Factors such as increased fuel costs and other high operating expenses, a decrease in business travelers due to budget cuts, and increased regulation have placed strains on airline companies. Many airlines have subsequently been forced out of business or acquired by competitors. This is illustrated by the fact that the large group of airlines that made up the industry 30 years ago has narrowed to six major firms that control a majority of the market (see Exhibit 1). These six carriers constitute five traditional airline companies (American, Continental, Delta, United, and US Airways) and Southwest, the low-cost leader.