed method is comparable to Jobson and Korkie\'s method (1981) and outperforms the empirical likelihood method when the data are from a symmetric distribution. In addition, when the data are from a skewed distribution, the proposed method significantly outperforms all other existing methods. A real-data example is analyzed to exemplify the application of the proposed method.

In the context of rapid urbanization, ecosystem services (ES) losses pose serious threats to sustainability. How to assess ecological risk based on ES value (ESV) has become an urgent problem for sustainable urbanization. However, existing regional ecological risk assessment frameworks ignore important elements, such as the assessment endpoint and uncertainty, weakening their reliability and practicability. In this study, a regional ecological risk assessment framework integrating ESV and uncertainty was proposed by introducing a classical financial indicator, the Sharpe Ratio. We take Hubei Province, Central China as a case and implemented the spatially explicit risk assessment approach based on the methods of the Markov-logistic-CA model, adjusted-based equivalent factor evaluation model, and geographic information system. The results showed that the distribution of expected ecological returns and corresponding uncertainties at county level had a remarkable spatial heterogeneity, and the assessed ecological risk index in Eastern and Western Hubei was higher than that in Central Hubei, indicating that counties in Central Hubei are the priority areas for ecological risk control. Moreover, the expansion of built-up land had the most significant effect on regional ecological risk. This regional ecological risk framework can well integrate the assessment endpoint and dynamic processes of ecological risk. Our assessment framework has potential practical value for ecological risk control and land use planning on ecosystems.

Quantifying the variability in the delivery of ecosystem services across the landscape can be used to set appropriate management targets, evaluate resilience and target conservation efforts. Ecosystem functions and services may exhibit portfolio-type dynamics, whereby diversity within lower levels promotes stability at more aggregated levels. Portfolio theory provides a framework to characterize the relative performance among ecosystems and the processes that drive differences in performance. We assessed Pacific salmon Oncorhynchus spp. portfolio performance across their native latitudinal range focusing on the reliability of salmon returns as a metric with which to assess the function of salmon ecosystems and their services to humans. We used the Sharpe ratio (e.g. the size of the total salmon return to the portfolio relative to its variability (risk)) to evaluate the performance of Chinook and sockeye salmon portfolios across the west coast of North America. We evaluated the effects on portfolio performance from the variance of and covariance among salmon returns within each portfolio, and the association between portfolio performance and watershed attributes. We found a positive latitudinal trend in the risk-adjusted performance of Chinook and sockeye salmon portfolios that also correlated negatively with anthropogenic impact on watersheds (e.g. dams and land-use change). High-latitude Chinook salmon portfolios were on average 2·5 times more reliable, and their portfolio risk was mainly due to low variance in the individual assets. Sockeye salmon portfolios were also more reliable at higher latitudes, but sources of risk varied among the highest performing portfolios. Synthesis and applications. Portfolio theory provides a straightforward method for characterizing the resilience of salmon ecosystems and their services. Natural variability in portfolio performance among undeveloped watersheds provides a benchmark for restoration efforts. Locally and regionally, assessing the sources of portfolio risk can guide actions to maintain existing resilience (protect habitat and disturbance regimes that maintain response diversity; employ harvest strategies sensitive to different portfolio components) or improve restoration activities. Improving our understanding of portfolio reliability may allow for management of natural resources that is robust to ongoing environmental change. Portfolio theory provides a straightforward method for characterizing the resilience of salmon ecosystems and their services. Natural variability in portfolio performance among undeveloped watersheds provides a benchmark for restoration efforts. Locally and regionally, assessing the sources of portfolio risk can guide actions to maintain existing resilience (protect habitat and disturbance regimes that maintain response diversity; employ harvest strategies sensitive to different portfolio components) or improve restoration activities. Improving our understanding of portfolio reliability may allow for management of natural resources that is robust to ongoing environmental change.