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This paper develops an empirical approach to evaluate network-based portfolio strategies relative to traditional benchmarks in the Casablanca Stock Exchange. Using the Moroccan All Shares Index, daily closing prices are used to compute historical log-returns. A rolling-window backtesting procedure over 2013–2022 ensures robustness across market regimes. Time-varying dependencies are estimated with the dynamic conditional correlation generalized autoregressive conditional heteroskedasticity (GARCH) model, capturing evolving correlations. These correlation matrices are filtered through the triangulated maximally filtered graph (TMFG) and minimum spanning tree (MST) to construct financial networks. Centrality measures identify systemically important and peripheral stocks, forming nine portfolio strategies, including TMFG- and MST-based selections, ESG-integrated portfolios and classical benchmarks such as minimum-variance (MVP) and equal-weighted portfolios. Performance is evaluated using Sharpe ratio, Sortino ratio, maximum drawdown and cumulative returns. Results indicate that the MVP provides downside protection but underperforms in bullish markets, whereas network-based strategies, particularly the TMFG selection portfolio, show consistent outperformance. ESG portfolios yield solid returns but with higher volatility, highlighting the need for risk control. Integrating network topology with dynamic correlation estimation enhances portfolio resilience in emerging markets, offering practical insights for investors and regulators.

The emerging new energy vehicles (NEV) industry is strategically important for China. How to capture its operating characteristics is a challenging but meaningful work. Considering that physical network (e.g. buyer–supplier) or correlation network (e.g. financial contagion) can provide the effective market information for enterprises in the operations management, we first construct the stock returns-based tail dependence network of the NEV industry by combining the Delta conditional value-at-risk (CoVaR) measure and the triangulated maximally filtered graph (TMFG) algorithm. We then explore the topological structure of the constructed network and obtain the operating characteristics for each enterprise in the whole industrial supply chain and at different levels. The empirical results show that the dependence and influence of different enterprises in the whole industrial supply chain are heterogeneous. In particular, upstream enterprises have closer dependence and faster influence power at all levels. These findings from the NEV industry with 71 listed enterprises would not only help regulators identify enterprises that affect the industry stability, but also help investors reduce risk across different enterprises, and managers can adjust operation strategies to reduce operating risks. On the theoretical side, we extend the network theory to the NEV industry. On the practical side, it is the first to capture the operating characteristics of the NEV industry in mainland China. In addition, on the methodological side, it constructs a new TMFG-CoVaR network.

PurposeThis study aims to explore the dependence structure among Chinese firms across the emerging 5G industry at different stages and to provide some strategic insights for market participants.Design/methodology/approachThis study adopt macroeconomic fundamentals and the log-returns of 45 listed firms in the Chinese 5G industry to construct the weighted adjacency matrix by measuring the correlation parameters and then use the triangulated maximally filtered graph (TMFG) algorithm to construct the dependence network. It analyses the topological structure of the constructed networks to obtain the dependence characteristics for each firm in the whole industrial supply chain at different levels.FindingsThe empirical results provide a comprehensive and concise snapshot of the industrial structure, across the whole 5G industry at different levels, rather than just a “one-to-one” pattern. Specifically, the dependence characteristics of different firms are heterogeneous, and most firms are highly connected with partners in the whole industrial supply chain, whereas a few firms that are weakly connected. Those closely connected firms are usually in the midstream. In addition, compared with firms at different levels, downstream firms usually have closer dependencies and stronger influence capabilities.Practical implicationsRegulators not only should promote stability development for those firms most intensely connected with whole industry chain but also protect those firms with weak link in the whole industry chain. Investors should better understand the embedded ties among different firms to obtain effective market information and can select multiple firms with fewer connections as backup to conduct joint investment for risk mitigation. Mangers should give priority to the central players/firms in the whole industrial supply chain and establish the alliances with closely connected firms.Originality/valueThis study contributes to both the information system and operation management literature by constructing a new network method, Copula-TMFG, to capture the dependence structure among Chinese firms in 5G industry, empirically providing some strategic insights for 5G industry stakeholders, such as regulators, investors and managers.

The stock market is characterized by its high nonlinearity and complexity, making traditional methods ineffective in capturing its nonlinear features and complex market dynamics. This paper proposes a novel stock price forecasting model—the Variational Mode Decomposition—Triangulated Maximally Filtered Graph—Long Short-Term Memory (VMD–TMFG–LSTM) combined model—aimed at improving prediction accuracy, stability, and computational efficiency. The proposed model first employs Variational Mode Decomposition (VMD) to decompose the stock price time series into multiple smooth intrinsic mode functions (IMFs), reducing data complexity and mitigating noise interference. Subsequently, the TMFG algorithm is utilized for feature selection, simplifying the input data and accelerating the iterative convergence process. Finally, the filtered features are modeled and predicted using a Long Short-Term Memory (LSTM) network. Experimental results demonstrate that the VMD–TMFG–LSTM model significantly outperforms AutoRegressive Integrated Moving Average (ARIMA), Neural Network (NN), Deep Neural Network (DNN), Convolutional Neural Network (CNN), as well as single LSTM, TMFG–LSTM, and VMD–LSTM models in forecasting the closing prices of multiple stocks. Specifically, for Shanghai International Airport Co., Ltd. (sh600009), the VMD–TMFG–LSTM model achieves a 69.76% reduction in Root Mean Squared Error (RMSE), a 71.41% reduction in Mean Absolute Error (MAE), a 46.28% reduction in runtime, and an improvement of 0.2184 in R-squared (R 2 ), indicating significantly higher prediction accuracy. In conclusion, the combined model proposed in this paper enhances the accuracy, efficiency, and stability of stock price prediction, providing a robust and efficient solution for forecasting stock market trends.

Information filtering networks (IFNs) provide a powerful framework for modeling complex systems through globally sparse yet locally dense and interpretable structures that capture multivariate dependencies. This review offers a comprehensive account of IFNs, covering their theoretical foundations, construction methodologies, and diverse applications. Tracing their origins from early network-based models to advanced formulations such as the triangulated maximally filtered graph and the maximally filtered clique forest, the paper highlights how IFNs address key challenges in high-dimensional data-driven modeling. IFNs and their construction methodologies are intrinsically higher-order networks that generate simplicial complexes-structures that are only now becoming popular in the broader literature. Applications span fields including finance, biology, psychology, and artificial intelligence, where IFNs improve interpretability, computational efficiency, and predictive performance. Special attention is given to their role in graphical modeling, where IFNs enable the estimation of sparse inverse covariance matrices with greater accuracy and scalability than traditional approaches like Graphical LASSO. Finally, the review discusses recent developments that integrate IFNs with machine learning and deep learning, underscoring their potential not only to bridge classical network theory with contemporary data-driven paradigms, but also to shape the architectures of deep learning models themselves.

Portfolio optimization approaches inevitably rely on multivariate modeling of markets and the economy. In this paper, we address three sources of error related to the modeling of these complex systems: 1. oversimplifying hypothesis; 2. uncertainties resulting from parameters’ sampling error; 3. intrinsic non-stationarity of these systems. For what concerns point 1. we propose a L0-norm sparse elliptical modeling and show thatsparsification is effective. We quantify the effects of points 2. and 3. by studying the models’ likelihood in- and out-of-sample for parameters estimated over different train windows. We show that models with larger off-sample likelihoods lead to better performing portfolios only for shorter train sets. For larger train sets, we found that portfolio performances deteriorate and detaches from the models’ likelihood, highlighting the role of non-stationarity. Investigating the out-of-sample likelihood of individual observations we show that the system changes significantly through time. Larger estimation windows lead to stable likelihood in the long run, but at the cost of lower likelihood in the short term: the “optimal” fit in finance needs to be defined in terms of the holding period. Lastly, we show that sparse models outperform full-models and conventional GARCH extensions by delivering higher out of sample likelihood, lower realized volatility and improved stability, avoiding typical pitfalls of conventional portfolio optimization approaches.