Six of Russia's biggest companies have as much as $17 billion in cash that may be used to buy back shares to help mitigate the biggest quarterly market slump in a decade, VTB Group said.

LUKoil, Surgutneftegaz, TNK-BP, Norilsk Nickel, Severstal and Magnitogorsk Iron & Steel are among the 16 companies that either have said they will buy back shares or have enough cash to do so, state-run VTB said.

Russian stocks are the worst performing this quarter of the 88 national indexes tracked by Bloomberg. The dollar-denominated RTS Index has lost 45 percent since July as tightening liquidity and Russia's war with Georgia led investors to pull out money.

"Lots of Russian companies compensate their top managers with stock options," VTB strategist Ivan Ivanchenko wrote in a note to investors Monday. "A buyback is likely to drive prices higher, which in turn makes managers better off."

Wimm-Bill-Dann, the country's largest dairy producer, may decide this week to buy back 10 percent of its stock on the open market after the price fell 43 percent in three months, chairman David Yakobashvili said Monday. The shares gained 9 percent to close at $73.12 in New York on Sept. 12, valuing the company at $3.22 billion. About half of Wimm-Bill-Dann's stock is traded.

The food producer only has about $38 million to spend now, although it has relatively low investment plans and strong cash flow, VTB's Ivanchenko said.

Norilsk Nickel, the country's biggest mining company, advanced as much as 8.4 percent in Moscow on Monday amid speculation that management or its billionaire shareholders may be buying back shares. The stock was the only gainer in the 30-stock MICEX Index on Monday. VTB estimated that Norilsk, which said it may buy 4 percent of stock on a pro rata basis, has about $4 billion in cash available.

LUKoil, the country's biggest nonstate oil producer, said last week that it would ask the board to approve a buyback program, after chief executive Vagit Alekperov and his deputy Leonid Fedun bought 3.2 billion rubles ($124 million) of stock.

UralSib said Monday that it was "skeptical" of the proposal.

"We do not believe that the company would have sufficient cash assets in the fourth quarter to meet such an obligation, as revenue has been hurt by the fall in oil prices," while capital spending and costs have increased, UralSib said.

Missing from VTB's list were VTB's own shares, which JPMorgan Chase said should be bought back because the bank "appears to be struggling to deploy its capital efficiently."

"With the bank's own shares at distressed levels, the case for a buyback is compelling," JPMorgan analysts Alex Kantarovich and Oxana Segedevich wrote in a note dated Sept. 10.

VTB had $5 billion in cash and short-terms funds as of March 31, according to financial results released on Aug. 28. VTB shares have fallen 62 percent in Moscow since the company's $8 billion initial public offering, the world's biggest last year.

A senior executive at Russian steel group Evraz bought shares in the company last week, the company said in a filing Monday.

The filing said Timur Yanbukhtin, Evraz vice president for business development and strategic planning, bought 2,000 Evraz Global Depositary Receipts at $59.90 each.

Yanbukhtin now owned 36,537 GDRs directly and was the beneficiary of another 3,000, the filing said.

The company did not immediately respond to a request for comment.

The GDRs were trading at $63 in London on Monday, down 4.55 percent on the day after a market bounce on Friday.