The US stock market is currently exhibiting valuations and concentration levels that surpass those seen during the 2000 Dot-Com Bubble and even the pre-Great Depression era. The S&P 500's forward price-to-earnings (P/E) ratio has reached 22 times, the highest in five years, while the Information Technology sector within the MSCI World index has a 12-month forward P/E ratio of 27 times, placing it in the top 10% of the most expensive readings over the past 20 years. Growth stocks trade at approximately 26 times forward P/E, also near historic highs. Technology stocks relative to the S&P 500 hit a record ratio of 2.2 times in July 2025, exceeding levels observed at the Dot-Com Bubble peak and standing more than two standard deviations above the historical average. The S&P 500 Information Technology sector's price relative to the overall S&P 500 has doubled over the last eight years to 0.83 points, an all-time high. Additionally, the market capitalization weight of the top 10% largest US stocks has reached approximately 76%, surpassing previous records set before the Great Depression and exceeding the 73% share at the 2000 Dot-Com Bubble peak. Various valuation metrics, including trailing P/E, forward P/E, Shiller P/E (CAPE), price-to-book, price-to-sales, EV/EBITDA, Q ratio, and market cap to GDP ratio, have all hit historic highs. While technology stocks are outperforming the S&P 500 by the largest margin since the Dot-Com Bubble, healthcare stocks are underperforming by the widest margin in nearly 25 years. The US accounts for 65% of the MSCI World Index, and these elevated valuations underscore heightened risk levels in the market.