The 5K is a far more accurate indicator of the total market than the 30-stock Dow or the 505-stock S&P 500. (Yes, the S&P has more than 500 stocks because some of the companies in it have more than one class of shares.) The 5K includes 3,601 stocks, not just a relative handful of large companies the way the Dow and the S&P do.

Source: Washington Post June 28, 2021 14:26 UTC