Measured by invested assets, the S&P 500 index is the most common index fund benchmark in the U.S. The S&P 500 tracks about 75% of publicly traded U.S. equity market asset value. You might think that you can pick any old S&P500 benchmarked index fund or ETF and thereby adopt a passive, low cost, broad market index strategy. Nope. Life just never seems to be that easy. This article lists S&P 500 mutual funds that a recent study found were the best mutual funds from the standpoint of lower investment costs.
The dominant issue with S & P 500 index mutual funds and ETF funds is that securities industry fees are all over the map from reasonably low to shockingly high. If you are naive enough to pay higher investment costs for commodity index funds, then these ridiculously high fees are just a wealth transfer from you to the industry that repeatedly bleeds your personal investment portfolio year after year.