An exchange-traded fund (ETF) is a fund that pools investors’ money in a variety of investments.  Unlike traditional mutual funds, most investors buy and sell shares of ETFs from other investors on an exchange rather than directly from the issuer.  In addition, ETFs cannot market themselves to consumers as “mutual funds” because they are not necessarily subject to all the requirements applicable to traditional mutual funds.  Nevertheless, ETFs are usually registered with the U.S. Securities and Exchange Commission under the same statutory authorities as traditional mutual funds and unit investment trusts.