The US stock market has reached unprecedented levels, with its share of the global equity market hitting a record 56%, surpassing the peak seen during the 2000 Dot-Com Bubble. Despite this growth, US earnings account for approximately 44%, indicating a disparity between market capitalization and earnings performance. A concerning trend has emerged, where the market capitalization share of the 493 smallest S&P 500 stocks has fallen to 67%, the lowest on record, while the largest seven stocks now account for 33% of the S&P 500 index. Furthermore, the top 10% of largest US stocks represent a record 75% of the stock market, exceeding the share observed prior to the Great Depression and surpassing the 73% seen at the 2000 Dot-Com Bubble peak. Analysts warn that excessive valuations and investor overcrowding in megacap tech stocks pose significant risks to the overall US stock market and economy, compounded by competition from VC-funded startups and innovations in open-source AI.