It was State Street Global Advisors who launched the first Exchange Traded Fund (ETF) in 1993 with the introduction of the SPDR. Since then, ETFs have continued to grow in popularity but also gather assets at a rapid pace. The easiest way to understand ETFs is to think of them as mutual funds that trade like stocks. Of course, trading like a stock is just one of the many features that make ETFs so popular. Let's go over these attractive features.

The Benefits of Trading Like a Stock
The easiest way to highlight the advantage of the ETF trading like a stock is to compare it to the trading of a mutual fund. Mutual funds are priced once per day, at the close of business. Everyone purchasing the fund that day gets the same price, regardless of the time of day their purchase was made.

Because, like traditional stocks and bonds, ETFs can be traded intraday, they provide an opportunity for investors to bet on the direction of shorter-term market movements through the trading of a single security. For example, if the S&P 500 is experiencing a steep rise in price through the day, investors can try to take advantage of this rise by purchasing an ETF that mirrors the index (such as a SPDR), hold it for a few hours while the price continues to rise and then sell it at a profit before the close of business. Investors in a mutual fund that mirrors the S&P 500 do not have this capability - by nature of the way it is traded, a mutual fund does not allow investors to take advantage of the daily fluctuations of its basket of securities.

Low Expense Ratios
Everybody loves to save money, particularly investors who take their savings and put them to work in their portfolios. ETFs offer all of the benefits associated with index funds - such as low turnover and broad diversification (not to mention the often-cited statistic that 80% of the more expensive actively managed mutual funds fail to beat their benchmarks) - plus ETFs have lower management fees.

Compare the Vanguard 500 Index Fund, often cited as one of the lowest of the low-cost index funds, and the SPDR 500 ETF. The Vanguard fund's expense ratio of 18 basis points is significantly lower than the 100+ basis points often charged by actively managed mutual funds. But when compared to the SPDR's 11-basis-point expense ratio, the Vanguard fund's expense ratio looks quite high. In fact the SPDR is 40% lower, which is tough to argue with.

Diversification
ETFs come in handy when investors want to create a diversified portfolio. There are hundreds of ETFs available, and they cover every major index (those issued by Dow Jones, S&P, Nasdaq) and sector of the equities market (large caps, small caps, growth, value). There are international ETFs, regional ETFs (Europe, Pacific Rim, emerging markets) and country-specific (Japan, Australia, U.K.) ETFs. Specialized ETFs cover specific industries (technology, biotech, energy) and market niches (REITs, gold).

And ETFs cover also other asset classes, such as fixed income. While ETFs offer fewer choices in the fixed-income arena, there are still plenty of options, including ETFs composed of long-term bonds, mid-term bonds and short-term bonds. While fixed-income ETFs are often selected for the income produced by their dividends, some equity ETFs also pay dividends. These payments can be deposited into a brokerage account or reinvested. If you invest in a dividend-paying ETF, be sure to check the fees prior to reinvesting the dividends, as some firms offer free dividend reinvestment, while others do not.

[Note: ETF selections in the ShareBuilder 401(k) are limited to the 15 ETFs presented in the Investment Center.]

Studies have shown that asset allocation is a primary factor responsible for investment returns, and ETFs are a convenient way for investors to build a portfolio that meets specific asset allocation needs. For example, an investor seeking an allocation of 80% stocks and 20% bonds can easily create that portfolio with ETFs. That investor can even further diversify by dividing the stock portion into large-cap growth and small-cap value stocks, and the bond portion into mid-term and short-term bonds. Or, it would be just as easy to create an 80/20 bond-to-stock portfolio that includes ETFs tracking long-term bonds and those tracking REITs. The large number of available ETFs enables investors to quickly and easily build a diversified portfolio that meets any asset allocation model.

Summary
The reasons for the popularity of ETFs are easy to understand. This simple, convenient and diversified package results in an investment that some people believe will one day replace traditional mutual funds in most investor's portfolios.