Marketing Economies:

 These are derived from the bulk purchasing of inputs and bulk distribution of outputs.  A large firm is able to buy its raw materials in larger quantities. Such bulk purchases enable the firm to obtain discounts and free transportation. It also costs a little more to sell smaller quantities of output as sales cost per unit of output sold tends to fall as the volume of sales increases.  Distribution may even be taken over  by subsidiary firms.  As sales increases, advertising cost per unit sold reduces too.  These advantages lead to a fall in per unit cost of production for the large firm.