The agency will soon disclose the existence of the investigation, the source said on Friday.

Earlier on Friday, the New York Times reported that the CFTC had opened an enforcement case, quoting people briefed on the matter.

The CFTC would join the FBI and the U.S. Securities and Exchange Commission among federal agencies examining the loss, which the largest U.S. bank said last week was at least $2 billion.

The CFTC has disclosed an investigation into last October's collapse of MF Global Holdings Ltd, a futures and commodities brokerage from where large sums of customer money remain missing.

JPMorgan spokesman Joe Evangelisti declined to comment. The CFTC did not immediately respond to a request for comment.

The bank has not been accused of wrongdoing, and the newspaper said all of the investigations into its trading loss are preliminary.

CFTC Chairman Gary Gensler is expected to reveal his agency's investigation when he testifies before the Senate Banking Committee on Tuesday, the newspaper said.

JPMorgan Chief Executive Jamie Dimon is also expected to testify before that committee, after hearings on Wall Street reforms that are expected to end on June 6.

The CFTC began tracking JPMorgan's trading in April, the newspaper said, when reports surfaced that London-based trader Bruno Iksil was taking big bets in credit derivatives.

Its probe may examine whether the bank's trading affected that market, the newspaper said.

(Reporting By Jonathan Stempel in New York and Alexandra Alper in Washington,; Editing by Daniel Magnowski)

• A Permanent Economic Emergency