The former JPMorgan trader known as the "London Whale" will not be prosecuted for the whopping losses he was involved in, as he made a nonprosecution deal with the Department of Justice in exchange for his cooperation, sources told CNBC.

Staff of the Commodity Futures Trading Commission and the Securities and Exchange Commission also will recommend no civil prosecution of Bruno Iksil, in light of his assistance to government investigators.

(Read more: London Whale boss's prestigious pad appears empty)

Arrests of other people involved in the $6.2 billion trading loss are seen as likely in the coming days.

In March, a U.S. Senate committee found that JPMorgan ignored risks, misled investors, fought with regulators and tried to work around rules as it dealt with growing losses in the portfolio for which Iksil was trading.

(Read More: Prosecutors And F.B.I. Examine JPMorgan)

Emails from Iksil to superiors that were later made public in conjunction with the Senate report show he tried to exit the positions he had taken once he realized he was being squeezed by traders taking the opposing positions in the small, illiquid market.