Urumov was giving evidence for the first time in a civil case brought by Otkritie Securities Limited, part of Russia's Otkritie Financial Corporation, which alleges that he defrauded the company by failing to split an agreed $25 million "sign-on fee" evenly between himself and four bond traders when they were recruited by the firm in 2010.
The company says that Urumov kept $20.5 million for himself and that he used more than $12 million to pay bribes to two Otkritie employees who had supported his recruitment.
Dressed in a grey suit, Urumov told the court that he had not paid any bribes and that the $12 million he paid his colleagues, Ruslan Pinaev and Sergey Kondratyuk, was because he was taking over a large portion of trading that earned the pair substantial profits.
"(Kondratyuk) was unhappy ... I was impeding his ability to earn huge profits for himself. I told them (Kondratyuk and Pinaev) I would potentially compensate them for their loss," Urumov said.
Otkritie also alleges that Urumov worked with Pinaev, Kondratyuk and another colleague, Eugene Jemai, to misprice Argentinian government securities.
The trio paid $213 million for Argentinian warrants in 2011, saying there was a binding forward trade to sell them to a third party at a higher price, according to court documents. But no forward sale was arranged and Otkritie said it later found out the warrants were worth only $53 million.
"I was not aware there was fraud," Urumov said. "I thought this was simply a commercial misunderstanding."
Barrister Steven Berry, acting for Otkritie, repeatedly dismissed Urumov's testimony as a "pack of lies" and accused him of inventing untruths on the spot.
The company earlier said none of its clients had suffered any loss in the alleged frauds and it has already recovered $52 million.
The trial continues.
(Reporting by Clare Hutchison; Editing by David Goodman)