OpenAI Chief Executive Officer Sam Altman said he believes the artificial-intelligence industry is entering a speculative bubble, likening current investor enthusiasm to the late-1990s dot-com boom. “Are we in a phase where investors as a whole are over-excited about AI? My opinion is yes,” he told reporters, adding that “smart people get over-excited about a kernel of truth” and that some investors could be left “very burnt.” Altman’s remarks, delivered late last week, helped trigger a selloff in U.S. technology shares on 19 August. The Nasdaq Composite slid 1.4 percent—its sharpest one-day decline since 1 August—while the S&P 500 fell 0.7 percent. Market leaders tied most closely to the AI boom bore the brunt: Nvidia dropped 3.5 percent, Palantir 9.4 percent, Arm 5 percent, Oracle 5.9 percent and Advanced Micro Devices 5.4 percent as investors rotated into defensive sectors. The retreat followed publication of a Massachusetts Institute of Technology study claiming that 95 percent of companies experimenting with generative AI are seeing no measurable return. European and Asian bourses echoed Wall Street’s caution: the Stoxx Europe 600 slipped 0.6 percent in early trading on 20 August and Japan’s Nikkei 225 lost 1.5 percent, with smaller declines in Hong Kong and Seoul. Wall Street strategists remain divided. Wedbush Securities’ Dan Ives acknowledged “some froth” in portions of the market but argued that the medium- and long-term economic impact of AI “is being underestimated.” Altman himself said the technology will ultimately create “tremendous” value, even while warning of near-term excesses. OpenAI is meanwhile in talks to sell about US$6 billion of employee shares in a deal that could lift its valuation to roughly US$500 billion, underscoring the scale of capital still chasing the sector.