More than $1 billion each from the fortunes of four Russian oligarchs, all listed by Russian Forbes and largely oil behemoths, was erased in a single day over the fall in the market.

The capital of two billionaires – Leonid Mikhelson and Gennady Timchenko – decreased by $1.5 billion, Daily Sabah reports. 

Vladimir Potanin's fortune decreased by $1.4 billion and Vagit Alekperov's by $1.1 billion.

Meanwhile, Alexei Mordashov, Russia's richest businessperson, as well as billionaires Oleg Tinkov, Viktor Rashnikov, Suleiman Kerimov and Vladimir Lisin, also lost more than $500 million in one day.

The total fortune of the top 10 Russian Forbes list has decreased by almost $7 billion, Russian Forbes said on Tuesday.

The loss of the billionaires comes against the backdrop of the collapse of the Russian stock market.

Mikhelson and Timchenko are the main shareholders of Novatek, Russia’s second-largest gas producer, whose shares fell 3.9% on Jan. 18. The shares of Norilsk Nickel, headed by Potanin, lost 5% in price all at once. The value of shares of Lukoil, which Alekperov manages, also fell by 3.65% over the same day.

On Jan. 18, the Moscow Exchange Index fell by 6.5% and the RTS index by 7.29%.

The price of Brent oil rose above $88 per barrel on Tuesday for the first time since 2014.

International benchmark Brent crude was trading at $88.22 per barrel (159 liters) at 6:36 a.m. GMT Wednesday for a 0.81% increase after closing the previous session at $87.51 a barrel.