Purpose: The focus of the current research is to examine whether mixed-frequency investor sentiment affects stock volatility in the China A-shares stock market.Design/methodology/approach: Mixed-frequency sampling models are employed to find the relationship between stock market volatility and mixed-frequency investor sentiment. Principal analysis and MIDAS-GARCH model are used to calibrate the impact of investor sentiment on the large-horizon components of volatility of Shanghai composite stocks.Findings: The results show that the volatility in Chinese stock market is positively influenced by B–W investor sentiment index, when the sentiment index encompasses weighted mixed frequencies with different horizons. In particular, the impact of mixed-frequency investor sentiment is most significantly on the large-horizon components of volatility. Moreover, it is demonstrated that mixed-frequency sampling model has better explanatory powers than exogenous regression models when accounting for the relationship between investor sentiment and stock volatility.Practical implications: Given the various unique features of Chinese stock market and its importance as the major representative of world emerging markets, the findings of the current paper are of particularly scholarly and practical significance by shedding lights to the applicableness GARCH-MIDAS in the focused frontiers.Originality/value: A more accurate and insightful understanding of volatility has always been one of the core scholarly pursuits since the influential structural time series modeling of Engle (1982) and the seminal work of Engle and Rangel (2008) attempting to accommodate macroeconomic factors into volatility models. However, the studies in this regard are so far relatively scarce with mixed conclusions. The current study fills such gaps with improved MIDAS-GARCH approach and new evidence from Shanghai A-share market.

Mixture copulas are popular and essential tools for studying complex dependencies among variables. However, selecting the correct mixture models often involves repeated testing and estimations using criteria such as AIC, which could require effort and time. In this paper, we propose a method that would enable us to select and estimate the correct mixture copulas simultaneously. This is accomplished by first overfitting the model and then conducting the Bayesian estimations. We verify the correctness of our approach by numerical simulations. Finally, the real data analysis is performed by studying the dependencies among three major financial markets.

The Winter Olympic Games stimulate significant infrastructure development, yet post-Games venue utilization remains a pressing challenge. Traditional survey-based assessments are often resource-intensive and lack the capacity for continuous, large-scale monitoring. This study employs nighttime light (NTL) remote sensing data to analyze 209 Winter Olympic Game venues, utilizing time series analysis, change point detection, and seasonal decomposition. Results indicate that 32.06% of venues exhibit a significant increase in activity, while 12.92% experience a decline significantly. Two distinct utilization patterns emerge: outdoor sports venues for pre-2000 Games are more likely to face post-Games underutilization due to geographic isolation and high maintenance costs, whereas urban indoor venues can sustain long-term use through multi-purpose adaptability and accessibility. The findings confirm NTL data as an effective real-time monitoring tool, supporting data-driven legacy planning. This study highlights the significance of multi-purpose design, tourism integration, and policy-driven repurpose in ensuring the long-term sustainability of Olympic infrastructure investments.