Trading Order Types Market, Limit, Stop and If Touched For example, assume a stock is trading at $16.50. A MIT buy order could be placed at $16.40. If the price moves to $16.40 or below, the trigger price, then a market buy order will be sent out. For a sell order, assume a stock is trading $16.50. A MIT sell order could be placed at $16.60. The key difference between commodity exchange and stock exchange is that a commodity exchange is an exchange where commodities are traded whereas stock exchange is an exchange where stock brokers and investors buy and/or sell stocks, bonds, and other securities. Both types of exchanges are driven by the demand and supply for commodities or financial instruments. As a speculator simply trading to make a profit from trading itself and with no interest in actually taking delivery of product, you will simply sell your contract prior to delivery at the going market price and the difference between your buy price and sell price is either your profit or loss. When you buy a stock, you are part owner of a company.