Russian oligarchs: What you need to know
21 December 2011 Last updated at 15:25 GMT
They are probably best known in the West for owning football clubs, newspapers and big, big yachts.
But who are the Russian oligarchs, how did they come to be so astonishingly wealthy and how much influence do they have in Russia now?
BBC Russian's Yevgeny Kanevsky explains the background.