Collectively, about 6,000 companies are listed on the New York Stock Exchange and the Nasdaq Exchange, according to the Securities Industry and Financial Markets Association (SIFMA). Many of those companies are grouped into major indexes that measure various aspects the domestic market.

Wall Street is retreating from its record as a slide for Walmart weighs on U.S. stock indexes Thursday. The S&P 500 was down 0.6% in morning trading after setting all-time highs in each of the last two days.

Wall Street edged back from an all-time high following mixed profit reports from big companies. The S&P 500 barely budged on Friday and slipped by a hair, a day after rallying within 0.1% of its record set last month.