An investment bank is a financial institution that assists individuals, corporations and governments in raising capital by underwriting and/or acting as the client's agent in the issuance of securities. An investment bank may also assist companies involved in mergers and acquisitions, and provide ancillary services such as market making, trading of derivatives, fixed income instruments, foreign exchange, commodities, and equity securities.
Unlike commercial banks and retail banks, investment banks do not take deposits. From 1933 (Glass–Steagall Act) until 1999 (Gramm–Leach–Bliley Act), the United States maintained a separation between investment banking and commercial banks. Other industrialized countries, including G8 countries, have historically not maintained such a separation.