If You Learn One Indicator, Make It This One

One of the quiet, but growing, problems in the stock market is the outsized influence held by a handful of companies. Just six firms, the FAANGs and Microsoft, make up between 20 percent and 25 percent of the entire S&P 500 (depending on specific prices on any given day).

This creates… well, a lot of problems. Not only does it tie pretty much every investor in the United States to the decisions of a handful of CEOs or boards of directors, but it also undermines the pricing mechanisms that are supposed to govern the stock market. How can investors and economists get a good sense of the U.S. economy at large when the entire S&P 500 can lose value because one company had a weak product launch?

Source: https://www.thestreet.com/investing/if-you-learn-one-indicator-make-it-this-one?puc=yahoo&cm_ven=YAHOO&yptr=yahoo