Financial contagion

Financial contagion is the spread of market distress from one institution, asset class, or geographic region to others through mechanisms that are not explained by fundamental economic linkages. The contagion propagates through network interdependencies — overlapping portfolios, common lender relationships, and correlated risk exposures — that amplify localized shocks into systemic crises. Unlike standard epidemic models, financial contagion is often discontinuous: a network can appear stable until a single node crosses a critical leverage threshold, triggering a cascade of forced liquidations that rewires the network in real time. The 2008 global financial crisis is the canonical case, but the same dynamics appear in cryptocurrency collapses, sovereign debt crises, and banking panics. What regulators consistently fail to model is the adaptive threshold behavior of market participants: after a crash, traders raise their risk thresholds, making the system paradoxically more fragile to the next shock because the same network topology now supports less absorptive capacity.