This ETF is one of several offering exposure to the Russell 2000 Index, a widely followed measure of small cap U.S. stocks. Given this investment objective, IWM may be useful in a number of different ways; more active investors may use this fund as a way to establish short-term exposure to a risky asset class when risk tolerance is expected to climb, while IWM can also be appealing as a way of accessing an asset class that should be included in any long-term, buy-and-hold portfolio.
IWM has appeal as a portfolio "building block" thanks to the balanced nature of the underlying portfolio and the relative cost efficiency offered. Every sector of the U.S. economy is well represented in the underlying portfolio, and no one stock accounts for a significant portion of assets. Moreover, IWM is relatively cheap, and the ability to trade commission free on Fidelity platforms may enhance the value proposition. However, it should be noted that Vanguard's VTWO is linked to the exact same index (the Russell 2000), but charges a significantly lower expense ratio. For investors concerned about minimizing costs, that Vanguard fund may be a better choice.