(Bloomberg) -- Russian stocks trading in New York sank for a fourth day as concern mounted that President Vladimir Putin faces stiffer international sanctions after his special forces were spotted in eastern Ukraine.

The Bloomberg index of Russian shares listed in the U.S. retreated 2.55% to a one-month low of 78.98 as 13 out of 14 stocks fell. OAO Mobile TeleSystems, Russia’s biggest mobile phone company, plunged 5.3% to the lowest level since January 2012. The escalation of the conflict halted a record inflow of money into the Market Vectors Russia exchange-traded fund, which lost 2.7% yesterday.

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