Mid-Cap Viper

According to a report from Standard & Poor's, the year 2005 belonged to mid-cap stocks which gained 12.6% versus 4.9% for large-caps and 7.7% for small-company stocks. This year through May 10, the S&P MidCap 400 index, which measures companies with market capitalizations between $1 billion and $4 billion, rose 10.4%.

Vanguard has recently filed a registration statement with regulators for a pair of index funds and matching Vipers ETFs designed to track midcap stocks. If approved, these ETFs would cover the growth and value sections of mid-sized companies and would increase the company's total ETF count to 26 offerings. The pair would also round out Vanguard's lineup to cover all nine "style boxes" for U.S. stocks (A cross table comprising Large-, Mid-, Small- for rows and Value-, Growth-, Balanced- for columns or vice versa).