Record Labels

In the music industry, a record label is a brand and a trademark associated with the marketing of music recordings and music videos. Most commonly, a record label is the company that manages such brands and trademarks, coordinates the production, manufacture, distribution, marketing and promotion, and enforcement of copyright protection of sound recordings and music videos; conducts talent scouting and development of new artists and maintains contracts with recording artists and their managers. The term "record label" derives from the circular label in the center of a vinyl record which prominently displays the manufacturer's name, along with other information.
Major labels 1988–1998 (Big Six)

1. Warner Music Group
2. EMI
3. Sony Music
4. BMG Music
5. Universal Music Group
6. Polygram

Major labels 1998–2004 (Big Five)

1. Warner Music Group
2. EMI
3. Sony Music
4. BMG Music
5. Universal Music Group

Major labels 2004–2008 (Big Four)

1. Warner Music Group
2. EMI
3. Sony BMG
4. Universal Music Group

Major labels since 2009 (Big Four)

1. Sony Music Entertainment
2. EMI Group
3. Warner Music Group
4. Universal Music Group

Sourced; http://en.wikipedia.org/wiki/Record_label