Individual companies in the Aegon Group are each subject to solvency supervision in their respective home countries. Based on  European Union legislation (EU Directive 98/79/EC, the Insurance Group Directive) adopted in 1998, EU supervisors, such as De  Nederlandsche Bank (DNB or Dutch Central Bank) are required to carry out “supplementary supervision” on EU insurance companies in  an insurance group. The supplementary supervision of insurance companies in an insurance group enables EU supervisors to make a  detailed assessment of the financial position of the EU insurance companies that are part of that group. The Directive requires DNB to  take into account the relevant financial affiliations between the insurance companies and other entities in the group. In this respect,  Aegon is required to submit reports to its supervisors twice a year setting out supplemental capital adequacy calculations of the  insurance companies, risk concentrations and significant transactions and positions between insurance and non-insurance companies in  the Aegon Group. Since the beginning of October 2009, Aegon has been subject to supplemental group supervision by the Dutch Central Bank in  accordance with the requirements of the European Union’s Financial Conglomerate Directive. Supplemental group supervision pursuant  to the Financial Conglomerate Directive includes supplementary capital adequacy requirements for financial conglomerates and  supplementary supervision on risk concentrations and intra-group transactions in the financial conglomerate.  Both the insurance and banking companies in the Aegon Group are required to maintain a minimum solvency margin based on local  requirements. The required solvency margin is the sum of the margins of each of Aegon’s insurance and banking subsidiaries, based on  the local requirements. Available liability capital includes shareholders’ equity, convertible core capital securities, perpetual capital  securities, and dated subordinated debt and senior debt.  Aegon faces a number of risks, some of which may arise from internal factors, such as inadequate compliance systems. Others, such as  movements in interest rates or unexpected changes in longevity or mortality trends, are external in nature. Aegon’s most significant risk  is to changes in financial markets, related particularly to movements in interest rates, equity and credit markets. These risks, whether  internal or external, may affect the company´s operations, its earnings, its share price, the value of its investments, or the sale of  certain products and services. The next two sections describe risks relating to Aegon’s businesses and risks relating to Aegon's common  shares. The following covers some key risk factors that may affect Aegon’s businesses and operations, as well as other risk factors that are  particularly relevant to Aegon in the ongoing period of significant economic uncertainty. Additional risks to which Aegon is subject to  include, but are not limited to, the factors mentioned under ‘Forward-looking statements’ (refer to page 354 and 355), and the risks of  Aegon’s businesses described elsewhere in this Annual Report. Factors additional to those discussed below or elsewhere in this Annual Report may also affect Aegon’s businesses and operations  adversely. The following risk factors should not be considered a complete list of potential risks that may affect Aegon and its  subsidiaries. Annual Report 2013 Supervision  Risk factors I - Risks relating to Aegon’s businesses Additional information 318