Exchange Traded Funds (ETFs) — a group of related equity products that represent different indices, market sectors and groups, and which trade like stocks — have been enormously successful since the first few were launched in the 1990s. The two most popular are the Nasdaq 100 index–tracking stock (QQQ) and S&P 500 index–tracking stock (SPY).

However, there are many more available – more than 120 are listed at the Nasdaq Web site for evaluation (see "Funds for all", Active Trader, November 2002, p. 28), ranging from sector indices (biotechnology, IBB) to country–specific instruments (the Australian stock market, AAA) to Treasury bond index funds (TLT).