The stock market ended May on a historic high. It also ended with a warning sign that echoes the infamous dot-com bubble of the early 21st century.
CNBC reported that only 20 companies in the index also reached their own all-time highs on that session. That narrow participation, Bank of America strategist Michael Hartnett noted, mirrors a striking detail from March 2000, when only 20 stocks hit records at the top of the dot-com bubble.
