Third-party concentration risk is the danger that builds up when many organizations rely on the same cloud, AI, software, or managed-service provider. If that provider fails, is attacked, or changes service terms, the impact can spread quickly across a whole sector instead of staying isolated to one company.
In cyber security, this matters because concentration creates a single point of failure and a high-value target. Attackers may focus on one supplier to reach many downstream victims, or a software flaw in a shared platform can expose multiple institutions at once. Defenders manage this risk by mapping critical dependencies, reviewing vendor security, testing fallback plans, and avoiding blind reliance on one provider for essential services. In regulated industries such as finance, concentration risk is also a resilience issue: organizations need to prove they can keep operating if a shared technology layer is disrupted.