ETFs are just what their name implies: baskets of securities that are traded, like individual stocks, on an exchange. Unlike regular open-end mutual funds, ETFs can be bought and sold throughout the trading day like any stock.
Most ETFs charge lower annual expenses than index mutual funds. However, as with stocks, one must pay a brokerage to buy and sell ETF units, which can be a significant drawback for those who trade frequently or invest regular sums of money.
They first came into existence in the USA in 1993. It took several years for them to attract public interest. But once they did, the volumes took off with a vengeance. Over the last few years more than $120 billion (as on June 2002) is invested in about 230 ETFs. About 60% of trading volumes on the American Stock Exchange are from ETFs. The most popular ETFs are QQQs (Cubes) based on the Nasdaq-100 Index, SPDRs (Spiders) based on the S&P 500 Index, iSHARES based on MSCI Indices and TRAHK (Tracks) based on the Hang Seng Index. The average daily trading volume in QQQ is around 89 million shares.
Their passive nature is a necessity: the funds rely on an arbitrage mechanism to keep the prices at which they trade roughly in line with the net asset values of their underlying portfolios. For the mechanism to work, potential arbitragers need to have full, timely knowledge of a fund's holdings.
