NBCUniversal (colloquially referred to as NBCU or NBCUni and formerly written as NBC Universal) is an American multinational media conglomerate. Headquartered in Rockefeller Plazas Comcast Building (formerly the GE Building) in Midtown Manhattan, New York City, the company is one of two successor companies to MCA Inc. (Music Corporation of America), the other being Vivendi through its subsidiary Universal Music Group. NBCUniversal is primarily involved in the media and entertainment industries; among its most significant divisions are NBC, one of the United States' "Big Three" television networks, and the major film studio Universal Studios. It has a significant presence in broadcasting through a portfolio of domestic and international properties, including terrestrial and pay television outlets. Via the Universal Parks & Resorts division, the company is also the third-largest operator of amusement parks in the world. NBC Universal was formed on May 12, 2004 by the merger of General Electrics National Broadcasting Company with Vivendis Vivendi Universal Entertainment. GE and US cable TV operator Comcast announced a buyout agreement for the company on December 3, 2009. Following regulatory approvals, the transaction completed on January 28, 2011. Comcast subsequently owned 51% of NBCUniversal while GE owned 49%. Comcast intended to buy out the rest of GEs stake over the following seven years, but nothing happened until February 12, 2013, when Comcast announced its intention to complete the purchase all at once and assume 100% ownership of the company by the end of March. The deal was finalized on March 19, 2013.