This paper proposes a conceptual framework for understanding geoeconomic fragmentation risk as a multidimensional condition and operationalizes it through a composite index for the European Union (EU-27), linking macro-level fragmentation to firm-level strategic behavior under uncertainty. We argue that fragmentation is not captured by traditional indicators of macroeconomic risk, political instability, or trade openness. Rather, it is a multidimensional condition in which cross-border economic relations become strategically contested, politically coercible, and institutionally uncertain. To formalize this argument, we synthesize Knight's distinction between measurable risk and genuine uncertainty, Luttwak's conception of geo-economics as strategic conflict, and Turner's systemic account of interdependence, engaging with contemporary IPE scholarship on weaponized interdependence, sanctions effectiveness, trade discrimination and industrial policy, and geoeconomic statecraft. On that basis, we propose a composite index built from four dimensions: structural vulnerability, policy uncertainty, coercive restrictions, and realized fragmentation. The measure draws on country-risk data, uncertainty indexes, sanctions databases, and bilateral trade and investment data. The result is a framework that sharpens the concept of geoeconomic fragmentation risk and offers an operational path for empirical testing in corporate finance, international business, and political economy.