According to @KobeissiLetter, the top 10% largest US stocks now account for a record 78% of total US equity market capitalization. According to @KobeissiLetter, this exceeds the previous record from the 1930s by 3 percentage points and is above the 74% peak seen during the 2000 Dot-Com Bubble. According to @KobeissiLetter, in the 1980s the top 10% share was below 50%, underscoring how unprecedented today’s concentration is. According to @KobeissiLetter, the top 10 stocks now represent a record 41% of the S&P 500’s market cap, indicating that market leadership is extremely concentrated.

According to @KobeissiLetter, Apple (AAPL), Microsoft (MSFT), and Nvidia (NVDA) now account for a record 17.5% of the entire US stock market, a share that has doubled over the last five years (source: @KobeissiLetter on X, Sep 8, 2025). According to @KobeissiLetter, their combined weight was just 3.1% in 2010 and 4.2% in 2015, highlighting how top-heavy the market has become (source: @KobeissiLetter on X, Sep 8, 2025). According to @KobeissiLetter, the three companies are worth $11.8 trillion in aggregate and are the only firms ever to surpass $3 trillion in market cap, with Nvidia above $4.4 trillion (source: @KobeissiLetter on X, Sep 8, 2025). According to @KobeissiLetter, tech giants are dominating the market, underscored by this record concentration (source: @KobeissiLetter on X, Sep 8, 2025).