A small group of publicly traded companies generated nearly all stock market wealth over the past 100 years, while more than 96 percent of stocks failed to outperform one-month US Treasury bills over the long term, according to a study by Arizona State University finance professor Hendrik Bessembinder, as reported by The New York Times.

The study found that technology companies dominated long-term wealth creation, led by Apple, Nvidia and Microsoft. Tesla now ranks among the top 10 wealth creators over the last century, while SpaceX briefly entered the all-time top 30 following its public debut before falling out after its share price declined, the report said. The findings highlight how a handful of companies have driven a disproportionate share of investor returns. The New York Times noted that the top 10 companies now account for 29 percent of total stock market wealth created since 1926.

The concentration of gains underscores the difficulty of picking long-term winning stocks and reinforces the case for diversified investing, according to The New York Times. While investors who correctly identified the biggest winners earned extraordinary returns, the study suggests broad market index funds remain a less risky approach for most investors as technology stocks continue to dominate global markets.