The court ruled Bakhmina guilty of embezzlement and tax evasion for stripping assets from Tomskneft, a major Yukos subsidiary.
Svetlana Bakhmina, who was arrested in December 2004, denies any wrongdoing.
Prosecutors are demanding a nine-year prison sentence.
Yukos founder Mikhail Khodorkovsky and his associate Platon Lebedev are currently serving eight-year prison sentences for fraud and tax evasion.
Critics say the trials against Yukos officials and tax claims worth billions of dollars against the oil company are part of a campaign by the Kremlin to punish Khodorkovsky for his political ambitions and tighten the state's control over the oil industry.
(Interfax, ITAR-TASS, AP)
