A person or organization that makes investments in portfolios of securities on behalf of clients, in accordance with the investment objectives and parameters defined by these clients. An investment manager may be responsible for all activities associated with the management of client portfolios, from buying and selling securities on a day-to-day basis to portfolio monitoring, settlement of transactions, performance measurement, and regulatory and client reporting. Taobiz explains Investment Manager Investment managers can range in size from one- or two-person offices to large multi-disciplinary firms with offices in several countries. Fees charged by investment managers to their clients are generally based on a percentage of client assets under management (AUM). For example, an individual with a $5 million portfolio that is being handled by an investment manager who charges 1.5% annually would pay $75,000 in fees.