When measured by total assets under management (AUM) and global financial influence, the top three investment management groups in the United States are BlackRock, The Vanguard Group, and Fidelity Investments. BlackRock stands as the largest asset manager on earth, managing multi-trillion-dollar portfolios spanning exchange-traded funds, institutional pensions, and active strategies. Vanguard pioneered low-cost index investing and mutual fund ownership, commanding trillions in passive capital. Fidelity Investments represents a massive financial services powerhouse managing comprehensive mutual funds, retirement accounts, and brokerage services for tens of millions of retail and institutional clients globally.