10.1. The balance sheets and accumulation accounts form a group of accounts that are concerned with the values of the assets owned by institutional units or sectors, and their liabilities, at particular points in time and with the evolution of those values over time. Balance sheets measure the values of stocks of assets or liabilities and are typically compiled at the beginning and end of the accounting period. The total value of the assets owned by an institutional unit or sector minus the total value of its liabilities is described as its net worth. It is a measure of the wealth of a unit or sector at a point in time. The accumulation accounts record the changes in the values of the assets, liabilities and net worth that take place during the accounting period. They are flow accounts, whose entries depend on the amounts of economic or other activities that take place within a given period of time and on transactions and other flows associated with them.