The S&P 500 and Nasdaq reached historic highs driven by AI optimism and strong financial reports, but the gains were mainly contributed by large tech stocks. UBS analysts said that in the six weeks ending May 15th, the market value weighted S&P 500 index had the largest lead in at least 35 years compared to an equally weighted index, and recommended reducing concentrated positions and preventing risks. Ipek Ozkardeskaya, an analyst at Ruixun Bank, said that the gains were concentrated in a few technology companies, and if the pricing logic went wrong, it could trigger a collapse.
