Exchange-traded funds, more commonly called ETFs, are index funds traded just like stocks. Great U.S. companies or small ones, international stocks, real estate thrusts, etc. are into the ETS trading system. However, only a few are the cream of the crop, the so-called biggest and brightest. Currently the 1st and the biggest ETF is still Standard & Poor’s 500 Index Depository Receipts. It tracks the S & P 500 index. Following suit are the following: Nasdaq-100 Index Tracking Stock, Diamonds Trust, iShares S & P 500, Standard & Poor’s MidCap 400 SPDRs, iShares Russell 2000 and a few more. These are the most trusted names when talking about ETFs.