Goldman sees troubling market trend below the surface, recommends high-margin stocks

A person in a mask walks by the New York Google offices after they announced they will postpone their reopening in response to updated CDC guidelines during the outbreak of the coronavirus disease (COVID-19) in Manhattan, New York City, U.S., July 29, 2021.
Andrew Kelly | Reuters

Though the S&P 500 has roared in the last year, just five stocks are responsible for a large portion of the broad-market index's return as of late – a worrisome trend for investors, according to Goldman Sachs.