Horizontal Growth: Acquiring vendors/companies within the same market as your own. I.e. your competitors. This decreases average cost of doing business and achieves Economies of Scale. Horizontal Growth can also mean increasing your scope of business by buying out firms that produce/sell different products. Hence, increasing your customer base.

Vertical Growth: Vertical growth, in contrast, involves a firm’s taking over a function previously performed by a supplier or a distributor. I.e. improving your supply chain relationships. Your example of buying out the advertising firm is an example of vertical growth not horizontal.

Let me know what you think…