It tracks the STOXX U.S. Small Cap Factor Index. It is a rules-based product that adjusts weights among U.S. small-cap stocks by combining four style scores: value, quality, momentum and low volatility.

It suits long-term investors who want to diversify across U.S. small caps but prefer to refine stock weights with factor rules instead of simple market-cap weighting.

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

Within the U.S. small-cap universe, the index produces a composite score by combining value (measured by price relative to book value, plus dividend and earnings yield), quality (measured by financial soundness), momentum (measured by price and earnings trends) and low volatility (measured by historical return volatility). The index is built by increasing the weights of high-scoring stocks and reducing those of low-scoring ones.

• Combines four factors in one product, designed to avoid leaning toward any single style
• Relatively low cost within the small-cap category
• A broad set of holdings dilutes single-company risk

Assets under management (AUM) stand at $4.3B, and the expense ratio is 0.15% per year.

Small caps tend to have wider bid-ask spreads than large caps, so limit orders are generally preferable to market orders when trading.

Small caps are sensitive to interest rates and economic expectations, and have historically swung more widely than large caps. Because the factor rules look at low volatility and quality together, there are periods when performance diverges from that of a pure market-cap-weighted small-cap index.

U.S. equity flows tend to concentrate in large-cap core products, and inflows into small-cap factor products usually revive when expectations of an economic recovery build or when the interest rate direction shifts. When style preferences change, the direction of flows changes with them.

Its strengths are the combination of a low expense ratio, broad diversification and factor rules. Its weaknesses are the volatility inherent in small caps and periods when factors underperform.

Comparison tables include small-cap products that select stocks based on financial metrics, alongside large-cap and mid-cap products. Products in different size ranges are best referenced only in terms of expenses and fund size. If you want simple market-cap-weighted small-cap exposure, products such as IJR, VB and IWM are alternatives, and if you want to lean further toward small-cap value, AVUV and others are also worth considering.

Here are the items to check before buying this ETF. First, consider whether the nature of small caps as an asset class and the four factor rules fit your investment style and holding period.

When the drawdown of the small-cap index itself coincides with factor underperformance, the losses investors feel grow larger. When signs of an economic slowdown intensify, it is safer to plan position-size adjustments in advance.

It is a reasonable choice for investors who want rules-based exposure to U.S. small caps. If you prioritize cost and diversification, consider this ETF, and if you want simple index tracking, compare it with products such as IJR.