May 17, 2026, 3:11 PM

'This is borderline mania': Wall Street sees bubble-like euphoria in AI-fueled semiconductor rally

Concerns are mounting on Wall Street that the current rally in artificial intelligence-related semiconductor stocks is exhibiting signs of euphoria, with some comparing it to the dot-com bubble of the late 1990s. This sentiment suggests a potential peak is nearing for the AI-driven market surge.

The intensity of the AI rally has led some market participants to describe the environment as "borderline mania" and "casino-like." Investor Michael Burry, known for his prescient bet against the housing market, has warned that the current AI euphoria mirrors the late stages of the 1999-2000 dot-com bubble. Burry has advised investors to reduce risk rather than shorting stocks.

The concentration of market gains in a few large technology companies is a significant factor fueling these concerns. According to UBS data, five major tech stocks—Nvidia, Alphabet, Amazon, Broadcom, and Apple—accounted for approximately half of the S&P 500's gains between April 1 and May 6. This concentration is further highlighted by the fact that 10 companies now represent 40% of the S&P 500's weight, with only Berkshire Hathaway not being considered an "AI all-star" in this context.

Semiconductor stocks, in particular, have reached a record 15% of the S&P 500's total weight, according to Morningstar data. This significant weighting underscores the sector's dominant influence on the broader market index. The market's "effective number" of leadership stocks has collapsed to 42 in May, a sharp decline from the long-term average of around 100, indicating a substantial concentration of investment in a limited number of tech companies.

The debate on Wall Street is whether the current AI surge represents a genuine technological revolution or a speculative bubble reminiscent of the dot-com era. While some see the potential for sustained growth driven by AI advancements, others are cautioning investors about the risks associated with such rapid and concentrated market movements.

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