Aggregation risk is the possibility that one incident causes losses across multiple connected customers, organizations, or systems. It arises when many parties depend on the same cloud provider, software component, network, or other critical service, so a shared weakness or outage can affect them at once.
In cyber security and insurance, this matters because a single event can create correlated claims and widespread disruption rather than isolated losses. Attackers may exploit a common supplier or vulnerable component to reach many victims; defenders and insurers assess this exposure by mapping dependencies, checking supplier controls, and planning alternatives for critical services. Better visibility helps estimate the potential blast radius and prepare for recovery.