Wall Street is retreating from its record after a slide for Walmart weighed on U.S. stock indexes Thursday. The S&P 500 was down 0.7% in afternoon trading after setting all-time highs in each of the last two days.

Microsoft was the strongest force pushing the S&P 500 upward. It rose 1.3% after saying it had developed what it calls the world’s first “quantum processing unit,” which cou