Comcast Corporation, formerly known as Comcast Holdings, is an American multinational mass media, telecommunications, and entertainment conglomerate. Comcast's corporate headquarters is at the Comcast Center in Philadelphia, while NBCUniversal, Comcast's New York operations and other major Comcast assets are headquartered at 30 Rockefeller Plaza in Midtown Manhattan in New York City. The company was ranked 51st in the Forbes Global 2000 in 2023. It is the fourth-largest telecommunications company by worldwide revenue, after AT&T, Verizon, and China Mobile. Comcast is the third-largest pay-TV company, the second-largest cable TV company by subscribers, and the largest home Internet service provider in the United States. It owns and operates the Xfinity residential cable communications business segment and division; Comcast Business, a commercial services provider; and Xfinity Mobile, an MVNO of Verizon. The company is also the nation's third-largest home telephone service provider, serving residential and commercial customers in 40 states and the District of Columbia. Comcast has owned NBCUniversal and its various mass media subsidiaries since 2013.