It's useful to the classical music CD and DVD collector to have a general idea of the music market. The major music producers and distributors along with their main classical music labels are listed below. Three major companies dominate the market with different labels although there are some important smaller distributors.

Sony Classical (Sony Music)
Columbia/CBS
Deutsche Harmonia Mundi
Eurodisc
ECM
RCA Victor
Sony BMG

Universal (UMG)
Archiv
Argo
Decca/London
Deutsche Gramophone
Hyperion
L'Oiseau-Lyre
Mercury
Philips

Warner Classics (WMG) 
Warner
Elektra-Nonesuch
Erato
Finlandia
Lontano
Teldec
NVC Arts (video)
(EMI Classics)
EMI (now issued as Warner)
Angel Studio
Pathe Marconi
Reflexe
Virgin

Other major distributors
Allegro
Brilliant Classics
BIS
Chandos
CPO (Recordings List)
EuroArts (video)
Gimell
Harmonia Mundi
Hungaroton
Koch International
Naxos