Concentration risk arises when too much of an organization's operations depends on one provider, platform, technology or location. A failure at that shared point can affect many services at the same time, even if each service appears separate to its users.
A company may host most applications on one cloud, use one identity provider for employee access and depend on one security update mechanism across thousands of computers. A serious outage or faulty change can therefore spread across business functions.
Using several vendors does not automatically remove the risk. They may share an underlying cloud, network, software library or subcontractor. Diversification can also add integration costs and new operational complexity, so resilience requires understanding actual dependencies.
Map critical suppliers and shared components, test recovery procedures and identify where alternative capacity is practical. Prioritize backups, independent access paths and clear incident ownership for the dependencies whose failure would hurt the business most.