NAV is calculated by adding the value of all of the investments in the fund and dividing by the number of shares of the fund that are outstanding. NAV calculations are required for all mutual funds (or open-end funds) and closed-end funds. The price per share of a closed-end fund will trade at either a premium or a discount to the NAV of that fund, based on market demand. Closed-end funds generally trade at a discount to NAV.