Michael Calvey, a U.S. citizen and founder of the prominent Baring Vostok Equity Funds Group, was detained in Moscow along with five others late Thursday night on fraud allegations. The equity fund group, which Calvey founded in 1994, claims $3.7 billion in capital on its website. The U.S. banker has a long investment track record in the Russian technology sector and is a major shareholder in the web search giant Yandex, the Associated Press reports. Moscow’s Basmanny court said Calvey and two Baring Vostok managers are under investigation for fraud relating to Russian bank Vostochny Bank, in which Baring Vostok is a major shareholder. Russia’s Interfax news agency reported the court will rule Friday whether to keep Calvey, a director of the Atlantic Council, and his associates in custody. The others arrested were reportedly the group’s investment manager Ivan Zyuzin, partners Philippe Delpal, Vahan Abgaryan, and Alexey Kordichev, and Maxim Vladimirov, chairman of Russia’s PJSC Norvik Bank.