The largest segment of the asset management business in the United States is registered investment companies (regulated funds). This article focuses on U.S. regulated investment companies - mutual funds, exchange-traded funds, closed-end funds, and unit investment trusts. These funds manage more than 17 trillion of assets, largely on behalf of U.S. investors. The industry has experienced strong growth over the past quarter century from asset appreciation and strong demand from households due to rising household wealth, the aging of the U.S. population, and the evolution of employer-based retirement systems. Price competition and supply-side product innovations and efficiencies have reduced the average price that investors pay for fund services. © 2104 National Association for Business Economics.