The document provides information about 4 major music companies in the UK music industry:
1) EMI was once one of the "big four" record companies but is now owned by Citigroup and being sold off in parts.
2) Universal Music Group is the world's largest music company with a network of record labels.
3) Warner Music Group owns record labels like Atlantic and Elektra and is a major music publisher.
4) Sony Music Entertainment is the second largest global recorded music company and is controlled by Sony Corporation of America.