Who was the successful bidder for Yukos's main production unit at the weekend?

Baikal Finance Group is a previously unknown entity, presumed by many to be a front for another bidder or bidders. Reports indicate it was recently registered at an address, said to be a grocers, in Tver, a city north of Moscow.

There is no information as to its owners or its ability to fund the $9 billion purchase of Yuganskneftegaz, or Yugansk, the Yukos subsidiary that was sold.

Who might Baikal Finance represent?

In the absence of facts, speculation is rife - as is usual in Russia.

The prime suspect is Gazprom, the state-controlled gas utility which made clear its interest in acquiring Yugansk through its newly created oil business, Gazpromneft.

However, Gazprom declined to bid at Sunday's auction and it is possible that the threat of litigation may have deterred the company, at least temporarily, from making a bold move. Last week, Yukos commenced bankruptcy proceedings in Houston while Menatep, the financial company which holds the interest of Mikhail Khodorkovsky, the jailed Yukos shareholder, has threatened to sue any acquirer of Yugansk and any bank that finances a purchaser. Gazprom has significant assets abroad, including in the UK, and will be cautious to protect its wider interests.

If Baikal Finance is not a front for Gazprom, speculation moves to Surgutneftegaz, an oil and gas producer that is considered to be friendly to the Kremlin. Surgut has a large hoard of cash and is the only company, other than Gazprom, with the financial muscle to mount such a bid.

A foreign buyer is unlikely, as it would detract from what appears to be part of the Russian government strategy - to restore state control over an important energy asset.

Finally, there is the possibility that Baikal Finance will not complete the purchase and that its role is simply to provide the government with time to consider its options, to mount a second auction or to prepare legislation for the nationalisation of Yugansk.

Is the price that Baikal paid fair?

That depends on whether you consider the tax claims against Yukos to be legitimate. They total some $27 billion and are dismissed by the company as a backdoor attempt to expropriate Yukos from its shareholders.

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