Academic research confirms BlackRock and/or Vanguard are among the top-3 institutional investors in all 505 S&P 500 companies (100%), and the single largest investor in 422 of them (84%). Together, the 'Big Three' control over $11 trillion in assets — more than all sovereign wealth funds combined — and own approximately 25% of voting shares in corporate America. Economists warn this unprecedented concentration could undermine competition across entire industries.