The fee paid to a broker to execute a trade, based on number of shares, bonds, options, and/or their dollar value. In 1975, deregulation led to the establishment of discount brokers, who charge lower commissions than full service brokers. Full service brokers offer advice and usually have a staff of analysts who follow specific industries. Discount brokers simply execute a client's order and usually do not offer an opinion on a stock. Also known as a round-turn.