It tracks the Russell 2500 Index. From the constituents of the Russell 3000, it holds roughly 2,500 of the smaller companies by market capitalization, weighted by float-adjusted market cap, which replicates the entire US small and mid cap segment. It does not pick individual stocks and simply follows the structure of the index.

It suits long-term diversified investors who want to add small and mid cap exposure in one step to a portfolio centered on large caps.

It is a passive (index tracking) ETF managed by BlackRock iShares.

It replicates the small and mid cap segment of the Russell 3000, excluding large caps, using representative sampling. Because the number of constituents is large, the fund holds a sample that resembles the characteristics of the index instead of every stock, and additions and removals are reflected when the index is reconstituted. Sector allocation also follows the index exactly.

• Combines mid caps and small caps in one product, so there is no gap in the size range
• Expense level that is low compared with the small and mid cap category average
• Float-adjusted weighting reflects the shares actually available for trading

Assets under management (AUM) are $4.2B, and the total expense ratio (Expense Ratio) is 0.15% per year.

Compared with broad-market core ETFs, the fee is somewhat higher, but there is the convenience of not having to buy separate small and mid cap exposure.

Small and mid cap stocks react more sensitively than large caps to interest rates and economic expectations. They have repeatedly shown relative strength when rate pressure eases, and fallen harder when credit conditions deteriorate. Given the nature of the index, the macro direction drives performance more than individual stock issues do.

As the weight of large caps in a US equity allocation grows, demand for small and mid cap complements emerges. Capital tends to flow into this segment when expectations build that the economy is passing its trough, and returns to large cap core holdings during risk-off periods. Liquidity is thinner than in large cap core products.

Its strength is diversification that fills the small and mid cap range in one step, while its weaknesses are higher volatility and a heavier fee burden compared with large cap core funds.

Funds in the comparison table such as ITOT and SCHB are broad core holdings that cover the entire US market, with lower fees and larger assets. Because they include large caps, their character is different. VXF covers the segment excluding the S&P 500 and is a close alternative to this product, while IWV covers the entire Russell 3000 and OEF sits on the opposite side, focused on mega caps. For a narrower focus on small and mid caps alone, you can consider IWM, IJH and IJR, and VTWO is among the low-fee substitutes.

Here is what to check before buying. Deciding first what role small and mid cap exposure will play in your portfolio makes it easier to set the weighting. Also check for overlapping holdings with the core products you already own.

During an economic slowdown, small and mid cap stocks sell off earlier and more deeply than large caps. Because the fund holds the whole index, unprofitable companies come along with it, and worsening credit conditions can weigh on the lower end of the index and delay a recovery.

It works well as a complement to a large cap centered portfolio. If cost is the priority, choose a broad core fund; if you want to separate out small and mid cap exposure clearly, choose this product. We recommend setting the weighting according to the volatility you can tolerate.