The spokeswoman said trade in Yukos shares was suspended, as it was also suspended in Russia.
The Moscow Interbank Currency Exchange (MICEX) suspended trading in Yukos shares Wednesday, after the Federal Arbitration Court upheld a lower court's decision to launch bankruptcy proceedings against the company.
But the Russian Trading System (RTS) said it would continue trading Yukos shares.
Lawyers acting for Yukos, once Russia's largest oil company, had appealed against the August 1 ruling of the Moscow Arbitration Court, which came after three years of litigation with tax authorities over the company's tax arrears.
Yukos, whose founder Mikhail Khodorkovsky is serving an eight-year prison term in Siberia after being convicted of fraud in May 2005, faces a total of $16.6 billion in claims from creditors, including its former core production unit Yuganskneftegaz ($4.07 bln), which is now owned by state-controlled oil company Rosneft; the Federal Tax Service ($11.6 bln); Rosneft itself ($482 mln); and more than 20 other companies.