An entity whose income exceeds their expenditure can lend or invest the excess income. On the other hand, an entity whose income is less than its expenditure can raise capital by borrowing or selling equity claims, decreasing its expenses, or increasing its income. The lender can find a borrower, a financial intermediary such as a bank, or buy notes or bonds in the bond market. The lender receives interest, the borrower pays a higher interest than the lender receives, and the financial intermediary pockets the difference.
A bank aggregates the activities of many borrowers and lenders. A bank accepts deposits from lenders, on which it pays interest. The bank then lends these deposits to borrowers. Banks allow borrowers and lenders, of different sizes, to coordinate their activity. Banks are thus compensators of money flows in space.
A specific example of corporate finance is the sale of stock by a company to institutional investors like investment banks, who may sell it on to private investors, or other financial institutions such as pension funds. The stock give part ownership in that company in proportion to shares owned.
