1) is a concentration of insurance risks in one company to the extent that may lead to multiple losses due to a single insurance event; 2) is a concentration of insured facilities on the same territory, street, house, port, railway station, ship, which in case of a simultaneous insurance event (for example, an earthquake) may lead to violation of insurer’s financial stability. Cumulation can be taken into account when determining a portion of risk remaining on insurer’s retention.