Alexander Lebedev is concerned.

“Russian businessmen are very scared,” the 54-year-old former billionaire, who served in the Soviet embassy in London during the Cold War and owns Russia’s National Reserve Corp., said by phone. “There are risks to the Russian economy. There could be margin calls, reserves might be drawn down, exchange rates may fall and prices will rise. This worries me.”

Billionaires in Russia and Ukraine risk further losses as market volatility and the threat of Iran-style economic sanctions intensify following Russia’s incursion into Crimea. Since Feb. 28, the day unidentified soldiers took control of Simferopol Airport in southern Ukraine, Russia’s 19 richest people have lost $18.3 billion, according to the Bloomberg Billionaires Index, a daily ranking of the world’s 300 richest wealthiest people.

“The instability caused by the situation in Crimea could be a problem for the oligarchs,” Yulia Bushueva, who helps manage $500 million at Arbat Capital in Moscow, said in a telephone interview. “If a billionaire pledged their stakes in publicly traded companies as collateral for a line of credit, they could face margin calls and have to re-negotiate with banks.”

The U.S. and the European Union are threatening sanctions against Russia if it doesn’t back down from annexing the Black Sea province, which is holding a referendum in two days to join Ukraine’s former Soviet-era master.

‘Negative Consequences’

“All sides now understand each other’s positioning and understand the constraints each other face,” Michael O’Sullivan, chief investment officer of Credit Suisse Private Banking, said in a telephone interview. “It’s now clear as well that an escalation would have negative consequences on pretty much all the players.”

The European Union last week froze the assets of 18 Ukrainians, including “hundreds of millions of euros” in the Netherlands controlled by former President Viktor Yanukovych and his son, Oleksandr, Dutch Finance Minister Jeroen Dijsselbloem said March 6 on the television show Pauw & Witteman.

Dmitry Firtash, a 48-year-old Ukrainian billionaire who made his fortune importing Russian natural gas, was arrested in Vienna Wednesday by an organized-crime unit of the Austrian police on a warrant issued by the U.S. Federal Bureau of Investigation, according to a statement by the country’s Interior Ministry.

Outside Russia