IJR delivers one of the strongest offerings in the US small-cap segment. The fund tracks the S&P SmallCap 600 Index. As a part of BlackRocks Core ETFs, the fund is often used as a portfolio building block. IJR holds just a fraction of the names in our neutral benchmark index, giving the fund an appearance of being under-diversified. However, the fund still reflects the market quite accurately in both performance and coverage. IJR's avoidance of the most illiquid small-cap names may help explain its strong liquidity: its compact basket is easier for market makers to hedge. Investors should consider all in costs when comparing similar products, the fund is tough to beat for efficient, core small-cap exposure.