"...one of the more recent financial inventions has left an indelible impact on the market and created a world of opportunity for retail investors at the same times. We're talking about the advent and the evolution of the exchange-traded fund (ETF).... Most industry followers estimate the number of ETFs available to U.S. investors will reach 1,000 sometime in 2010.
A Real Threat to Mutual Funds
One statement that investors have heard over and over again about ETFs is that they're mutual funds that trade like stocks with smaller management expense ratios. This may sound like an over-simplification, but the statement is essentially true."