This paper develops and applies a portfolio-based framework for assessing systemic risk in cross-border banking networks. Relying on three complementary measures, it captures distinct risk dimensions related to diversification, institution-specific shocks, and contagion potential. Despite limitations stemming from indirect exposures and the lack of bank-level bilateral data, the approach remains informative for surveillance, enabling the identification of jurisdictions that warrant closer supervisory attention. The empirical application shows that systemic risk profiles vary significantly across banking systems, with diversification offering resilience in some cases and concentrated exposures amplifying vulnerabilities in others. The results underscore the importance of adopting multi-pronged analytical methods in supervisory practice to better target scarce monitoring resources toward emerging systemic vulnerabilities.