The selection of investments must adhere to the style of the portfolio. For instance, a large-capitalization growth manager might be screening for only companies that have a market-capitalization in excess of $3 billion and earnings growth characteristics that exceed its industry. Therefore, the portfolio manager would not even consider a $500 million utility stock with a 6 percent dividend yield.

Once investment opportunities are recognized, portfolio managers must decide what percentage of their portfolio to allocate to the respective security. This decision is based on the mandate of the portfolio --active or passive --and the risk expectation of the overall portfolio. For example, riskier portfolios invest in a small number of securities and take large "bets." The popular Janus Twenty fund invests in only 20 liquid large-capitalization companies. Alternatively, diversified portfolios may invest in over 100 securities to spread the risk of any one holding.

Portfolio managers also spend time meeting with their clients to review investment strategy and performance results. While marketing and sales professionals lead this process, portfolio managers are often an integral part of client discussions. In the mutual fund world, portfolio managers don't spend time talking to individual customers, but they are often called on to present at sales conferences and at product road shows. However, institutional and high-net-worth portfolio managers have fewer clients, and they only meet with them one to two times a year.

Portfolio managers are the most seasoned investment professionals in the firm. Typically, people with at least 7 to 10 years of investment experience occupy these positions, and most have either an MBA or a CFA designation.