In 1848, California's first financial institution—the Miners' Bank—was founded in San Francisco. Especially since 1904, when A. P. Giannini founded the Bank of Italy, now known as the Bank of America, California banks have pioneered in branch banking for families and small businesses. Today, California is among the leading states in branch banking, savings and loan associations, and credit union operations.
In 2002, there were 328 insured banks in California. As of September 2002, insured banks in California had total assets of $839 billion. Although net interest margins (NIMs) (the difference between the lower rates offered to savers and the higher rates charged on loans) for California's insured institutions declined in 2001/02, the state's median return on average assets (ROA) ratio (the measure of earnings in relation to all resources) increased, due in part to improved overhead efficiencies and gains in securities.
Until 30 June 1997, the State Banking Department administered laws and regulations governing state-chartered banks, foreign banks, trust companies, issuers of payment instruments, issuers of travelers' checks, and transmitters of money abroad. On 1 July 1997 a new department began supervising all of California's depository institutions. The Department of Financial Institutions now supervises over 700 commercial banks, credit unions, industrial loan companies, savings and loans, and other licensees formerly supervised by the State Banking Department.