Ouch! Russian billionaires have lost more than $50 billion this year due to the country's unfolding economic nightmare.

Western sanctions, low oil prices and the falling ruble have wiped billions off the wealth of Russia's 15 richest men, according to data from Bloomberg.

Here are the top 10 losers:

Leonid Mikhelson

The chairman of Russian gas producer Novatek has suffered the biggest losses, seeing his portfolio shrink by an estimated $8.7 billion. That's equivalent to a loss of nearly 50%.

Novatek was one of the first companies to be sanctioned by the U.S. over the crisis in Ukraine.

Vladimir Lisin

The chairman and largest shareholder of Novolipetsk Steel, and once Russia's richest man, has lost $7 billion, also nearly 50% of his wealth.

He is the vice president of the Russian Olympic Committee and the president of the European Shooting Confederation -- and as a gun enthusiast reportedly owns a valuable collection of rifles.

Related: Russia heading for crash as ruble plummets

Alisher Usmanov

The metals magnate owns Russian daily newspaper Kommersant. In 2011, he sacked the editor after he published a picture of a ballot paper with "Putin, go f*!k yourself" scrawled on it in red ink.

Usmanov has lost $6.4 billion so far this year. He controls 48% of Metalloinvest, Russia's largest iron ore producer. He also has a share in Twitter (TWTR) and Airbnb, and co-owns English soccer team Arsenal, Bloomberg data show.

He is also the president of the International Fencing Federation.

Andrey Melnichenko

The self-made coal and minerals magnate is another Russian billionaire feeling the chilling effect of Western sanctions and falling oil prices. He has lost nearly 40% of his wealth, or about $5.8 billion.

He is married to a former Serbian supermodel and owns one of the world's most admired super yachts -- the A.

Sergey Galitsky

The founder and owner of Russia's biggest food retailer Magnit is down over $5 billion. The soccer enthusiast is famous for pouring more than $250 million into his local Krasnodar club, building an arena and a sports academy.

He is thought to have lost over $855 million on Monday alone as the ruble went into free fall.

Vagit Alekperov

The chairman of Russian oil giant Lukoil was once a Soviet energy minister.

Lukoil was the first privately-owned company to be sanctioned by the U.S. over the Ukraine crisis. His wealth has fallen by $4.9 billion, or about 40% so far this year.

Mikhail Fridman

The investment mogul has watched $3.5 billion evaporate.

He made his fortune on the sale of joint venture TNK-BP to Rosneft. Together with his partner German Khan, Fridman controls Alfa Bank, Russia's largest private lender.

Vladimir Potanin

The former deputy prime minister is currently the head of the world's biggest nickel producer Norilsk Nickel. His wealth has fallen by $2.8 billion, or about 20%.

Potanin was one of the main backers of Russia's bid to host the 2014 Sochi Winter Olympics, and he invested heavily in the development of the Olympic village.

German Khan

Mikhail Fridman's partner in Alfa Bank sold his stake in TNK-BP to Rosneft for $3.3 billion in 2013, according to Bloomberg.

He's lost $2.5 billion this year, equivalent to about 22% of his wealth.

Mikhail Prokhorov

Prokhorov's company Onexim group owns stakes in the Russian banking, energy and mining sectors. He's lost $2.4 billion.

Prokhorov also owns the Brooklyn Nets. He said earlier this year he was considering moving the company that controls the NBA team to Russia in order to comply with Vladimir Putin's call for Russian-owned companies to be based there.

He has criticized Russian policies in the past, condemning the country's anti-gay laws.