According to @KobeissiLetter, 100% of net wealth in the US stock market since 1926 has been generated by just 3.44% of companies, meaning roughly 97% of stocks contributed minimally to long-term shareholder wealth (source: The Kobeissi Letter, X/Twitter, Oct 28, 2025). The top 1.88% of companies account for 90% of total gains, and a mere 0.26% of firms created half of all wealth, underscoring extreme return concentration in a small set of winners (source: The Kobeissi Letter, X/Twitter, Oct 28, 2025). For trading, this highlights that equity performance historically hinges on a narrow leadership cohort, making concentration risk and index composition key variables, while the post cites no direct crypto impact (source: The Kobeissi Letter, X/Twitter, Oct 28, 2025).

According to @KobeissiLetter on X, posted Sep 9, 2025, the combined weight of S&P 500 constituents with at least 3% share of the index has reached roughly 32%, tripling in eight years. Source: @KobeissiLetter on X, Sep 9, 2025. At the 2000 dot-com peak, this figure was below 10%, underscoring unprecedented concentration today. Source: @KobeissiLetter on X, Sep 9, 2025. Six companies now each exceed a 3% index weight, and NVDA alone represents about 8% of the S&P 500’s market value, both cited as records. Source: @KobeissiLetter on X, Sep 9, 2025. Higher index concentration increases sensitivity of the S&P 500 to single-stock earnings and guidance shocks, as documented by S&P Dow Jones Indices’ research on concentration risk. Source: S&P Dow Jones Indices, 2023 analysis on S&P 500 concentration risk. For crypto traders, elevated equity concentration matters because Bitcoin and U.S. equities have exhibited higher return correlations since 2020, implying spillover potential from mega-cap tech moves to BTC and ETH. Source: IMF Blog, Crypto Prices Move More in Sync With Stocks, Jan 11, 2022.

According to The Kobeissi Letter, Nvidia’s (NVDA) weight in the S&P 500 has reached a record 8.2%, more than doubling since the start of 2024, as its market value hit $4.4 trillion last week, signaling unprecedented single-name concentration at the index level, source: The Kobeissi Letter (X, Aug 16, 2025). Because the S&P 500 is float market-cap weighted, a higher NVDA weight mechanically increases passive index allocation and can amplify NVDA-driven index moves, source: S&P Dow Jones Indices, S&P 500 Index Methodology. For crypto traders, equity risk is a key input: the IMF documented a stronger return correlation between BTC and the S&P 500 during 2020–2022, indicating that large S&P swings led by mega-caps can coincide with BTC and ETH volatility, source: International Monetary Fund, 2022 analysis on crypto–equity co-movements.