The financial system is a set of institutions, such as banks, insurance companies, and stock exchanges, that permit the exchange of funds. Financial systems exist on firm, regional, and global levels. Borrowers, lenders, and investors exchange current funds to finance projects, either for consumption or productive investments, and to pursue a return on their financial assets. The financial system also includes sets of rules and practices that borrowers and lenders use to decide which projects get financed, who finances projects, and terms of financial deals. Financial markets involve borrowers, lenders, and investors negotiating loans and other transactions. In these markets, the economic good traded on both sides is usually some form of money: current money (cash), claims on future money (credit), or claims on the future income potential or value of real assets (equity). These also include derivative instruments. Derivative instruments, such as commodity futures or stock options, are financial instruments that are dependent on an underlying real or financial asset's performance. In financial markets, these are all traded among borrowers, lenders, and investors.