Closed-end funds are baskets of stocks that are grouped according to an investment objective and overseen by a manager. But unlike open-end funds, which continue to increase their asset base by selling to new shareholders, closed-end funds bring in assets by selling a fixed number of shares through an initial offering. After the initial sale, the closed-end fund's shares trade like stocks on exchanges like the NYSE or the AMEX. Low demand for a fund can cause closed-end shares to trade at discounts to net asset value. High demand can create premiums to NAV.