Global crises have created unprecedented challenges for communities and economies across the world, triggering turmoil in global finance and economy. This study adopts the dynamic conditional correlation multiple generalized autoregressive conditional heteroskedasticity (DCC–MGARCH) model to explore contagion effects across financial markets in crisis. The main findings are as follows: (1) the financial crisis and COVID-19 pandemic intensified the connection between the Chinese and US stock markets in the short term; (2) the dynamic conditional correlations (DCCs) during the COVID-19 pandemic are higher than those during the 2008 financial crisis owing to the further opening of the Chinese capital market, and financial institutions’ investments in the European market are higher than those in the American markets; (3) a stepwise increase is observed in the dynamic conditional correlation between the returns on the S&P 500 Index and SSEC during and after the onset of a destructive crisis; and (4) a unidirectional contagion effect exists between the Chinese market and US market, and the Hong Kong stock market contributes to the risk spillover. Effective transmission channels of external negative shocks may be investors’ sentiments, financial institutions, and the RMB exchange rate in the stock markets. This study provides useful suggestions to authorities formulating financial regulations and investors diversifying risk investments.

This study aims to explore the sustainable development of the regional economy from the perspective of human capital. Based on the panel data from 2005 to 2019 in Shandong Province, China, this study first analyzes the interactive coupling mechanism between human capital and sustainable economic growth, and then constructs the evaluation model of coupling coordination degree. Results reveal that Shandong Province’s human capital and sustainable economic growth gradually increased; the coupling coordination degree of human capital and sustainable economic growth changed from a state of mild imbalance to slight coordination; sustainable economic growth lagged human capital development; education scale, innovation capacity, growth level, economic openness, and investment and consumption level are the key factors affecting sustainable economic development. Through the above research, the study puts forward policy suggestions conducive to sustainable development in China.