The determinants of stock-bond return correlations

I study the options-implied market risks that affect US stock-bond correlations from 2007 to 2021. I discover that US stock and bond market uncertainty, stock market tail risk, and global credit-default risk are dominant contributors to changing stock-bond correlations during the global financial crisis (GFC) period. However, these market risks collectively contribute much less to time-varying correlations in the post-GFC period. Furthermore, stock-bond correlations rise in times of rising US and global bond market risks. Rising stock market uncertainty raises stock-bond correlations in the GFC period but lowers them in the post-GFC period. My results disentangle the risks of stock and bond markets and show that equity tail risk, bond market risk, and stock market uncertainty are dominant factors in changing stock-bond diversification benefits in periods of market turmoil.