| ICI | See Investment Company Institute | |
| ICSD | See International Councils of Securities Dealers | |
| individual investor | A person who buys or sells securities for his or her own account. The individual investor is also called a retail investor or retail shareholder. | |
| INSTINET | See The Institutional Networks Corporation | |
| IOSCO | See International Organization of Securities Commissions | |
| initial public offering (IPO) | A company's first sale of stock to the public. Companies making an IPO are seeking outside equity capital and a public market for their stock. (See syndicate, underwriter) | |
| Industry Support Information Services (ISIS) | The ISIS system supports all NASD regulatory activities set forth in its charter and the Securities Exchange Act of 1934. The system includes information applications for securities industry personnel and issuer companies, including databases on registered personnel, issues, members, and market data users. | |
| inside market | The highest bid and the lowest ask (offer) prices among all Market Makers competing in a Nasdaq security; the best bid and ask prices for a security. (See best bid, best ask) | |
| inside quote | See inside spread | |
| inside spread (inside quote) | The difference between the best bid and best ask among all securities is the highest bid and lowest offer being quoted among all of the Market Makers competing in a security. Since the spread is the aggregate of individual Market Maker spreads, it is narrower than an individual dealer spread or quote. (See Market Maker, Market Maker spread) | |
| institutional investor | A bank, mutual fund, pension fund, or other corporate entity that trades securities in large volumes. (See also buy-side trader, fourth market, qualified institutional investor) | |
| Institutional Networks Corporation (INSTINET) | A computerized service that allows subscribers to display tentative bid and ask quotes. INSTINET registered as a stock exchange with the Securities and Exchange Commission; it supports the "fourth market." (See fourth market, SelectNet) | |
| Intermarket Surveillance Group (ISG) | A group that coordinates surveillance and investigations among NASD and other U.S. and foreign exchanges trading in securities, options, and futures and foreign securities. (See market surveillance) | |
| Intermarket Trading System (ITS) | A computer system that interconnects competing exchange markets for the purpose of choosing the best market. ITS is operated by Securities Industry Automation Corporation (SAC). (See Computer Assisted Execution System) | |
| International Councils of Securities Dealers (ICSD) | An international organization of self-regulatory and securities-industry organizations. ICSD seeks to foster mutual understanding among members, and to promote stable and efficient securities markets. | |
| International Organization of Securities Commissions (IOSCO) | IOSCO attempts to harmonize international securities regulation, and supports the development of securities markets around the world. | |
| international linkages | Intermarket connections of world securities markets. | |
| Investment Company Institute (ICI) | The U.S. trade association for the mutual fund industry. Investment companies create and maintain mutual funds and investment trusts. | |
| investment banking, securities business | The business carried on by a broker or dealer; a business that deals in government or municipal securities; a business that underwrites or distributes securities issues; a business that buys or sells securities for itself or on the account of others. The definition does not include banks or bank departments. (See underwriter) | |
| investor | A person who buys or sells securities for his or her own account or the account of others. (See individual investor, institutional investor) | |
| IPO | See initial public offering | |
| ISG | See Intermarket Surveillance Group | |
| ISIS | See Industry Support Information Services | |
| issuer | A corporation that has distributed to the public securities registered with the Securities and Exchange Commission. | |
| ITS | See Intermarket Trading System | |
| ITS/CAES | See Intermarket Trading System/Computer Assisted Execution System |
