In the context of online retail stockbrokerages and financial services within the United States, the "Big 3" discount brokerages that traditionally dominated retail trading volumes are Charles Schwab, Fidelity Investments, and Vanguard. These massive financial institutions manage trillions of dollars in customer assets, offering low-cost or commission-free equity trading, comprehensive retirement account administration, extensive mutual fund and exchange-traded fund selections, and advanced investment research tools for millions of individual investors.