• Claymore/Sabrient Stealth (NYSEArca: STH): up 16.9% year-to-date

IWC is the largest fund, with roughly $290 million in assets under management. Its underlying index holds 2,000 stocks, but the fund itself is optimized and includes 1,317 stocks. (Why micro- caps perform in a recovery).

PZI is a distant second to IWC in terms of assets, with just $47.8 million. PZI’s underlying index is designed to target companies that Zacks believes are likely to outperform the broad micro-cap category.

FDM has roughly $16.8 million in assets and charges an expense ratio of 0.60%. Components are selected based on liquidity and fundamentals from the designated size range, as defined by the two smallest size stocks listed on the New York Stock Exchange.

STH is the smallest ETF in the category and gives a different twist on the space. Specifically, it includes “neglected stocks” and ADRs.

For more stories about micro-cap ETFs, visit our micro-cap ETF category.