(Bloomberg) -- Russia’s super-rich tycoons lost more than $3 billion in one day after a top economic aide to the president proposed raising taxes on the nation’s giant metal and mining companies.

In a letter to Vladimir Putin, adviser Andrey Belousov named 14 companies that could pay more. The resulting investor exodus saw $3.1 billion wiped off the fortunes of their affluent bosses, according to the Bloomberg Billionaires Index.

The companies that would be affected by the plan include MMC Norilsk Nickel PJSC, co-owned by tycoon Vladimir Potanin; Severstal PJSC, where magnate Alexey Mordashov is the largest shareholder; and petrochemical group Sibur Holding PJSC, controlled by Leonid Mikhelson and Gennady Timchenko.

The proposal could raise as much as 500 billion rubles ($7.4 billion) a year to help fund Putin’s spending plans, according to Belousov’s letter, obtained by Bloomberg News. It would also affect chemical and fertilizer producers.

The proposition “looks like a promotion of inefficiency,” Vladimir Lisin, the controlling shareholder of Novolipetsk Steel PJSC and head of the Russian Steel Association, said in emailed comments. “The lower the profitability, the less taxes you will have to pay.”

Lisin lost the most among the affected billionaires as Novolipetsk Steel slumped 5.4 percent in Moscow trading on Friday. His $832 million loss equates to about 4 percent of his net worth, according to the billionaires index. Viktor Rashnikov, owner of Magnitogorsk Iron & Steel Works PJSC, was the second-biggest loser as his company dropped 5.2 percent.

The Bloomberg Billionaires Index tracks the wealth of the world’s top 500 richest people.

--With assistance from Jack Witzig.

To contact the reporter on this story: Alex Sazonov in Moscow at asazonov@bloomberg.net

To contact the editors responsible for this story: Pierre Paulden at ppaulden@bloomberg.net, Amanda Jordan, Keith Campbell

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