Nvidia's market capitalization has soared to approximately $5.4 trillion, now accounting for 8% of the S&P 500's total value. This remarkable growth positions Nvidia as larger than seven of the index's 11 sectors, marking the highest single-stock concentration since 1981. The company's dominance is driven by surging demand for its AI-focused chips, which have become essential for training and running large language models. Nvidia's ascent highlights a significant structural risk for passive investors, as every dollar invested in an S&P 500 index fund allocates eight cents to Nvidia. This concentration underscores the importance of understanding portfolio exposure, especially as Nvidia's GPUs remain critical to the AI infrastructure boom. Despite competition from AMD and custom silicon efforts by tech giants, Nvidia's advanced chips and software ecosystem continue to drive its market leadership.