<p>This study attempts to inspection the efficient of using cash holdings whether is improved after setting up audit committee sound corporate governance from the perspective of reducing agency costs. We use the difference in difference method to investigate the effect of oversight of audit committee from 2007 to 2010 the company with audit committee for sample. The empirical results show that the using efficiency of cash holdings isn’t promoted after setting up audit committee with all listed companies sample. We further divided the sample into the over-the-counter (OTC) market and the Taiwan Stock Exchange (TSE) market according to the stock market feather. The empirical indicated that the Taiwan Stock Exchange (TSE) market listed sample exhibited the effect of oversight of audit committee; however, the over-the-counter (OTC) market listed is not. It indicated that the different market structure did affect the effect of oversight of audit committee.</p>

This study aimed to uncover the impact of COVID-19 on the leading cryptocurrency (Bitcoin) and on sustainable finance with specific attention to their potential long memory properties. In this article, the application of the selected methodologies is based on a fractal and entropy analysis of the econometric model in the financial market. To detect the regularity/irregularity property of a time series, approximate entropy is introduced to measure deterministic chaos. Using daily data for Bitcoin and sustainable finance, namely DJSW, Green Bond, Carbon, and Clean Energy, we examine long memory behaviour by employing a rescaled range statistic (R/S) methodology. The results of the research present that the returns of Bitcoin, the Dow Jones Sustainability World Index (DJSW), Green Bond, Carbon, and Clean Energy have a significant long memory. Contrastingly, an interdisciplinary approach, namely wavelet analysis, is also used to obtain complementary results. Wavelet analysis can provide warning information about turmoil phenomena and offer insights into co-movements in the time–frequency space. Our findings reveal that approximate entropy shows crisis (turmoil) conditions in the Bitcoin market, despite the nature of the pandemic’s origin. Crucially, compared to Bitcoin assets, sustainable financial assets may play a better safe haven role during a pandemic turmoil period. The policy implications of this study could improve trading strategies for the sake of portfolio managers and investors during crisis and non-crisis periods.