The German bank, which has a market capitalization of around $30 billion, declined to comment to CNBC.
The $4 billion figure is in addition to the $6 billion in so-called mirror trades that the bank is investigating. These involved clients buying shares for rubles in Russia and simultaneously selling them in London, potentially allowing them to move money offshore without telling authorities, according to Bloomberg sources.
In September, the bank announced the closure of its corporate banking and securities business in Russia.
The bank has faced tough scrutiny from global regulators this year. Last month, it agreed to pay $258 million in penalties to settle charges for conducting business for groups in U.S-sanctioned countries. In April, it was fined a record $2.5 billion by the U.S. and Britain over alleged interest-rate rigging.