The job duties of an investment portfolio manager are to optimize the investments within a client's portfolio, within the guidelines set by the client. Depending on the client and what they specifically are asking for, the PM may be responsible for setting the weightings in various asset classes, eg what percent of the portfolio will be in stocks, what percent of the portfolio will be in bonds, etc. Alternatively, the PM may be asked just to focus on one asset class and then focus on making the best investments within that sector. For example, if a client hires a PM to manage stocks, the PM would try to buy the stocks they think will go up in price the most and sell the ones they think will drop in price. The PM's duty is to try to make the best investments according to the client's wishes.