Apollo Global Management's chief economist, Torsten Sløk, has warned that the current artificial intelligence (AI) stock bubble surpasses the magnitude of the dot-com bubble of the late 1990s. The top 10 companies in the S&P 500, heavily driven by AI-related stocks, are trading at approximately 28 times forward price-to-earnings (P/E) ratios, exceeding the peak multiple of around 25 times seen in 2000. These top 10 companies now represent nearly 40% of the S&P 500's market capitalization, the highest concentration ever recorded, compared to about 25% during the 1999 tech bubble. The technology sector accounts for 34% of the S&P 500, surpassing the previous peak of 33% in 2000. Market indicators underscore elevated speculation, with call options volume on the most shorted stocks spiking to levels not seen since the 2021 meme stock frenzy, and the Speculative Trading Indicator reaching one of its sharpest three-month increases, comparable only to the dot-com bubble and the 2021 meme stock surge. Additionally, the US stock market capitalization to GDP ratio has hit a record 213%, substantially higher than the 144% peak during the 2000 bubble. Analysts caution that this overvaluation and concentration in a few AI-driven tech giants could lead to a market correction potentially more severe than the dot-com crash. Despite recognition of AI's transformative potential, concerns remain about the premium investors are paying for these stocks amid signs of overhyped market enthusiasm and diminished diversification in the S&P 500.