The Claymore Wilshire 4500 Completion Index, which is designed to follow the performance of the Wilshire 4500, tracks all companies trading in the United States that are not included in the S&P 500. The WREI is designed to be a pure play for investors seeking a play on all available REITs trading in the U.S. While WXSP and WREI are the first of their kind, this is not the first time an ETF or mutual fund has attempted to copy the performance of the all-encompassing Wilshire 5000. The SPDR Dow Jones Total Market ETF ( TMW) tracks the same index as WFVK, although its basket is made up of considerably fewer positions. Additionally, while they track the MSCI US Broad Market Index today, the Vanguard Total Market ETF ( VTI) and Vanguard Total Stock Market Index Fund ( VTSMX) originally tracked the Wilshire 5000. Aiding the appeal of Claymore's new instrument is an attractive 0.12% expense ratio. By comparison, TWM, which will suffer from greater tracking error due to its more concentrated exposure, charges 0.21%. WXSP will cost investors 0.18% while WREI charges 0.32%. Although WFVK is a great fund for investors looking for the ultimate equity catch-all, in the end, the largest hurdle standing in this fund's way will be volume. Despite the fact that investors are returning to broad equity index funds, the Wilshire 5000 has not traditionally been as appealing to investors as the S&P and Dow. As a result, TWM has typically been an illiquid fund. Claymore's new instrument will have to rely on its more diverse holdings and cheap expense ratio to pull in investors. If it fails on those scores, this fund will most likely falter. -- Written by Don Dion in Williamstown, Mass.