How to invest in size-factor ETFs

How do I invest in the size factor?

Statistical observations show that small companies (small caps) have tended to outperform large ones (large caps) in certain economic periods in the past. This research-based observation is referred to as the size factor. The only measure for the size that is used in this context is a firm's market capitalisation, i.e. the product of tradable shares and market value. Other indicators such as the number of employees or sales are not taken into account.

This factor strategy can also be implemented by means of an index. In this investment guide, you will find all available worldwide small-cap ETFs. Currently, there are 15 ETFs available. You may also have a look at our investment guides on Small Caps Europe and Small Caps USA.
 

When choosing a size-factor ETF one should consider several other factors in addition to the methodology of the underlying index and performance of an ETF. For better comparison, you will find a list of all size-factor ETFs with details on size, cost, age, income, domicile and replication method ranked by fund size.

Compare all size-factor ETFs in detail
Compare all size-factor ETFs in a chart

Source: justETF.com; As of 22/04/2026

Return comparison of all size-factor ETFs

The table shows the returns of all size-factor ETFs in comparison. All return figures are including dividends as of month end. Besides the return the reference date on which you conduct the comparison is important. In order to find the best ETFs, you can also perform a chart comparison.

• Cumulative
• Calendar year

Source: justETF.com; As of 31/03/2026; Calculations in GBP including dividends