Vanguard Mid-Cap ETF(AMEX:VO)

The fund offers market-like coverage of US midcaps. Fully replicating its index, the fund gives a good sampling of the space without major sector biases, low concentration and low turnover. Companies are selected by using shares outstanding (both total and free-float) and capitalization-based breakpoints to determine those that are considered mid-cap from the broader CRSP US Total Market Index. The resulting portfolio is a representative take on the mid-cap space. The underlying index encompasses equity securities including common stocks and real estate investment trusts (REITs) that are listed on a CRSP exchange of interest. Holdings are market cap-weighted, subject to a quarterly review.