Nvidia has reached an unprecedented milestone by accounting for over 8% of the S&P 500's market capitalization, marking the highest weighting for any single stock since records began in 1981. Its market capitalization is approximately $4.47 trillion, surpassing the previous record held by Apple at around 7% in 2023. Together with Microsoft, Nvidia now represents about 15.4% of the S&P 500's market cap, the largest combined share for any two companies in the index's history. This concentration in the US stock market is notable, with the top 10 stocks making up 40% of the S&P 500, compared to 27% at the Dot-Com Bubble peak. Despite this dominance, these companies generate only 30% of the total index earnings. The combined market capitalization of the top three US companies—Nvidia ($4.46 trillion), Microsoft ($3.93 trillion), and Apple ($3.41 trillion)—totals approximately $11.8 trillion, nearly matching the entire market cap of China, the world's second-largest stock market. Nvidia's price-to-earnings ratio stands at 58, reflecting high investor expectations amid its leadership in artificial intelligence. The S&P 500 recently hit all-time highs at 6,400 points, with financials leading broader market gains, suggesting potential rate cuts ahead. Nvidia's call option LEAPS have seen over $10 million in activity, underscoring strong market interest. This level of market concentration has not been seen since before the Great Depression or the 2000 Dot-Com Bubble, raising concerns about historic market risk.