The S&P 500's top 10 stocks have seen their price-to-earnings (P/E) ratio surge to 30x, marking a significant increase compared to the broader S&P 500, which stands at 19x. This elevated valuation is reminiscent of the 1999-2000 Dot-Com Bubble and the pandemic period of 2020-2021, both of which preceded market corrections. Notably, Nvidia's stock is currently priced at $135, reflecting a P/E of 61x and a forward P/E of 30.9x. Meanwhile, investor sentiment is notably bearish, reaching its highest level in a year according to the AAII sentiment survey. In the context of Berkshire Hathaway, its stock recently hit a new 52-week high of $491.67, closing at $483.08, which represents a 34% gain over the past year. Warren Buffett's cash reserves have also reached a record $325.2 billion, constituting 28% of total assets, surpassing levels seen before the 2008 financial crisis. Despite this, Buffett has been selling stocks, including significant holdings in Apple and Bank of America, totaling $133 billion. This comes amid record bullish sentiment among investors, with 56.4% of Americans believing stock prices will rise over the next 12 months, according to the Conference Board Consumer Survey.