On the last trading day of May, the S&P 500 closed at a record high, but only 20 of its members reached new all-time highs, a pattern reminiscent of the dotcom bubble peak in March 2000 when just 20 stocks also hit new highs at the market top [1]. According to Bank of America strategist Michael Hartnett, this narrow leadership, with most of the record-setting stocks concentrated in the AI sector, signals speculative price action that may indicate a market top is near [1]. Of the 20 S&P 500 stocks hitting records, only seven were not directly related to AI [1].
The May rally was driven primarily by semiconductor companies, with Micron Technology, Advanced Micro Devices (AMD), SK Hynix, and Samsung all valued at or near a trillion dollars [1]. AMD surged 50% in May, Micron jumped 85%, Samsung rose 43%, and SK Hynix climbed 81% [1]. The Nasdaq Composite, heavily weighted toward technology, soared 25% over April and May, marking its best two-month performance in more than two decades [1].
Despite these headline gains, market breadth has been weak. Advance-decline lines, which measure the number of rising versus falling stocks, surged at the end of March but have since retreated, a bearish signal since mid-April according to Oppenheimer's Ari Wald [1]. As of May 20, only about 55% of S&P 500 constituents were trading above their 200-day moving average, highlighting the narrowness of the rally [1]. BCA Research strategists, led by Arthur Budaghyan, noted that poor breadth is often a sign of underlying market vulnerability, even as U.S. and emerging market equity indexes reach new highs [1].
Looking ahead, Hartnett is advising clients to shift to a defensive posture, recommending long positions in bonds and defensive sectors that underperformed during the recent rally, following a 'post-bubble investor roadmap' observed since 1929 [1].
CONCLUSION
The S&P 500's record close, driven by a handful of AI and semiconductor stocks, is raising concerns among strategists about market vulnerability due to narrow breadth. Analysts are urging caution, with recommendations to adopt a more defensive investment stance as signs of a potential market top emerge.