The kind of bank which will be formed in any community is largely determined by the needs of that community. Under the general types just discussed we find the following classifications: National, State and private banks, and the banking departments of some trust companies which perform the functions of a commercial bank. In addition, a private bank usually does either an investment or a savings business. Savings banks are either mutual or stock or perhaps but a department of a commercial bank. Many banks perform trust functions, although originally this work was monopolized among banks by trust companies incorporated for that express purpose; today we find National and State banks also acting in fiduciary capacities. Many houses call themselves investment bankers, principally dealers in bonds, mortgages, and acceptances and the bond departments of banks and trust companies.