Vanguard S&P 500 ETF(AMEX:VOO)

The fund provides comprehensive exposure to the US large-cap equity space by tracking a well-known index, the S&P 500. Like all S&P 500 funds, the fund defines large-caps as the S&P Committee sees it, which means it includes a fairly large allocation to firms that may be considered mid-caps. Stocks are market-cap-weighted, with a consideration on sector balance by comparing the weight of each GICS (Global Industry Classification Standard) sector in the underlying index to its weight in the relevant market capitalization range of the S&P Total Market Index (parent index). The index is rebalanced on a quarterly basis.