iShares S&P 100 ETF(AMEX:OEF)

OEF is a pure large-cap fund, designed to track an index of the 100 largest and most stable blue chip companies in the S&P 500. By rule, stock options are available on all underlying stocks (and on the ETF itself), which speaks to the funds deep underlying liquidity. To be included, companies must have an unadjusted market cap of USD 8.2 billion or greater, and a float market-cap of at least USD 4.1 billion. They must also have positive as-reported earnings over the most recent four quarters and a minimum trade of 250,000 shares in each of the six months leading up to the evaluation date. Ultimately, as is common in most S&P funds, a committee has full discretion as to the composition of the index, sector balance is also considered in the selection of companies. The index is float-adjusted market cap weighted and is rebalanced quarterly.