T-Mobile Us, Inc. (NASDAQ:TMUS)

Deutsche Telekom merged its T-Mobile USA unit with prepaid specialist MetroPCS in 2013, creating T-Mobile US. Following the merger, the firm provided nationwide service in major markets but spottier coverage elsewhere. T-Mobile spent aggressively on low-frequency spectrum, well suited to broad coverage, and has substantially expanded its geographic footprint. This expansion, coupled with aggressive marketing and innovative offerings, produced rapid customer growth. With the Sprint acquisition, the firm's scale now roughly matches its larger rivals: T-Mobile now serves 68 million postpaid and 21 million prepaid phone customers, equal to nearly 30% of the U.S. retail wireless market. In addition, the firm provides wholesale service to resellers.