American financial-services holding company whose principal subsidiary, Merrill Lynch, Pierce, Fenner & Smith Inc., is the largest retail brokerage house in the United States. Headquarters are in New York City.

In 1914 Charles E. Merrill (Merrill, Charles E.), a bond dealer, founded a small investment-banking firm and the next year took on a partner, Edmund C. Lynch. Merrill, Lynch & Company prospered by specializing in underwriting the securities of chain stores. Having helped organize Safeway Stores in 1926, Merrill sold his firm's retail brokerage operations to E.A. Pierce & Company in 1930 and concentrated on investment banking until 1940, when he merged his firm with that of Pierce to form Merrill Lynch, E.A. Pierce & Cassatt. In 1941 the company merged with the New Orleans-based brokers Fenner and Beane.

Under Merrill's leadership, the brokerage house (then called Merrill Lynch, Pierce, Fenner & Beane) set out after World War II to bring “Wall Street to Main Street,” explaining to middle-income Americans how the stock market works and bringing average investors into the market in unprecedented numbers. Through innovative public-relations techniques, widely copied by other brokers, the company extensively advertised its services, cultivated small accounts, established a training school for stockbrokers, and paid brokers a salary instead of straight commission to reduce the incidence of needless portfolio churning to generate commissions. Merrill Lynch also was the first brokerage house to publicly disclose its own securities holdings. With the addition of Winthrop H. Smith to the partnership in 1958, the firm became Merrill Lynch, Pierce, Fenner & Smith.

In the 1970s, under Chairman Donald T. Regan (later treasury secretary under President Ronald Reagan), the firm moved aggressively into such other financial services as insurance and established the country's largest money-market mutual fund. The holding company was created in 1973. Under Merrill Lynch International, it has several international operations, including Smith New Court PLC, a British securities firm acquired in 1995. In September 2008 Bank of America Corporation announced plans to acquire Merrill Lynch, pending the approval of both companies' regulators and shareholders.