OpenAI chief executive officer Sam Altman has warned that the artificial-intelligence sector is showing classic signs of a speculative bubble, likening the current wave of spending and valuations 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 last week, adding that “someone is going to lose a phenomenal amount of money.” Altman’s caution comes even as he projects massive outlays for computing infrastructure, saying OpenAI alone could spend “trillions of dollars” on data-centre construction. He also argued that the United States may be underestimating China’s capabilities in next-generation AI, and reiterated that OpenAI remains unprofitable despite being on course for about $20 billion in annual recurring revenue. Against that backdrop, current and former OpenAI employees are in talks to sell roughly $6 billion of stock to investors including SoftBank, Thrive Capital and Dragoneer, according to people familiar with the matter. The transaction would value the Microsoft-backed company at around $500 billion—up from a $300 billion valuation in March and nearly half a trillion dollars higher than its reported 2025 revenue base. Market observers are split on whether AI enthusiasm has outrun fundamentals. Futurum Group analyst Ray Wang argues long-term demand for chips and software supports additional investment, while Apollo Global Management economist Torsten Slok and Alibaba co-founder Joe Tsai have joined Altman in warning that current prices could eclipse those seen before the 2000 tech crash. Meanwhile, the data-centre boom that underpins the industry is already stressing U.S. power grids and water supplies, adding urgency—and risk—to AI’s breakneck expansion.