Investment Bank is a financial intermediary that performs a variety of services. This includes underwriting, acting as an intermediary between an issuer of securities and the investing public, facilitating mergers and other corporate reorganizations, and also acting as a broker for institutional clients.
Unlike commercial banks and retail banks, investment banks do not take deposits. There are two main lines of business in investment banking. Trading securities for cash or for other securities (i.e., facilitating transactions, market-making), or the promotion of securities (i.e., underwriting, research, etc.) is the "sell side", while dealing with pension funds, mutual funds, hedge funds, and the investing public (who consume the products and services of the sell-side in order to maximize their return on investment) constitutes the "buy side". Many firms have buy and sell side components.
The role of the investment bank begins with pre-underwriting counseling and continues after the distribution of securities in the form of advice.
Investment Banker is a person representing a financial institution that is in the business of raising capital for corporations and municipalities.