An "open end mutual fund" or "open end fund" is the most common type of mutual fund. Investors may purchase units of the fund directly from the fund sponsor, and can redeem the units through the fund sponsor. Being open ended means that, at the end of every day, the fund issues new shares to investors and buys back shares from investors wishing to cash out of the fund. The price for buying or selling the fund's units is pegged to the net asset value, or NAV, of the fund. The net asset value is the current market value of a fund's holdings, usually expressed as a per-share amount.