The iShares Russell 2000 Growth ETF (IWO) is a popular exchange-traded fund that tracks the performance of growth stocks within the Russell 2000 index. The Russell 2000 index represents small-cap companies in the US market, and IWO specifically focuses on those companies that exhibit growth characteristics, such as high price-to-book ratios, high earnings growth, and strong sales momentum. Yahoo Finance is a widely used platform for investors to monitor the performance of IWO and access related information.