How Regulation and Global Standing Shape Stock Market Co‐Movements: A <scp>G20</scp> Panel Study

ABSTRACT Motivated by post‐2020 fragmentation and underexplored institutional‐geopolitical drivers, we examine how regulatory quality (RQ) and global power (GP) shape stock‐market co‐movements across 17 G20 economies. We estimate time‐varying correlations via ADCC‐GARCH, construct a scaled correlation index, and apply panel ARDL. We find that higher RQ and stronger GP raise long‐run integration; effects appear conditional rather than purely additive. Results are robust to alternative openness proxies (trade vs. GDP). Our contributions are a unified RQ‐GP framework, a correlation index for integration monitoring, and policy‐relevant evidence on how institutional quality and geopolitical standing condition diversification and financial stability.