We examine how economic policy uncertainty (EPU) influences realized variance dependency and tail-risk synchronization across major cryptocurrencies. Using 5-min high-frequency returns to construct realized variance and signed jump variance measures, we document that global and Western EPU (the US, UK, France) significantly strengthen both variance dependency (VD) and signed jump variance dependency (SJVD) among the top 15 cryptocurrencies, whereas Asian EPUs exhibit weaker and less consistent effects. The sensitivity of SJVD is particularly pronounced, reflecting the asymmetric transmission of tail risk during uncertainty shocks. These findings remain robust after controlling for Bitcoin’s realized volatility and hold in post-COVID subsample analysis. Our results suggest that cryptocurrency markets exhibit greater systemic interconnectedness and heightened tail-risk co-movements during periods of elevated policy uncertainty, with important implications for risk management and financial stability monitoring.
