Discount brokers generally offer fewer services and lower trading commissions than full-service brokers like Merrill Lynch. Discounters cater to do-it-yourself investors who don’t need stock research, advice and other personalized services. The industry was born on May 1, 1975, when the Securities and Exchange Commission ordered brokerage firms to eliminate fixed commissions.

In recent years, the line between discount and full-service firms has become blurred. Discount pioneers such as Charles Schwab have moved upscale, providing more advice and services. This has opened the door for deep discounters that provide nothing but an online trading platform and rock-bottom commissions. Other large discounters include E-Trade and TD Ameritrade.