Goldman Sachs traders warn the U.S. rally is narrowly driven by the “Magnificent Seven” tech stocks while most other sectors lag. Global equities, especially in Europe and Asia, have now outperformed U.S. markets for 18 consecutive months. A low ratio of advancing to declining stocks in the S&P 500 signals shallow underlying strength. Investors may need to diversify beyond U.S. large-caps as market breadth remains a weakness.