An individual registered to sell securities. A market order that specifies the highest or lowest price at which the customer is willing to trade securities. A limit order that does not expire at the end of the trading day. A market order that allows the broker to decide when to trade a security. The costs of trading securities, including the broker's taxes and commission.
Commission varies with the size of the trade.
Generally, it costs less to trade in round lots. Measures of security markets calculated from the prices of a selection of securities.