An exchange-traded fund (or ETF) is an investment vehicle traded on stock exchanges, much like stocks. An ETF holds assets such as stocks or bonds and trades at approximately the same price as the net asset value of its underlying assets over the course of the trading day. Most ETFs track an index, such as the S&P 500 or MSCI EAFE. ETFs may be attractive as investments because of their low costs, tax efficiency, and stock-like features. In a survey of investment professionals conducted in March 2008, 67% called ETFs the most innovative investment vehicle of the last two decades and 60% reported that ETFs have fundamentally changed the way they construct investment portfolios.The Impact of Exchange Traded Products on the Financial Advisory Industry: A Joint Study of State Street Global Advisors and Knowledge@Wharton (2008).

Only so-called authorized participants (typically, large institutional investors) actually obtain or redeem shares of an ETF directly from the fund manager, and then only in creation units, large blocks of tens of thousands of ETF shares that can be exchanged in-kind with baskets of the underlying securities. Authorized participants may hold the ETF shares or they may act as market makers on the open market, using their ability to exchange creation units with their underlying securities to provide liquidity of the ETF shares and help ensure that their intraday market price approximates the net asset value of the underlying assets. Other investors, such as individuals using a retail brokerage, trade ETF shares on this secondary market.

An ETF combines the valuation feature of a mutual fund or unit investment trust, which can be purchased or redeemed at the end of each trading day for its net asset value, with the tradability feature of a closed-end fund, which trades throughout the trading day at prices that may be more or less than its net asset value. Closed-end funds are not considered to be exchange-traded funds, even though they are funds and are traded on an exchange. ETFs have been available in the US since 1993 and in Europe since 1999. ETFs traditionally have been index funds, but in 2008 the U.S. Securities and Exchange Commission began to authorize the creation of actively-managed ETFs. Exchange-Traded Funds, SEC Release Nos. 33-8901, IC-28193, 73 Fed. Reg. 14618 (Mar. 11, 2008).

Structure

ETFs offer public investors an undivided interest in a pool of securities and other assets and thus are similar in many ways to traditional mutual funds, except that shares in an ETF can be bought and sold throughout the day like stocks on a securities exchange through a broker-dealer. Unlike traditional mutual funds, ETFs do not sell or redeem their individual shares at net asset value, or NAV. Instead, financial institutions purchase and redeem ETF shares directly from the ETF, but only in large blocks, varying in size by ETF from 25,000 to 200,000 shares, called "creation units." Purchases and redemptions of the creation units generally are in kind, with the institutional investor contributing or receiving a basket of securities of the same type and proportion held by the ETF, although some ETFs may require or permit a purchasing or redeeming shareholder to substitute cash for some or all of the securities in the basket of assets.