Firms like Walmart and Apple operate in an oligopoly, where there are a small number of competing firms and a firm’s profitability depends on its interactions with other firms in the industry. Firms in an oligopoly must develop business strategies, deciding not just what price to charge and how many units to produce but also how much to advertise, which new technologies to adopt, how to manage relations with suppliers, and which new markets to enter. In 2008, Apple introduced the MacBook Air. The MacBook Air posed a challenge to other computer firms. In 2011, Samsung introduced the Series 9 notebook, and Dell introduced the XPS 15z laptop, both intended to compete with Apple’s MacBook Air. In an oligopoly market, such as the computer market, firms must continually react to each other’s actions or risk losing significant sales.