The stock market just did something eerily similar to the dotcom bubble top in 2000

The S&P 500 closed at a record late in May, but the rally was narrowly concentrated in a handful of names—just 20 index members hit new highs on Friday, and only seven of those weren’t AI-related. Bank of America strategist Michael Hartnett flagged the pattern as eerily similar to the dotcom top in 2000 and advised clients to adopt a defensive, post‑bubble roadmap as central bank tightening could end the narrow rally. The May advance was driven by semiconductors and memory-chip stocks (Micron, AMD, SK Hynix, Samsung), with Micron up ~85% and AMD ~50% on the month; the Nasdaq rose about 25% in April–May. Breadth measures (advance-decline lines, percent above 200‑day) lag, raising vulnerability if the market doesn’t broaden. The piece frames the market as increasingly top-heavy and at elevated risk from rising rates and weak internals.